Loan Calculator
Work out the instalment on any amortizing loan, at monthly, fortnightly, weekly or quarterly repayments.
Please note: An estimate, not a quote or financial advice. A lender’s actual offer depends on your credit assessment, and fees such as arrangement or early-settlement charges are not included unless you enter them.
What the Loan Calculator does
An amortizing loan is repaid in equal instalments that cover the interest accrued since the last payment first, and reduce the principal with whatever is left. This calculator finds that level instalment for any repayment frequency — monthly, fortnightly, weekly or quarterly — and shows how the balance falls. Repaying more often costs less overall, because interest is charged on a balance that has already been reduced.
Formula
A = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)where r = annual rate ÷ payments per year ÷ 100, and n = term in years × payments per yearAverage monthly outlay = A × payments per year ÷ 12
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Loan amount | selected currency | Yes | Accepts more than 0. |
| Annual interest rate | % | Yes | — |
| Loan term | years | Yes | Accepts 0 or more, up to 50. |
| Repayment frequency | one of 4 options | Yes | — |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Repayment frequency and Currency.
- Enter Loan amount, Annual interest rate and Loan term.
- Select Calculate.
Worked example
Borrowing $25,000 over 5 years at 7.5%, repaid fortnightly instead of monthly.
- Loan amount
- 25000
- Rate
- 7.5
- Term
- 5
- Frequency
- Fortnightly (every 2 weeks)
Fortnightly payment $230.89 across 130 repayments, total interest $5,015.41 — $41.52 less than the $5,056.92 the same loan costs repaid monthly, and about $500.26 a month either way.
Reading the result
- The monthly payment is fixed, but its composition is not: the interest share falls and the principal share rises with every payment made.
- Total interest is the real cost of borrowing. Judge a loan on that figure together with the rate, not on the monthly payment alone.
- Any overpayment goes entirely against principal, so it removes all the future interest that principal would have generated — the earlier it lands, the more it saves.
Assumptions and limitations
- A fixed rate for the full term, with equal payments and no missed or early payments.
- Fees such as arrangement or origination charges are only included if you entered them; they materially change the true annual cost.
- The schedule assumes interest accrues on the standard monthly cycle, which some lenders vary with daily accrual.
Common mistakes
- Entering the term in months where years are expected, or the reverse.
- Comparing a quoted rate against an APR from a different lender. APR includes fees; a bare interest rate does not.
- Assuming a longer term is cheaper because the monthly figure is lower — it almost always costs more in total interest.
Frequently asked questions
Does paying fortnightly really cost less?
Yes, though less dramatically than often claimed. Interest accrues on the outstanding balance, so reducing that balance every two weeks instead of every month means slightly less interest accrues. The saving here comes only from the timing. A bigger saving is sometimes quoted for "fortnightly" schemes that actually take half the monthly payment 26 times a year — that is 13 monthly payments, so most of the benefit is the extra payment, not the frequency.
Why is so much of my early payment interest?
Interest is charged on the outstanding balance, which is highest at the start. As the balance falls, the interest portion of each fixed payment shrinks and the principal portion grows.
Should I choose a shorter term?
A shorter term raises the instalment but lowers total interest substantially. The useful question is the shortest term whose payment you can sustain without needing to borrow again.
What does this calculator not cover?
Fees, insurance and any charge outside the instalment itself. It also assumes the rate is fixed for the whole term — on a variable rate the instalment or the term will move. For a monthly instalment quoted on a flat rate, use the EMI calculator; to work back from a property price and deposit, use the home loan calculator.
Method and sources
Method. The standard amortizing-loan formula: the level payment that covers accrued interest first and reduces principal with the remainder, sized so the balance reaches exactly zero at the final payment.
Limitations
- No external rate table or lender data is used — every figure comes from what you entered, so the result is only as accurate as the rate and term you supply.
- The formula assumes a fixed rate for the full term. A variable or tracker rate produces a schedule this calculator cannot predict.