Sum Insured Explained
With construction costs unstable, make sure your rebuild cost is fully insured - our guide explains everything you need to know.
Updated 11 April 2026
Summary
To help you understand sum insured (and why it's important to get right), our guide outlines:
Know This First: Sum Insured cover is one of two ways to protect your home - you may also want to consider Area Replacement cover. Our guide to Sum Insured vs Area Replacement explains more.
How Much Should I Insure My House and Contents For?
In the video below, MoneyHub Founder Christopher Walsh outlines how sum insured calculators work, why you must ensure you have enough coverage every time you renew or switch insurers, and important must-know facts and considerations:
Summary
- Sum insured means the maximum amount your insurance provider will pay to rebuild your home or replace your belongings in case of a claim.
- Too many New Zealanders are underinsured and only find this out when they make a claim, usually for total loss, and get much less than they need or expect.
- Our guide explains how significant changes to your property can affect your sum insured and why it's important to update your policy to reflect these enhancements.
To help you understand sum insured (and why it's important to get right), our guide outlines:
- Home vs Contents Insurance Sum Insured Explained
- Calculating Home and Contents Sum Insured
- Case Studies - Adjusting the Sum Insured for Home, Home and Contents, and Contents Insurance Policies
- Frequently Asked Questions
Know This First: Sum Insured cover is one of two ways to protect your home - you may also want to consider Area Replacement cover. Our guide to Sum Insured vs Area Replacement explains more.
How Much Should I Insure My House and Contents For?
In the video below, MoneyHub Founder Christopher Walsh outlines how sum insured calculators work, why you must ensure you have enough coverage every time you renew or switch insurers, and important must-know facts and considerations:
Important: Understand the Hidden Risk Most Homeowners Don't Know They're Carrying
With sum insured, you're betting rebuild costs won't spike before you need to claim. History shows that this bet fails repeatedly when there is a natural disaster - Christchurch homeowners faced 40-70% cost spikes, leaving many with shortfalls of $200,000 or more, and the same happened after Gabrielle.
How Area Replacement Insurance Cover Eliminates This Risk:
Who Benefits Most from Area Replacement House Insurance Policies:
The MAS Difference: As a not-for-profit owned by members, MAS doesn't profit from claim denials or coverage gaps. They exist to pay claims, not protect shareholder profits. That's why they're the only insurer offering true area replacement.
Check Your Real Coverage Now: See how MAS area replacement protects you when sum insured cover is insufficient.
Important: The cheapest insurance is expensive if it leaves you $200,000 short. The best insurance - the kind that actually works - costs slightly more but delivers when disaster strikes.
With sum insured, you're betting rebuild costs won't spike before you need to claim. History shows that this bet fails repeatedly when there is a natural disaster - Christchurch homeowners faced 40-70% cost spikes, leaving many with shortfalls of $200,000 or more, and the same happened after Gabrielle.
How Area Replacement Insurance Cover Eliminates This Risk:
- No sum insured cap - Coverage based on your home's actual square meters, not a dollar guess - you can get a quote of the cost from MAS here.
- Automatic inflation protection - When building costs spike 40% after disasters, you're covered
- No annual revaluations needed - MAS, as the primary provider of area replacement, tracks rebuild costs, so you don't have to
- Proven disaster performance - MAS customers rebuilt fully after Christchurch, floods, and Gabrielle - our MAS policyholder testimonials explains more.
Who Benefits Most from Area Replacement House Insurance Policies:
- Character home owners (impossible to value accurately)
- Anyone in disaster-prone areas
- Homeowners who want genuine "set and forget" insurance
- Those who understand that paying 10-20% more eliminates 100% of shortfall risk
The MAS Difference: As a not-for-profit owned by members, MAS doesn't profit from claim denials or coverage gaps. They exist to pay claims, not protect shareholder profits. That's why they're the only insurer offering true area replacement.
Check Your Real Coverage Now: See how MAS area replacement protects you when sum insured cover is insufficient.
Important: The cheapest insurance is expensive if it leaves you $200,000 short. The best insurance - the kind that actually works - costs slightly more but delivers when disaster strikes.
Home vs Contents Insurance Sum Insured Explained
If you're insuring both home and contents, please read both the home and contents sections below. Otherwise, refer to the section that applies to your needs.
