Loan calculator
Estimate a monthly loan payment, total repayment and overpayment.
Fill in the fields and the result will appear here automatically.
A smaller loan payment can hide a longer term and a higher interest bill. This calculator separates the base payment, loan interest, an entered one-time fee and the effect of a fixed monthly extra payment. An annuity keeps the base payment constant; equal-principal repayments keep the principal component constant. The schedule shows how each actual payment is split between interest and principal.
How it works
Formula and logic
Let P be the principal, n the number of months and r = annual interest rate / 100 / 12. The annuity payment is A = P × r / (1 − (1 + r)^−n); at zero interest, A = P / n. Each month, interest equals outstanding principal × r, and the rest of the payment repays principal. With equal-principal repayments, the base principal component is P / n. A monthly extra payment shortens the term while the base scheduled payment stays fixed. The final actual payment is capped at principal and interest still due. An entered one-time fee adds once to total repayment and extra cost; it is not financed and does not increase loan interest. Every month represents one twelfth of a year. Values are rounded only for display, so adding rounded schedule cells can differ from the rounded total.
Example
These illustrative amounts use currency units. For 120,000 over 12 months at a nominal 12% annual rate with equal-principal repayments, r is 1% and monthly principal repayment is 10,000. The first payment is 10,000 + 1,200 = 11,200; the last is 10,000 + 100 = 10,100. Interest totals 7,800. A one-time fee of 300 makes total repayment 128,100 and extra cost 8,100. Boundary case: at 0% over the same term, the annuity payment is 10,000. A fee of 2,500 leaves interest at zero but makes total repayment 122,500.
Fields and units
- Amount — $
- Term — months / years. The term must total 1 to 1200 whole months. Fractional years are allowed when they give whole months: 1.5 years = 18 months.
- Term unit — Years / Months
- Rate — % yearly
- Payment type — Annuity / Differentiated
- Extra monthly payment — $
- One-time fee — $
How to use
- — Enter the principal and nominal annual interest rate. Do not substitute a lender’s APR for the interest rate.
- — Choose months or years. The term must equal a whole number of months between 1 and 1,200; 1.5 years means 18 months.
- — Choose the repayment method, then enter a fixed monthly extra payment and one-time fee if your scenario requires them.
- — Compare interest, extra cost and actual repayment term. The table shows the first 12 months and the final payment of a longer schedule.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- CFPB (US): educational distinction between interest rate and APR
- Limitation
- Estimate with a constant nominal rate and equal model months. The entered one-time fee is included; regulated APR, insurance and lender-specific contract costs are not determined.
FAQ
How does the one-time fee affect this loan estimate?
Only the fee you enter is included, once, in total repayment and extra cost. The loan schedule and interest do not change. Financing the fee would require a separate scenario; this calculator does not add it to principal automatically.
What does a shorter term from a monthly extra payment mean?
The base payment remains fixed and the extra amount repays principal faster. The calculator does not recast the loan to a lower recurring payment. The final actual payment is only the principal and interest still due.
Does this loan estimate calculate a lender’s APR?
No. It models a nominal interest rate and one supplied fee. Regulated APR or full cost of credit is not calculated. Check the lender’s disclosures and schedule for insurance, other products, actual payment dates and contract rules.