Loan Repayment Calculator with Overpayments
Enter a loan amount, rate and term to see the monthly payment, the total interest and a full amortisation schedule. Add a regular overpayment or one-off lump sums to see how much interest and time they save. Or start from what you can afford each month and find out how long the loan will take.
Overpayments
Extra payments go straight to the balance. See how much interest and time they save.
Balance over time
Amortisation schedule
What Loan Calculator does
See what overpaying is worth
Add an extra amount each month, or one-off lump sums, and see the interest saved and how much sooner you are debt-free — compared against the same loan without them.
Start from your budget
Know what you can afford each month but not the term? Enter the payment and get the number of months, the payoff date and the total interest.
A schedule that adds up
Interest is rounded to the penny each month, the way a lender's statement is, and the final payment absorbs the rounding — so every column sums exactly to the totals.
The right kind of rate
Choose a nominal annual rate, used on most loan contracts, or an effective annual rate such as a UK APR. Mixing them up changes the answer.
Balance over time
A chart of the remaining balance, with and without your overpayments, makes the difference visible at a glance.
Take the schedule with you
Switch between yearly and monthly views, and export every payment to a CSV file for a spreadsheet.
How it works
Enter the loan
Amount, interest rate and whether that rate is nominal or an APR.
Set the term or budget
Give the term in years and months, or the monthly payment you can manage.
Add overpayments
A regular extra amount, or one-off payments at a given payment number.
Read the result
Monthly payment, total interest, payoff date and savings — then check the schedule or export it.
Cheatsheet
The tokens you reach for most, at a glance.
PrincipalThe amount borrowed, or the part of it still owedNominal rateAnnual rate divided by 12 to get the monthly rateAPR (UK)Effective annual rate including compounding and some feesAmortisationRepaying a loan through regular payments of interest plus principalOverpaymentAnything paid above the scheduled payment; it reduces principal directlyTermThe number of monthly payments until the balance reaches zeroHow people use it
Mortgages
See how a small monthly overpayment shortens a 25- or 30-year mortgage, and when a lump sum does the most good.
Car and personal loans
Compare terms before you sign: a longer loan lowers the payment but raises the total interest.
Student loans
Work out how long a fixed monthly payment will take to clear a balance.
Budgeting
Start from what you can afford each month and see what size loan and term that supports.
Frequently asked questions
How is the monthly payment calculated?
With the standard amortisation formula: payment = P × r ÷ (1 − (1 + r)−n), where P is the amount borrowed, r the monthly rate and n the number of payments. Each month interest is charged on the remaining balance and the rest of the payment reduces it — which is why early payments are mostly interest.
Should I enter the APR or the interest rate?
Enter whatever your loan documents give, and set "Rate is" to match. Most contracts, and US lenders, quote a nominal annual rate, which is divided by 12. A UK APR is an effective annual rate that already includes compounding (and sometimes fees), so its monthly rate is slightly lower — choose "Effective annual / UK APR" for it.
How much do overpayments save?
Often more than people expect, because every extra payment removes principal that would otherwise have been charged interest for the rest of the term. On a $300,000 mortgage at 6% over 30 years, an extra $200 a month saves about $91,000 in interest and clears it 6 years and 9 months early. The earlier the overpayment, the bigger the effect.
Is it better to overpay monthly or in a lump sum?
Money paid earlier saves more, whichever form it takes: a lump sum in year one beats the same amount spread over the following years. In practice, check your loan's terms first — some limit overpayments to a share of the balance each year or charge an early repayment fee.
Why doesn't the last payment match the others?
Payments are rounded to the penny, so a tiny difference builds up over the term. The final payment absorbs it and the balance ends at exactly zero. With overpayments, the last payment is simply whatever is left.
Is my loan information stored or sent anywhere?
No. Every figure is calculated in your browser. Nothing you enter is uploaded, stored or added to the page address, and the CSV is created on your device.
Last updated 2026-09-12