1. Understanding Home Insurance Sum Insured
The sum insured is the agreed-upon amount with your insurer that represents the cost of rebuilding your home from scratch in the event of total destruction. The sum insured amount is crucial as it determines the maximum payout you would receive if you need to rebuild your home due to incidents like fires, severe earthquakes, floods, natural disasters, or other significant damages.
The sum insured is agreed upon between you and your insurer when you first purchase your home insurance policy and at each renewal. To ensure accuracy, this amount should be reviewed and updated regularly to reflect any changes, such as renovations or extensions.
Please be aware that Rebuild Cost is not the same as Market Value. The sum insured is based on the rebuild cost, not the market value or the purchase price of your property. Market value includes the cost of the land, which insurance does not cover, whereas the sum insured should only cover the structure of the home and the costs associated with rebuilding it to the same standard.
What's included in rebuild cost?
The sum insured is agreed upon between you and your insurer when you first purchase your home insurance policy and at each renewal. To ensure accuracy, this amount should be reviewed and updated regularly to reflect any changes, such as renovations or extensions.
Please be aware that Rebuild Cost is not the same as Market Value. The sum insured is based on the rebuild cost, not the market value or the purchase price of your property. Market value includes the cost of the land, which insurance does not cover, whereas the sum insured should only cover the structure of the home and the costs associated with rebuilding it to the same standard.
What's included in rebuild cost?
- The rebuild cost must include several significant costs beyond the building materials and labour.
- Your sum insured must include demolition, debris removal, council fees, consulting, and professional fees. It must also take into account specific features of your home, such as the quality of construction, design, and any unique features.
- Reminder: Sum Insured cover is one of two ways to protect your home - you may also want to consider Area Replacement cover. Our guide to Sum Insured vs Area Replacement explains more.
2. Understanding Contents Insurance Sum Insured
The sum insured is the total value of all personal belongings you wish to cover within your home. This means that you can replace your items without suffering a financial burden in the event of theft, loss, or damage.
The sum insured for contents insurance should reflect the total value of all your personal belongings. This includes furniture, electronics, clothing, jewellery, and other valuable items. You need to be accurate in estimating the value of your contents to ensure you have sufficient coverage.
Know This: Contents insurance typically covers the replacement cost, meaning the amount it would cost to replace your items with new ones of similar kind and quality. Replacement cost is not the same as 'cash value', which is what you could sell the items for second hand, e.g. on Trade Me, given that 'cash value' includes depreciation.
Updating your contents insurance and getting your sum insured regularly is important. A new TV, laptop, phone, or e-bike can be expensive, so it's critical to ensure your sum insured is comprehensive and adequate.
Overall, having an accurate sum insured is essential to ensure you're covered for full loss while avoiding financial strain by a shortfall from underinsurance. Also, if your sum insured is too high, you could pay unnecessarily high premiums without added benefit.
The sum insured for contents insurance should reflect the total value of all your personal belongings. This includes furniture, electronics, clothing, jewellery, and other valuable items. You need to be accurate in estimating the value of your contents to ensure you have sufficient coverage.
Know This: Contents insurance typically covers the replacement cost, meaning the amount it would cost to replace your items with new ones of similar kind and quality. Replacement cost is not the same as 'cash value', which is what you could sell the items for second hand, e.g. on Trade Me, given that 'cash value' includes depreciation.
Updating your contents insurance and getting your sum insured regularly is important. A new TV, laptop, phone, or e-bike can be expensive, so it's critical to ensure your sum insured is comprehensive and adequate.
Overall, having an accurate sum insured is essential to ensure you're covered for full loss while avoiding financial strain by a shortfall from underinsurance. Also, if your sum insured is too high, you could pay unnecessarily high premiums without added benefit.
Calculating Home and Contents Sum Insured
If you're insuring both home and contents, please read both the home and contents sections below. Otherwise, refer to the section that applies to your needs.
1. Home Insurance
- Using online calculators is a convenient way to estimate your sum insured, and we stand by the accuracy of the Cordell Sum Sure Calculator, which helps you determine the rebuild cost of your home.
- Cordell's tool estimates the typical building replacement costs for standard residential homes. It considers factors such as floor area, construction materials, and quality of finishes. To get an accurate sum insured estimate, you'll need to obtain accurate data (square meterage of property, special fixtures, etc).
- Our guide to house insurance calculators has more information to help you get an accurate estimate from Cordell.
- Alternative Option: Beyond an online tool, consulting professionals can offer a detailed evaluation to get a tailored sum insured amount. Builders, architects, or quantity surveyors can assess your property's rebuild cost in-depth. These professionals will consider all the specifics of your home, including construction materials, quality of finishes, and any unique features, providing a comprehensive rebuild cost estimate.
