Personal Loan Amortization Calculator
Use this calculator to find your exact monthly payment on a personal loan and see how each payment is split between interest and principal. The amortization formula is the standard calculation used by US consumer lenders under the Truth in Lending Act: M = P * r * (1+r)^n / ((1+r)^n - 1), where P is the loan amount, r is the monthly interest rate, and n is the total number of monthly payments. Understanding your amortization schedule helps you see exactly how much interest you will pay over the life of the loan and how much equity you build with each payment.
Amortization formula
M = P * r * (1+r)^n / ((1+r)^n - 1)
Where M is the monthly payment, P is the principal loan amount, r is the monthly interest rate (annual rate / 12 / 100), and n is the number of monthly payments (years * 12). Total interest = (M * n) - P.
Understanding your amortization schedule
In the early months of a loan, a larger share of your payment goes toward interest. This is because interest accrues on the full outstanding balance. As you pay down the principal, the interest portion shrinks and the principal portion grows. This is why making extra payments early in a loan saves the most interest. The CFPB recommends comparing loans by APR, which includes fees, not just the stated interest rate.
Frequently asked questions
What is an amortizing loan?
An amortizing loan has fixed periodic payments that cover both interest and principal. Early payments are weighted toward interest; later payments reduce more principal. By the final payment, the balance reaches zero.
How is the monthly payment calculated?
Monthly payment M = P * r * (1+r)^n / ((1+r)^n - 1), where P is the principal, r is the monthly rate (annual rate / 12), and n is the number of monthly payments.
What does the amortization schedule show?
Each row shows the payment number, payment amount, interest portion, principal portion, and remaining balance. The interest portion decreases and the principal portion increases with each payment.
Does this calculator include fees or insurance?
No. This calculator uses the standard amortization formula for principal and interest only. Add any origination fees, insurance, or taxes separately to get the full cost of borrowing.
What is the Truth in Lending Act (TILA) requirement for lenders?
Under TILA (15 U.S.C. 1601 et seq.), lenders must disclose the APR, total finance charge, amount financed, and total of all payments before you sign. Review these disclosures and compare them to this calculator's output.
Official sources
- Consumer Financial Protection Bureau (CFPB): Personal Loans.
- Federal Reserve: Consumer Credit (G.19 Release).
- Truth in Lending Act (TILA), 15 U.S.C. 1601 et seq., implemented by Regulation Z: 12 CFR Part 1026.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.