01 / START WITH YOUR NUMBERS
How to use the personal loan calculator
Choose an amount
Enter the sum you want to explore. The accepted range is a calculator limit, not an indication that you can obtain a loan for that amount.
Enter an APR and term
Use a personalised APR if you have one. Otherwise try illustrative rates and see how the result changes. The default 7.9% is a starting example, not a current offer.
Add your own monthly budget
Enter the amount you want to compare with the repayment. The result shows whether the payment is above or below it. You still need to consider income, commitments and unexpected costs separately.
02 / THE NUMBERS IN PRACTICE
A worked example
The default illustration compares a £10,000 loan over five years at 7.9% APR with a £250 monthly repayment budget. It assumes fixed payments and no separately added fees.
£200.99
- Amount borrowed
- £10,000.00
- Total interest
- £2,059.19
- Total to repay
- £12,059.19
- Your entered monthly budget
- £250.00
Fixed illustration using the starting inputs, separate from the live calculator above. Displayed amounts are rounded.
Uses an effective annual APR converted to a monthly rate, with equal payments at month-end. Fixed rate, no additional fees. Starting rates are examples, not offers.
03 / UNDERSTAND YOUR RESULT
The budget comparison has a narrow purpose
The calculator subtracts the estimated monthly payment from the budget you enter. A positive difference means the payment is below that figure. It does not mean the loan is affordable, suitable or likely to be approved.
For example, a £200 payment is £50 below a £250 budget. The calculator cannot know whether the £250 budget itself is realistic. This distinction matters when comparing a payment with a number that has not yet been checked against regular outgoings.
04 / UNDERSTAND YOUR RESULT
Compare the cost across the whole term
For a fixed amount and positive APR, a longer term normally reduces each payment and increases interest paid overall. The term cards show that trade-off with the same entered amount and rate. They do not suggest which term you should choose.
An advertised representative APR is not necessarily the rate offered to you. Once you receive a quote, compare its total repayment and payment schedule rather than relying on the illustrative figure. MoneyHelper provides further information on personal loans and APR.
PLAIN ENGLISH, PLEASE
Personal loan glossary
The terms behind the inputs and results, explained without the guesswork.
- Personal loan
- A loan taken for personal use. This calculator models equal monthly repayments over a fixed term.
- APR
- Annual percentage rate, an annual borrowing-cost measure. Here it is treated as an effective annual rate.
- Principal
- The amount borrowed before interest, shown as the loan amount.
- Repayment budget
- The monthly figure you enter for comparison. It is not a lender's assessment.
- Total interest
- The sum of unrounded repayments less the amount borrowed.
- Term
- The full repayment period, converted into monthly payments by multiplying years by 12.
BEHIND THE ESTIMATE
How the calculation works
We convert the APR into a monthly equivalent using (1 + APR ÷ 100) raised to 1/12, minus one. A standard amortising formula then sets the payment that clears the balance over the term.
At zero APR, the payment is amount divided by months. Budget difference is entered budget minus monthly payment. No other debts, taxes, charges, missed payments or changes in rate are included. Totals use unrounded instalments, so displayed payments can differ by a few pence when multiplied.
Sources and further reading
Examples use Switcha’s calculation model above. Supporting information and linked guidance checked on 10 September 2026.