- Professional assessments cover various elements that might be overlooked in online calculators, including demolition costs, debris removal, council fees, consulting fees, and other professional fees, ensuring that your sum insured is comprehensive and accurate.
- Related resources: Our trusted go-to guides for Insuring an Old House and Difficult Areas for House Insurance explain what you need to know should either of these issues apply to you as the sum insured amount needs further consideration.
- Reminder: Sum Insured cover is one of two ways to protect your home - you may also want to consider Area Replacement cover. Our guide to Sum Insured vs Area Replacement explains more.
In the video below, MoneyHub Founder Christopher Walsh demonstrates how to use Cordell's house insurance sum insured calculator:
2. Contents Insurance
- Estimating the sum insured for your contents can also be simplified by using online calculators to get a benchmark of the replacement value of your personal belongings.
- An independent tool provided by Australian company Sum Insured Pty Ltd uses your address to give an estimate. The calculator does not constitute financial advice and is for guidance only.
- You can visit the calculator here.
- Alternative Option: Add up the value of what you own and estimate what they would cost to replace - we make this easy using our Contents Insurance Template. Please note, when you buy contents insurance, you do not need to list everything you own, but knowing the total value is important to avoid being under-insured.
Important - Get an accurate contents valuation: New Zealanders often undervalue or overvalue their home contents. We recommend starting with Suncorp's contents calculator, which we explain in our video below.
In the video below, the contents insurance inventory process and MoneyHub template is explained:
Important: Understand the Hidden Risk Most Homeowners Don't Know They're Carrying
With sum insured, you're betting rebuild costs won't spike before you need to claim. History shows that this bet fails repeatedly when there is a natural disaster - Christchurch homeowners faced 40-70% cost spikes, leaving many with shortfalls of $200,000 or more, and the same happened after Gabrielle.
How Area Replacement Insurance Cover Eliminates This Risk:
Who Benefits Most from Area Replacement House Insurance Policies:
The MAS Difference: As a not-for-profit owned by members, MAS doesn't profit from claim denials or coverage gaps. They exist to pay claims, not protect shareholder profits. That's why they're the only insurer offering true area replacement.
Check Your Real Coverage Now: See how MAS area replacement protects you when sum insured cover is insufficient.
Important: The cheapest insurance is expensive if it leaves you $200,000 short. The best insurance - the kind that actually works - costs slightly more but delivers when disaster strikes.
With sum insured, you're betting rebuild costs won't spike before you need to claim. History shows that this bet fails repeatedly when there is a natural disaster - Christchurch homeowners faced 40-70% cost spikes, leaving many with shortfalls of $200,000 or more, and the same happened after Gabrielle.
How Area Replacement Insurance Cover Eliminates This Risk:
- No sum insured cap - Coverage based on your home's actual square meters, not a dollar guess - you can get a quote of the cost from MAS here.
- Automatic inflation protection - When building costs spike 40% after disasters, you're covered
- No annual revaluations needed - MAS, as the primary provider of area replacement, tracks rebuild costs, so you don't have to.
- Proven disaster performance - MAS customers rebuilt fully after Christchurch, floods, and Gabrielle - our MAS policyholder testimonials explains more.
Who Benefits Most from Area Replacement House Insurance Policies:
- Character home owners (impossible to value accurately)
- Anyone in disaster-prone areas
- Homeowners who want genuine "set and forget" insurance
- Those who understand that paying 10-20% more eliminates 100% of shortfall risk
The MAS Difference: As a not-for-profit owned by members, MAS doesn't profit from claim denials or coverage gaps. They exist to pay claims, not protect shareholder profits. That's why they're the only insurer offering true area replacement.
Check Your Real Coverage Now: See how MAS area replacement protects you when sum insured cover is insufficient.
Important: The cheapest insurance is expensive if it leaves you $200,000 short. The best insurance - the kind that actually works - costs slightly more but delivers when disaster strikes.
Case Studies - Adjusting the Sum Insured for Home, Home and Contents, and Contents Insurance Policies
We outline typical changes in sum insured after a change in circumstances:
Case Study 1: Home Insurance - Mark and Fiona
Case Study 2: Home and Contents Insurance - James and Emma
Case Study 3: Contents Insurance - Alex
Case Study 1: Home Insurance - Mark and Fiona
- Initial Rebuild Value: Mark and Fiona's home had an initial rebuild value of $500,000.
