Loan Payment Calculator
Monthly payment, total interest, and total cost for any fixed loan.
Input sheet
DIY at your own risk. Calcora's calculators and guides are general estimates and information only — not professional, engineering, legal, or safety advice. Always verify local building codes and permit requirements, and hire a licensed pro for electrical, gas, plumbing, structural, or any work you're not fully comfortable doing yourself.
Before you sign for a car, a personal loan, or any fixed-rate debt, this tells you the exact monthly payment and the real lifetime cost — including how much of your money goes to the lender as interest.
How it works
Standard amortization: M = P·r·(1+r)ⁿ ÷ ((1+r)ⁿ − 1), where r is the monthly rate and n the number of months.
A fixed-rate loan is amortized: every payment is identical, but the split shifts. Early payments are mostly interest because the balance is large; later payments are mostly principal. This calculator computes the level payment that pays the loan to exactly zero on the final month.
Total interest is simply the sum of every payment minus the amount you borrowed. A longer term shrinks the monthly payment but enlarges total interest, because you owe a balance for more months — that trade-off is the single most important thing to weigh before signing.
Monthly payment = principal × monthly rate × (1 + monthly rate) raised to the number of months, divided by ((1 + monthly rate) raised to the number of months, minus 1). Monthly rate is the annual rate divided by 12; number of months is years times 12.
Worked examples
$20,000 borrowed at 7.5% APR over 5 years (60 payments). → $400.76 per month; $4,045.54 total interest; $24,045.54 paid in full.
The monthly rate is 0.625% (7.5% ÷ 12). Over 60 months the amortization formula sets the level payment at $400.76, and 60 × $400.76 minus the $20,000 principal leaves $4,045.54 of interest.
$10,000 at 6% APR over 3 years (36 payments). → $304.22 per month; $951.90 total interest; $10,951.90 paid.
A shorter term and lower rate keep interest under a thousand dollars even though the payment is larger than the 5-year loan above.
Tips & gotchas
- Compare loans by total cost, not by monthly payment. A lower payment often hides a longer term and far more interest paid overall.
- Even a fraction of a percent on the rate matters over a long term — always quote APR, not just the headline 'monthly payment' a dealer leads with.
- Making one extra payment a year, or rounding the payment up, attacks principal directly and can shave months off the loan.
- If you can refinance to a meaningfully lower rate later, recompute here first to confirm the interest savings beat any refinance fees.
FAQ
Does this include fees?
No — it covers principal and interest only. Origination fees or insurance are extra.
What is the difference between APR and interest rate here?
This calculator treats the rate you enter as the nominal annual rate and divides by 12 for the monthly rate. A true APR also folds in certain fees, so a quoted APR can be slightly higher than the bare interest rate.
Why is so much of my early payment interest?
Interest is charged on the outstanding balance, which is highest at the start. As the balance falls, the interest portion shrinks and more of each fixed payment goes to principal.
Can I use this for a mortgage?
The payment math is identical for any fixed-rate amortizing loan, so yes for principal and interest. A real mortgage payment also adds property tax, insurance, and sometimes PMI, which this does not include.
Does a bigger down payment change the payment?
Yes — borrow less and the principal drops, lowering both the monthly payment and total interest. Enter the amount you actually finance after the down payment.
Related calculators
Tip with Tax Calculator · Salary to Hourly Calculator · Simple Interest Calculator · Rule of 72 Calculator · Mortgage Calculator