Monthly payments, total interest, amortization schedule — calculated instantly for any loan.
Your monthly mortgage payment is calculated using the standard amortization formula: M = P[r(1+r)ⁿ]/[(1+r)ⁿ−1], where P is principal, r is the monthly interest rate, and n is the number of payments.
In the early years of a loan, the majority of each payment goes toward interest. As the principal decreases, more of each payment shifts to reducing the actual loan balance.
This is why making extra principal payments early in the loan term has such a dramatic effect on total interest paid.
A fixed-rate mortgage locks your interest rate for the life of the loan, giving you predictable payments. It's ideal when rates are low or you plan to stay long-term.
An adjustable-rate mortgage (ARM) starts with a lower fixed rate, then adjusts periodically based on market indexes. A 5/1 ARM is fixed for 5 years, then adjusts annually.
ARMs can save money if you sell or refinance before the adjustment period, but carry risk if rates rise significantly.
This calculator shows your principal and interest (P&I) payment. Your actual monthly payment will also include escrow costs for property taxes, homeowner's insurance, and potentially PMI (private mortgage insurance) if your down payment is under 20%.
PMI typically costs 0.5–1.5% of the loan annually and is automatically removed once you reach 20% equity.
Making bi-weekly payments instead of monthly effectively adds one extra payment per year, which can reduce a 30-year mortgage by 4–6 years.
Applying any windfalls (tax refunds, bonuses) directly to principal has an outsized effect early in the loan when interest charges are highest.
Refinancing when rates drop by 0.75% or more can also significantly reduce your total cost, especially if you have 10+ years remaining on the loan.
This calculator uses the standard amortization formula that virtually every bank, credit union, and mortgage servicer uses to set fixed monthly payments: M = P × r(1+r)n / ((1+r)n − 1), where P is the amount borrowed, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. Nothing is estimated or approximated — the same inputs will match a lender's quote to the penny, before taxes, insurance, and fees are added.
Borrow $280,000 for 30 years at 6.4%. The monthly rate is 0.533%, n is 360 payments, and the formula gives a payment of $1,751.42. Over the full term you would pay about $630,510 in total — $280,000 of principal and roughly $350,510 of interest, more than the original loan itself.
The first payment shows why payoff feels slow early on: $1,493.33 of that first $1,751.42 is interest and only $258.08 reduces the balance. The split improves every month as the balance falls — that shifting split is exactly what an amortization schedule tracks, and it is why the same loan feels very different in year 2 versus year 22.
Add $200 a month to the example above and the loan pays off in about 273 months (22.8 years) instead of 360, cutting total interest by roughly $99,000. Extra principal early in the loan is worth far more than the same dollars late, because every prepaid dollar stops compounding interest for the entire remaining term.
Comparing a lender's interest rate against another lender's APR — APR folds certain fees into the rate, so it is always the higher, more complete number; compare like with like. Ignoring escrow: your real housing payment adds property taxes and insurance on top of the principal-and-interest figure this calculator produces. And judging affordability by the payment alone: a longer term always lowers the payment but raises total interest — the two numbers must be read together.
Does this calculator work for car loans and personal loans?
Yes. Any fixed-rate, fully amortized loan — mortgages, auto loans, personal loans, most student loans — follows the same formula. Enter the amount, rate, and term in years.
Why is my lender's payment slightly different?
Lenders quote principal and interest with the same formula, but your bill may add escrow for taxes and insurance, or mortgage insurance. Rounding conventions can also shift the payment by a few cents.
Is it better to take a shorter term?
A 15-year term roughly doubles the pace of principal payoff and typically carries a lower rate, but the required payment is much higher. Many borrowers keep a 30-year term for flexibility and prepay when they can — the extra-payment example above shows the effect.
Last updated: August 8, 2026 · Reviewed by the DollarDrill editorial team. Formulas follow standard published methods; see our editorial standards & sources. Results are educational estimates, not financial advice.