Loan Repayment Calculator with Amortisation
Monthly repayment, total interest and an amortisation schedule.
Use via API
Fixed-rate loan or mortgage repayment: monthly payment, total interest, total repaid, a yearly amortisation summary and optionally the full monthly schedule. Send JSON, get JSON back.
POST https://pithlab.com/api/v1/tools/loan-calculator
curl https://pithlab.com/api/v1/tools/loan-calculator \
-H "Authorization: Bearer $PITHLAB_KEY" \
-H "Content-Type: application/json" \
-d '{"amount":200000,"rate":6,"term":30,"termUnit":"years"}'About the Loan Calculator
Calculate the monthly repayment, total interest and total cost of a fixed-rate loan or mortgage, with a yearly amortisation table and CSV export.
How to use the Loan Calculator
- Enter the amount borrowed and the annual interest rate.
- Enter the term in years or months.
- Read the monthly repayment and total interest, then check the yearly table or download the full monthly schedule as CSV.
Examples
Input
200000, 6%, 30 years
Output
Monthly payment 1,199.10 for 360 months: total interest 231,676.38, total repaid 431,676.38
Input
10000, 5%, 5 years
Output
Monthly payment 188.71 for 60 months: total interest 1,322.74, total repaid 11,322.74
Frequently asked questions
How is the monthly payment calculated?
With the standard amortisation formula M = P × i ÷ (1 − (1 + i)^−n), where P is the amount borrowed, i the annual rate divided by 12, and n the number of monthly payments.
Why is most of the early payment interest?
Interest is charged on the balance still owed. At the start the balance is highest, so more of each fixed payment goes to interest and less to the principal. The split reverses over the term.
Will my lender's figure match exactly?
It may differ slightly. Lenders can round payments, charge fees, use an APR that includes costs, or calculate interest daily. Use this as an estimate and check the lender's official illustration.