Personal loan calculator
Estimate repayments and total cost — including establishment fee — for an unsecured personal loan.
Calculator loansLogic updated April 2026
This calculator estimates the regular repayment, total interest, and full amortisation of an unsecured personal loan. It uses standard amortisation on the financed amount — your principal plus any establishment fee that the lender folds into the loan — so the repayment figure reflects what actually leaves your account each period.
How this is calculated
Formula
M = F × [r(1+r)^n] / [(1+r)^n – 1] where F = principal + establishmentFeeStep-by-step
- Add the establishment fee to the principal — this is the financed amount you actually pay interest on
- Convert the annual rate to a periodic rate by dividing by the number of repayments per year
- Calculate the total number of repayments (term in years × payment frequency)
- Apply the standard amortisation formula to determine the fixed periodic payment
- Multiply the periodic payment by the total number of periods to get the total repaid, then subtract the principal to derive the total interest
- Rounding mode
- ROUND_HALF_UP
- Precision
- 20-digit internal precision (Decimal.js), rounded to 2 decimal places for display
- Logic last reviewed
Assumptions & limitations
What this calculator assumes
- Fixed interest rate for the loan term
- Repayments are made at the end of each period
- Establishment fee is financed into the loan principal
- No ongoing monthly fees are included
- Unsecured loan — no collateral considered
What this calculator doesn’t account for
- Does not include ongoing account-keeping or annual fees
- Does not model variable-rate movements during the term
- Does not include early-payout penalties or break costs
- Does not factor in optional insurance products often offered alongside personal loans
- Does not compare against the lender's comparison rate, which would include all fees
Worked example
A borrower takes out a 5-year unsecured personal loan for $20,000 at 9.5% with a $400 establishment fee financed into the loan, paid monthly.
| Input | Value |
|---|---|
| Principal | $20,000 |
| Establishment fee | $400 |
| Interest rate | 9.5% |
| Loan term | 5 years |
| Repayment frequency | Monthly |
Monthly repayment: $428.93 — Total interest: $5,335.80
The financed amount is $20,400 ($20,000 plus the $400 fee). At 9.5% over 60 monthly payments, that produces a fixed payment of about $428.93 and a total repaid of $25,735.80. Subtracting the original $20,400 financed amount gives $5,335.80 of interest. The fee shows up as part of the financed balance, so you pay interest on it too.
Frequently asked questions
How is personal loan interest calculated?
Personal loans use standard amortisation: each repayment covers the interest accrued on the current balance plus a portion of principal, with the principal share growing each period as the balance shrinks. The interest rate is applied periodically (e.g. monthly), so a 9.5% annual rate becomes roughly 0.79% per month.
Fixed vs variable rate — which is better?
Fixed-rate loans give you a known repayment for the full term — useful for budgeting. Variable-rate loans can move up or down with the market, so they're cheaper if rates fall but riskier if rates rise. Most personal loans default to fixed because the term is short enough that lenders are happy to lock in pricing.
What affects my interest rate?
Lenders price personal loans on credit history, income stability, debt-to-income ratio, loan amount, term, and whether the loan is secured. Borrowers with stronger credit profiles routinely get rates several percentage points below headline 'comparison rates'. Shopping around — and getting written quotes — typically beats accepting the first offer.
How does loan term affect total cost?
Longer terms reduce the monthly repayment but increase the total interest paid because the balance stays elevated for longer. Shorter terms cost more per month but less in total. As a rule of thumb, going from 7 years to 5 years on the same loan often cuts total interest by 25–35%, even though the monthly payment rises only modestly.
Can I pay off a personal loan early?
Most personal loans allow early repayment, but some charge break fees if the loan is fixed-rate. This calculator doesn't model break costs — check your loan agreement. Even with a small break fee, paying off a personal loan early usually saves more in interest than the fee costs.
Embed this calculator
Add this calculator to your website. Free to use with attribution.
The calculator will resize to fit your content area. Please keep the attribution link visible — replace YOUR_SITE with your domain so we can attribute traffic correctly.