Loan Repayment Calculator
Work out your monthly, weekly or fortnightly loan repayment, total interest and total amount repayable for any personal loan, car loan or other fixed-term borrowing. Optionally add an extra payment or one-off lump sum to see the interest and time you could save.
This calculator uses a simplified annual-rate-divided-by-periods interest model. Actual lender calculations may differ due to fees, daily interest, or other account-specific terms.
Loan Summary
Loan Repayment Calculator: What Will This Loan Cost Me?
Our Loan Repayment Calculator answers one simple question: if you borrow a set amount at a set interest rate over a set term, what will your regular repayment and total interest be? Enter your loan amount, APR and term to get an instant answer for monthly, weekly, fortnightly or four-weekly repayments — plus an optional look at how an extra payment or one-off lump sum could reduce your total interest.
How This Differs From Our Personal Loan Calculator
This tool is intentionally simple. It does not compare lenders, loan offers or APR options, and there’s no multi-loan shopping workflow — for that, use our Personal Loan Calculator. This calculator is for when you already know the amount, rate and term you’re working with (or are considering) and just want a quick, accurate answer on repayments and interest.
How to Use the Loan Repayment Calculator
- Enter your loan amount — the amount you’re borrowing or already owe.
- Enter the interest rate (APR) as an annual percentage.
- Enter the loan term in years and months.
- Choose a repayment frequency — Monthly, Weekly, Fortnightly or Four-weekly.
- Optionally add an extra payment per period, a one-off lump sum, or both, to see the impact on your total interest and payoff date.
- Results update automatically, or click Calculate Repayments at any time.
Worked Example
Borrowing £15,000 at 8.9% APR over 5 years (60 monthly payments) gives a monthly repayment of £310.65, totalling £18,638.87 repaid — £3,638.87 of which is interest. Choosing weekly repayments instead (260 payments) works out at £71.53 per week, with slightly less total interest under this calculator’s simplified interest model (£3,596.84), because more frequent payments reduce the average balance that interest is calculated on.
| Scenario | Payments | Total Interest |
|---|---|---|
| Standard (no extra payment) | 60 monthly payments | £3,638.87 |
| +£50 extra per month | 50 monthly payments | £3,002.61 |
| +£2,000 lump sum at payment 12 | 52 monthly payments | £2,870.15 |
Adding £50 a month on top of the standard repayment clears the loan 10 months early and saves £636.26 in interest. A one-off £2,000 lump sum applied at the 12th payment saves even more — £768.72 — because it strikes while more of the balance is still outstanding.
How the Repayment Is Calculated
The calculator uses the standard loan amortisation (annuity) formula, which produces a fixed regular repayment that pays off the loan exactly over the chosen term, with each payment covering that period’s interest plus a portion of the remaining balance. Any extra payment or lump sum you add goes entirely toward reducing the outstanding balance, which reduces the interest charged in every subsequent period and can shorten the loan term.
Tips for Choosing a Loan Term and Repayment Frequency
- A shorter term means higher regular repayments but significantly less total interest — try a few different terms to see the trade-off.
- Under this calculator’s simplified interest model, more frequent repayments (weekly or fortnightly rather than monthly) can modestly reduce total interest because the average outstanding balance is slightly lower throughout the term.
- Check whether your lender allows overpayments or lump sum payments without an early repayment charge before relying on the extra payment feature.
- Even a small, regular extra payment compounds meaningfully over a multi-year term — re-run the calculator with different extra payment amounts to find one that fits your budget.
Frequently Asked Questions
How is my loan repayment calculated?
The regular repayment is calculated so that it repays the loan in full over your selected term. Each payment covers that period’s interest charge first, with the remainder reducing the outstanding principal — so the interest portion of each payment shrinks over time as the balance falls.
What is the difference between this and the Personal Loan Calculator?
This Loan Repayment Calculator is a quick, generic tool: enter an amount, rate and term to see your repayment and total interest. It doesn’t compare lenders or loan offers. The Personal Loan Calculator is more comprehensive and is aimed at comparing different rates, terms and fees when shopping for a new loan.
Does paying weekly or fortnightly save money compared to monthly?
Yes, slightly. Under this calculator’s simplified interest model, paying more frequently reduces the average outstanding balance over the term, which means marginally less interest accrues, even though the annual interest rate is the same. The difference is usually modest — in our worked example, switching from monthly to weekly repayments on the same loan saved about £42 in total interest. Real lenders don’t all calculate interest the same way, so your actual saving from a different frequency may differ from this estimate.
What happens if I add an extra payment or lump sum?
Your regular scheduled repayment stays the same, but any extra payment or lump sum is applied directly to the outstanding balance. This reduces the interest charged on all future payments and can significantly shorten how long it takes to repay the loan, as shown in the comparison table after you calculate.
Can I use this for a car loan or only a personal loan?
This calculator works for any fixed-rate, fixed-term loan with regular repayments — personal loans, car loans, or similar borrowing. It is not designed for mortgages, which typically involve additional costs like stamp duty; use our Mortgage Calculator for those.
Is the interest rate here APR or a simple annual rate?
This calculator uses a simplified interest model based on your entered annual rate divided evenly across the periods in a year. It closely approximates how many fixed-rate loans work but will not exactly match every lender’s calculation, particularly where fees, daily interest, or other account-specific terms apply. Check your loan agreement for the exact method used.
Where should I apply a lump sum for the biggest interest saving?
Generally, the earlier in the loan term you apply a lump sum, the more interest it saves, because it reduces the balance while a larger amount is still outstanding and accruing interest. Try entering a few different payment numbers to compare the effect on your specific loan.
Does this calculator account for arrangement fees or early repayment charges?
No. This calculator focuses purely on principal, interest rate and term. If your loan has an arrangement fee, add it to your loan amount to include it in the calculation, and check your loan agreement separately for any early repayment charges that could offset the interest savings from extra payments.