Loan Calculator
Monthly payment, total interest and payoff cost.
A loan calculator uses the amortization formula to split each payment between interest and principal.
The numbers above are estimates for comparison. Before borrowing, make sure you understand APR, origination fees, and how the loan term changes your total cost.
How to use
- Enter the loan amount, annual interest rate and term in years.
- Click Calculate for the monthly payment breakdown.
- Try a shorter term to see how much interest you save.
About this tool
Early payments go mostly to interest; later payments pay down principal faster — which is why extra payments early save the most.
These are estimates only. Lenders add fees, insurance and their own APR calculations on top.
How it works
A fixed-rate loan uses the amortization formula: monthly payment = P x R / (1 - (1 + R)^-N), where P is the loan amount, R the monthly interest rate (annual rate / 12), and N the total number of payments. Each payment is split between interest and principal, with the interest portion shrinking every month as the balance falls.
That shifting split is why early extra payments save so much: money paid toward principal in year one avoids interest compounding for the entire remaining term. A zero-interest loan is the simple case — just P / N per month.
Worked examples
$200,000 mortgage at 6.5% for 30 years: R = 0.065 / 12 = 0.005417, N = 360. Payment = 200000 x 0.005417 / (1 - 1.005417^-360) = $1,264.14 per month. Total paid: $455,090 — of which $255,090 is interest, more than the loan itself.
Quick reference
| Rate (30-yr) | Monthly per $100k | Total interest per $100k |
|---|---|---|
| 5.0% | $536.82 | $93,255 |
| 6.0% | $599.55 | $115,838 |
| 7.0% | $665.30 | $139,508 |
| 8.0% | $733.76 | $164,154 |
Frequently asked questions
How is the monthly payment calculated?
With the amortization formula: M = P·r/(1−(1+r)^−n), where r is the monthly rate and n the number of payments.
What is the difference between interest rate and APR?
The interest rate is the cost of borrowing; APR includes fees and is usually slightly higher — it is the better number for comparing loans.
Is this financial advice?
No — these are rough estimates for planning. Talk to a licensed professional before signing anything.
More free tools
Percentage Calculator
Work out percentages, increases and discounts in one click.
Age Calculator
Find your exact age in years, months and days.
BMI Calculator
Check your Body Mass Index in seconds.
Tip Calculator
Split the bill and work out the tip in seconds.
Discount Calculator
See the sale price and how much you save, instantly.
Unit Converter
Convert length, weight and temperature instantly.