- Post-Renovation Update: After adding a second story to their home and installing solar panels, they updated their sum insured to $650,000.
- Factors Considered: Increased floor area, modern construction materials, quality of finishes and sustainable features such as solar panels
Case Study 2: Home and Contents Insurance - James and Emma
- Initial Rebuild Value: James and Emma's home had an initial rebuild value of $600,000.
- Post-Renovation Update: After converting their garage into a home office and upgrading their kitchen with high-end cabinets and appliances, they updated their sum insured to $750,000.
- Contents Insurance: Their initial contents sum insured was $100,000. After purchasing new office equipment, high-end kitchen appliances, and luxury furniture, they updated it to $150,000.
- Factors Considered: Increased floor area and new usage (home office), premium construction materials and appliances, value of new high-end contents and office equipment
Case Study 3: Contents Insurance - Alex
- Initial Contents Value: Alex's initial contents sum insured was $30,000.
- Post-Purchase Update: After acquiring an extensive home theatre system, a collection of vinyl records and an Apple Vision Pro, Alex updated his contents sum insured to $50,000.
- Factors Considered: Value of the home theatre system, the purchase price of the Apple Vision Pro and an appraised value of the vinyl collection
Calculating Sum Insured - Frequently Asked Questions
We have listed popular questions to help you understand the importance of 'sum insured' and why you need it to be accurate and reflective of your total rebuild cost.
Can my home insurer calculate my 'sum insured' or home replacement value?
No - it is the responsibility of the insurance policyholder to estimate their sum insured value. Every house is different, and for this reason, no insurer can estimate or provide direction for how much your house would cost to rebuild.
Reminder: Sum Insured cover is one of two ways to protect your home - you may also want to consider Area Replacement cover. Our guide to Sum Insured vs Area Replacement explains more.
Reminder: Sum Insured cover is one of two ways to protect your home - you may also want to consider Area Replacement cover. Our guide to Sum Insured vs Area Replacement explains more.
Is the home insurance calculator accurate?
The online calculator is provided by Cordell, New Zealand's leader in building replacement cost calculators. Cordell has a wealth of experience in overseas markets, and brings its technology to New Zealand, which is free to use.
The Cordell Sum Sure Calculator is used by thousands of people every year from all over New Zealand. While accuracy is at the heart of every calculation, the Cordell Online Sum Insured calculator does not consider every possible feature of a home. You are asked to specify any special features or additions your home has to make the quote more accurate. The true cost of replacing your home will depend on the specific details of your home.
Please note, the Cordell Online Calculator does not provide advice, it is merely an estimate, and you can choose to rely on it, or not.
The Cordell Sum Sure Calculator is used by thousands of people every year from all over New Zealand. While accuracy is at the heart of every calculation, the Cordell Online Sum Insured calculator does not consider every possible feature of a home. You are asked to specify any special features or additions your home has to make the quote more accurate. The true cost of replacing your home will depend on the specific details of your home.
Please note, the Cordell Online Calculator does not provide advice, it is merely an estimate, and you can choose to rely on it, or not.
What are the limitations of the house insurance calculator?
While the Cordell Online Calculator can estimate your sum insured, it won't be able to take into account 'special features' which can alter the cost of rebuilding. These include:
Be aware: if your sum insured does not cover all your potential costs, you could end up paying for them yourself.
- Added costs if your house is built on an uneven section or steep slope
- High-end luxury fittings
- Building consents for high-end properties
- Added costs involved with building in unique locations
Be aware: if your sum insured does not cover all your potential costs, you could end up paying for them yourself.
Why is accurately calculating my sum insured critical in a volatile construction market?
Rebuild costs can fluctuate significantly. Accurately calculating your sum insured ensures you have sufficient coverage to rebuild your home at current prices, protecting you from being underinsured and facing potential financial strain if construction costs are higher than what you've been paid out for.
What happens if my sum insured is too low?
If your sum insured is too low, you might not receive enough money to fully rebuild your home or replace your contents after a major loss. This shortfall can leave you with significant out-of-pocket expenses and may prevent you from restoring your home to its original or equal condition.
How often should I review my sum insured?
You should review your sum insured annually, particularly at policy renewal. Additionally, reassess your coverage after any major changes to your home, such as renovations, extensions, or significant purchases of high-value items.
