Credit Card Interest Calculator
Updated 31 August 2026
Important: This calculator was relaunched in August 2026. Its default rates and the figures in this guide were checked against issuers' published terms. Rates change, so use your own card's rate from your statement. Report an error on this page - no name or email needed.
Summary
Important: This calculator was relaunched in August 2026. Its default rates and the figures in this guide were checked against issuers' published terms. Rates change, so use your own card's rate from your statement. Report an error on this page - no name or email needed.
Summary
- Our credit card calculator works out how long it will take you to pay off your current credit card balance, and the total interest you'll pay.
- Just enter your balance, interest rate and how much you usually pay off each month and let us do the work.
- Know This: If you want to reduce your interest costs, ask your bank to lower your credit limit so the balance can't creep back up. The less you owe, the less interest you pay and the sooner it's gone.
Credit Card Interest Calculator - with balance transfer comparison
Work out how long your current card will take to clear and what it will cost in interest, then compare it with a balance transfer card.
Current card
Time to pay off
2 years 11 months
Total interest
$1,866
Total cost
$6,866
vs
Balance transfer card
Time to pay off
2 years 4 months
Interest + fees
$499
Total cost
$5,499
A balance transfer would save you $1,367
By switching to a 0% balance transfer card, you would clear the debt 7 months faster and save around $1,367 in interest. Some debt remains after the promo period ($3,800) and reverts to 13.5%. Compare current NZ balance transfer offers.
Time saved
7 months
Total savings
$1,367
In interest
Balance after promo ends
$3,800
After 6 months at 0%
Important balance transfer rules: You cannot transfer between cards from the same bank. Don't make new purchases on the new card during the promo (they often attract the standard rate). After the promotional period ends, any remaining balance reverts to the card's standard rate (12.90% to 13.90% p.a. on the current balance transfer cards). For the best result, work out your monthly payment as balance ÷ promo months to clear it before the promo ends.
MoneyHub Founder Christopher Walsh explains how to use our credit card interest calculator in the video below:
Paying off a large balance? Consider a balance transfer.
If your balance is over $5,000 and will take more than a few months to clear, a balance transfer card can cut the interest substantially - 0% for six months on the current offers, or 1.99% for up to 24 months. It only works if you pay it down during the promotional period and don't spend on the new card.
Credit Card Interest Frequently Asked Questions
We have listed a number of credit card interest and payment FAQs to help you navigate to a lower credit card balance.
Why am I being charged interest on my credit card?
Interest is charged when you don't fully pay off your credit card balance on the due date. For example, if your statement says $4,000 is due on 15 March and you only pay $500, you will pay interest on the $3,500 that is unpaid. You will be charged interest until the balance is fully repaid.
Interest is charged when you don't fully pay off your credit card balance on the due date. For example, if your statement says $4,000 is due on 15 March and you only pay $500, you will pay interest on the $3,500 that is unpaid. You will be charged interest until the balance is fully repaid.
How is credit card interest calculated in New Zealand?
Interest is calculated daily and charged to a balance at the end of the month if you do not pay off the entire balance. For example, if you have a credit card with an interest rate of 24% p.a. and a $1,000 balance to pay that is overdue, you will pay 2% per month (calculated as 24% / 12 months) on the balance until it is repaid. This works out to $20 per month, or $240 a year. The higher the interest rate and the larger the balance owed, the more dollars you will spend on making interest payments.
Interest is calculated daily and charged to a balance at the end of the month if you do not pay off the entire balance. For example, if you have a credit card with an interest rate of 24% p.a. and a $1,000 balance to pay that is overdue, you will pay 2% per month (calculated as 24% / 12 months) on the balance until it is repaid. This works out to $20 per month, or $240 a year. The higher the interest rate and the larger the balance owed, the more dollars you will spend on making interest payments.
When should I pay my credit card bill to avoid interest?
Pay the full closing balance by the due date on your statement - that's the only way to avoid interest. If you're carrying a balance, paying earlier does help, because interest accrues daily.
Pay the full closing balance by the due date on your statement - that's the only way to avoid interest. If you're carrying a balance, paying earlier does help, because interest accrues daily.
Do you get charged interest if you pay minimum payment?
Yes - you will be charged interest on the balance that remains unpaid. For example, if your balance is $1,000 and the minimum payment is 5% and you make a $50 payment, you will pay interest on the $950 owing. Because you didn't pay in full, most cards also cancel the interest-free period on your purchases, so interest is charged from the date of each purchase, not just on the $950.
Yes - you will be charged interest on the balance that remains unpaid. For example, if your balance is $1,000 and the minimum payment is 5% and you make a $50 payment, you will pay interest on the $950 owing. Because you didn't pay in full, most cards also cancel the interest-free period on your purchases, so interest is charged from the date of each purchase, not just on the $950.
What is the average credit card interest rate?
Standard rewards cards charge 18.95% to 22.95% p.a., low interest cards 9.95% to 13.90% p.a., and store cards 28.95% to 29.49% p.a.
Standard rewards cards charge 18.95% to 22.95% p.a., low interest cards 9.95% to 13.90% p.a., and store cards 28.95% to 29.49% p.a.
Does getting charged credit card interest affect your credit score?
Not by itself. Credit reporting in New Zealand records whether you made at least the minimum payment on time; carrying a balance and paying interest isn't a negative event, but missing a payment or paying late is. A large balance relative to your limit can still count against you when you apply for new credit. Our guide to credit scores has more information.
Not by itself. Credit reporting in New Zealand records whether you made at least the minimum payment on time; carrying a balance and paying interest isn't a negative event, but missing a payment or paying late is. A large balance relative to your limit can still count against you when you apply for new credit. Our guide to credit scores has more information.
What is a good interest rate on a credit card?
A 'good' interest rate is 0%, which is available for up to 6 months with a balance transfer credit card. Otherwise, the lower the percentage, the better the credit card all other things being equal. A competitive interest rate is one from the low interest cards - our guide to low interest credit cards has more information.
A 'good' interest rate is 0%, which is available for up to 6 months with a balance transfer credit card. Otherwise, the lower the percentage, the better the credit card all other things being equal. A competitive interest rate is one from the low interest cards - our guide to low interest credit cards has more information.
How do I get my bank or credit card company to lower my interest rate?
Banks don't negotiate credit card rates. Your options are moving to a low interest card (with the same bank or another), a balance transfer, or - if you're struggling - asking your bank for a hardship arrangement.
Banks don't negotiate credit card rates. Your options are moving to a low interest card (with the same bank or another), a balance transfer, or - if you're struggling - asking your bank for a hardship arrangement.
