Published 13 July 2026
Loan repayment calculator
Work out repayments on a personal or general-purpose loan, and what it costs in interest.
How are loan repayments calculated?
Every amortised loan prices the same way: home, car, personal or renovation. A fixed instalment pays the period's interest first. Whatever is left comes off the balance. The instalment is sized so the debt reaches zero exactly at the end of the term.
The rate per period is the annual rate divided by the number of repayments in a year. Interest is charged on the balance still owing. Early instalments are therefore mostly interest. Later ones mostly repay the amount borrowed.
What interest rate should the calculator use?
A real quote beats any assumption. For this kind of loan, quotes are the only honest source. The RBA's published average for unsecured personal term loans ended in February 2020. So official data for a typical rate is unavailable. What the RBA still publishes brackets the range. Secured lending sits lowest. Discounted variable owner-occupier housing rates averaged 6.8 per cent in June 2026. Credit cards sit highest. Low-rate cards averaged 13.49 per cent, and standard cards 20.99 per cent.1 Unsecured personal term loans generally price between those poles. That is where the example default sits.
The rate moves the total more than the repayment. Take the gap between the card average of 13.49 per cent and the secured average of 6.8 per cent. On the worked example, it is worth $99 a month. Over the five years, it is worth $5,936 of interest (illustrative calculations at those two published averages). Security, in other words, is expensive to do without.
How much does a shorter term save?
Cutting the worked example from 5 years to 3 saves $3,208 of interest (rounded from the difference of the exact figures). The repayment rises from $630 to $961 a month. Total interest falls from $7,803 to $4,596. The saving is the reward for the discipline of the higher instalment.
Short terms suit mid-size loans better than they suit mortgages. The instalment jump is absolute dollars, not a proportion. An extra few hundred dollars a month retires a car-size debt years earlier.
The trap runs the other way too. Stretching a mid-size loan across a long term makes the repayment look painless. It also multiplies the interest. On purchases that lose value, the loan can outlast the thing it bought. The chart above makes the trade visible. The flatter the balance line falls, the larger the area under the interest line grows.
What does the calculator leave out?
Fees, first of all. Establishment fees, monthly account fees and early-exit charges all sit outside the arithmetic. On smaller loans they matter more, because a fee is a bigger share of a small loan's cost. A modest monthly fee on the worked example's loan would add a meaningful fraction of its total interest. That is why comparison rates exist: they fold fees into one advertised rate. Those are lender-specific figures. They belong on a quote, not in a general calculator.
Variable rates can also change at any time. This projection holds one rate for the whole term.
The calculator also says nothing about approval. Lenders look at income, expenses, existing debts and credit history before offering an amount and a rate. The figures here are the mathematics of the numbers entered. They help test a quote or compare loan structures. They do not predict what any lender would offer. For home purchases specifically, the home loan calculator starts from the price and deposit instead.
Loan repayment questions
What are the repayments on a $30,000 loan?
At 9.5 per cent over 5 years, $630 a month (worked example). Interest over the term comes to $7,803. The calculator reworks both figures for any amount, rate, term and repayment frequency.
How much loan repayment is there per $10,000 borrowed?
About $210 a month, at 9.5 per cent over 5 years (worked example). Repayments scale in a straight line with the amount. So that figure multiplies out to any loan size at the same rate and term.
What is a typical personal loan interest rate?
No current official average exists. The RBA discontinued its unsecured personal term-loan series in February 2020. Its published June 2026 averages bracket the range. Discounted secured housing lending averaged 6.8 per cent. Credit cards averaged 13.49 and 20.99 per cent. Unsecured term loans generally price between them.
Does paying weekly or fortnightly reduce interest?
Only marginally, when the instalment is recalculated properly, as this calculator does. More frequent, smaller payments service the same balance at the same annual rate. The well-known saving comes from a different habit: paying half a monthly instalment each fortnight. That adds one extra monthly payment a year. So it is really an extra-repayment strategy.
Is a loan repayment calculator the same for car and personal loans?
The mathematics is identical for any amortised loan. The inputs are what differ. Car loans often carry balloon payments, a lump sum left owing at the end, plus secured rates. Home loans price lower again, over much longer terms. This page handles the general case. Product-specific structures get their own calculators.
References
- RBA, Indicator Lending Rates (Statistical Table F5)Reserve Bank of AustraliaPublished 2026-06-01 · Retrieved 2026-09-10