Why should I consider professional assessments over online calculators for my sum insured?
Professional assessments by builders, architects, or quantity surveyors provide a tailored and precise estimate of your rebuild cost, considering all unique aspects of your home. This can be more accurate than online calculators, which might not account for specific features or local construction cost variations.
How does contents insurance handle high-value items?
Contents insurance typically covers items up to a certain limit per item (e.g., $3,000 for electronics). For high-value items (e.g., jewellery, art), you need to insure them as specified items, which requires declaring them separately and may increase your premium but ensures they are fully covered. Our guide to contents insurance has more information.
What is the difference between replacement cost and actual cash value in contents insurance?
Replacement cost coverage reimburses you for buying new items to replace lost or damaged ones. Actual cash value coverage reimburses you for the current value of the items, considering depreciation. Replacement cost coverage generally provides more comprehensive protection.
Can I use my home insurance sum insured amount to cover the contents as well?
No, home insurance and contents insurance are separate. Home insurance covers your home's structure and rebuild cost, while contents insurance covers personal belongings inside your home. Each requires its own sum insured to ensure comprehensive coverage.
How can I avoid common mistakes when calculating my sum insured?
To avoid common mistakes:
- Use detailed and accurate data for online calculators.
- Regularly update your sum insured to reflect any changes or additions to your home.
- Consider professional assessments for high-value or unique properties.
- Review your policy limits and specified item requirements for high-value belongings.
What should I do if my property has unique or historic features?
A standard online calculator may not provide an accurate estimate if your property has unique or historic features. In such cases, getting a professional assessment from a builder, architect, or quantity surveyor who can account for the specialised materials and craftsmanship required to rebuild or restore your property is helpful. Our guide to insuring old homes has more information.
How does inflation affect my sum insured, and what can I do about it?
Inflation increases the cost of materials and labour over time. To account for this, you should:
- Regularly review and adjust your sum insured.
- Consider policies with automatic inflation adjustments.
- Ensure your sum insured includes a buffer for future cost increases.
Important: Understand the Hidden Risk Most Homeowners Don't Know They're Carrying
With sum insured, you're betting rebuild costs won't spike before you need to claim. History shows that this bet fails repeatedly when there is a natural disaster - Christchurch homeowners faced 40-70% cost spikes, leaving many with shortfalls of $200,000 or more, and the same happened after Gabrielle.
How Area Replacement Insurance Cover Eliminates This Risk:
Who Benefits Most from Area Replacement House Insurance Policies:
The MAS Difference: As a not-for-profit owned by members, MAS doesn't profit from claim denials or coverage gaps. They exist to pay claims, not protect shareholder profits. That's why they're the only insurer offering true area replacement.
Check Your Real Coverage Now: See how MAS area replacement protects you when sum insured cover is insufficient.
Important: The cheapest insurance is expensive if it leaves you $200,000 short. The best insurance - the kind that actually works - costs slightly more but delivers when disaster strikes.
With sum insured, you're betting rebuild costs won't spike before you need to claim. History shows that this bet fails repeatedly when there is a natural disaster - Christchurch homeowners faced 40-70% cost spikes, leaving many with shortfalls of $200,000 or more, and the same happened after Gabrielle.
How Area Replacement Insurance Cover Eliminates This Risk:
- No sum insured cap - Coverage based on your home's actual square meters, not a dollar guess - you can get a quote of the cost from MAS here.
- Automatic inflation protection - When building costs spike 40% after disasters, you're covered
- No annual revaluations needed - MAS, as the primary provider of area replacement, tracks rebuild costs, so you don't have to.
- Proven disaster performance - MAS customers rebuilt fully after Christchurch, floods, and Gabrielle - our MAS policyholder testimonials explains more.
Who Benefits Most from Area Replacement House Insurance Policies:
- Character home owners (impossible to value accurately)
- Anyone in disaster-prone areas
- Homeowners who want genuine "set and forget" insurance
- Those who understand that paying 10-20% more eliminates 100% of shortfall risk
The MAS Difference: As a not-for-profit owned by members, MAS doesn't profit from claim denials or coverage gaps. They exist to pay claims, not protect shareholder profits. That's why they're the only insurer offering true area replacement.
Check Your Real Coverage Now: See how MAS area replacement protects you when sum insured cover is insufficient.
Important: The cheapest insurance is expensive if it leaves you $200,000 short. The best insurance - the kind that actually works - costs slightly more but delivers when disaster strikes.
