Calculate repayments, total interest cost, and see if the loan fits your budget. Compare loan types including novated leases and balloon payments.
| Month | Repayment | Interest | Principal | Balance |
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How your rate compares to typical Australian lenders (personal loan, March 2025):
Every amortising loan repayment splits between two things: interest charged on the current balance, and principal that reduces the balance. Each month the lender calculates interest on what you still owe, deducts it from your payment, and applies whatever's left to the principal. Next month the interest is calculated on a slightly smaller balance, so a slightly larger share of the same monthly payment goes to principal.
The Australian Securities and Investments Commission requires lenders to publish a comparison rate alongside the advertised rate, to capture fees the headline rate excludes. The two often diverge by 1–2 percentage points. The comparison rate is the one to use when comparing lenders.
The lever consumers most often see at a dealership, bank, or comparison website is loan term. Stretching a loan from three years to seven years cuts the monthly payment by about half. Total interest paid more than doubles.
A $30,000 personal loan at 8% costs $940 a month over three years and $3,842 in total interest. Stretch the same loan to five years and the monthly payment drops to $608 while total interest rises to $6,497. Stretch it again to seven years and the monthly payment falls to $467 while interest climbs to $9,267 — almost two and a half times the three-year cost for the same money borrowed.
Whether the lower monthly payment is worth it depends on what the freed-up cash does. If the answer is "nothing in particular, the budget just feels easier," the trade is usually expensive.
The headline figure is the regular repayment — what comes out of your account each pay cycle. Beneath it, total interest shows the lifetime cost of borrowing, and total cost shows principal plus interest combined.
Weekly versus monthly repayments produce a small interest difference because most lenders calculate interest daily. Paying principal slightly earlier in each month reduces the interest charged for the rest of that month. The effect is modest at typical personal-loan rates.
Balloon payments, common in novated leases and some car loans, leave a lump sum owing at the end of the term. The monthly payment is lower because principal isn't fully repaid, but total interest paid is higher than an equivalent fully amortising loan.
This calc covers the standard amortisation maths. It does not capture:
Use this calc for the headline maths. Use each lender's comparison rate for accurate side-by-side comparison.
What is a comparison rate, and why does it differ from the advertised rate?
The comparison rate is mandated by the National Consumer Credit Protection Act to include the headline interest rate plus most ongoing and upfront fees. The advertised rate excludes fees. Two loans with identical advertised rates can have very different comparison rates.
Does paying weekly really save money compared to monthly?
A small amount. Most lenders calculate interest daily, so paying principal earlier in each month reduces the interest accrued for the rest of that month. The saving is real but modest at typical personal-loan rates.
Does paying extra early matter more than paying extra late?
Yes. An extra payment in year one of a five-year loan saves more total interest than the same payment in year five, because the early payment reduces the balance for longer.
For a home loan, the same amortisation maths runs over 25–30 years and the early-years interest dominance becomes much more pronounced — the mortgage calculator handles that scale. To see how the same home loan gets repaid faster with cash sitting in an offset account, see how offset accounts actually work. For interest working in your favour rather than against you, the compound calculator is the inverse.