Mortgage Calculator

A mortgage calculator estimates the payments on a fixed-rate home loan and separates loan repayment from entered housing expenses. It can also show how additional principal changes payoff and how two terms or rates compare.

This tool models a fully amortizing loan with monthly payments. It does not model variable rates, interest-only periods, balloon agreements, lender eligibility or a binding offer. All starting prices and rates are examples for calculation, rather than current market quotes.

1. Enter the home purchase price and a down payment as a percentage or currency amount.
2. Enter the fixed contractual nominal annual interest rate. Choose a term preset or a custom number of months.
3. Optionally include property tax, homeowners insurance, mortgage insurance, HOA and other recurring costs.
4. Add extra principal if you want to explore early payoff. Set annual and one-time payments by their payment numbers.
5. Enter a first scheduled payment date when calendar dates are useful. Otherwise the schedule uses payment numbers.
6. Review the housing budget, loan totals, balance chart and yearly amortization. Expand a loan year for monthly rows, then copy, print or export the selected schedule.

Calculations run locally and update while you edit. Currency changes formatting only. Reset restores the 400,000 home-price, 20%-down, 6%-rate, 30-year example and clears optional assumptions.

For a purchase price of 400,000 and a 20% down payment, the down payment is 80,000 and the financed principal is 320,000. At an illustrative fixed nominal annual rate of 6%, the monthly decimal rate is 0.06 ÷ 12 = 0.005. A 30-year term has 360 monthly periods.

The unrounded payment is approximately 1,918.561680, giving a regular monthly P&I payment of 1,918.56. If annual property tax is 4,800, annual homeowners insurance is 1,200 and HOA fees are 100 a month, the housing budget is 1,918.56 + 400 + 100 + 100 = 2,518.56 per month, before any extra principal.

M = P × r × (1 + r)ⁿ / [(1 + r)ⁿ − 1], equivalently M = P × r / [1 − (1 + r)^(−n)].

P is the initial loan principal, r is the monthly decimal interest rate and n is the number of monthly payments. Convert an annual percentage using r = annual percentage ÷ 1200. The formula is evaluated with a stable logarithmic form to retain precision at very small rates.

At zero interest, the expression’s interest-rate form is replaced by M = P ÷ n. The payment and monthly interest are rounded to cents, and the last payment is adjusted to clear the balance.

Principal is the outstanding borrowed amount; interest is the charge for borrowing it. Scheduled principal is the portion of that month’s P&I payment remaining after interest. Only principal payments reduce the loan balance.

The initial 320,000 balance at a monthly rate of 0.005 accrues 1,600 interest in its first period. From a 1,918.56 scheduled payment, 318.56 goes toward principal before any extra payment. Later rows use the reduced starting balance. See the CFPB explanation of mortgage amortization.

A down payment is the part of the purchase price you fund without the modeled loan. Here, loan amount = purchase price − down payment. Zero down finances the full entered price; a full down payment makes the purchase cash funded.

Amount and percentage entry views share the same calculation. Changing the view retains the current down payment. A percentage entered by the user scales with subsequent purchase-price changes, while a currency amount stays fixed until edited.

At the same rate and term, a larger down payment reduces the financed principal and therefore the formula payment. It also changes the initial loan-to-value ratio.

LTV = initial loan ÷ reference property value × 100. The 320,000 loan against a 400,000 purchase price has an initial LTV of 80%. You can supply another property reference value, but the numerator remains the initial loan. No appreciation, appraisal result or insurance eligibility is forecast.

PITI groups principal, interest, property taxes and homeowners insurance. The calculator also lists entered mortgage insurance, HOA and other recurring costs to build a broader housing budget.

A housing budget can include expenses paid outside the lender’s statement. The total shown here does not imply that the lender collects all of those amounts. The CFPB distinguishes principal and interest from the full monthly payment.

Enter annual amounts, not a percentage of the property price. The calculator divides each by 12 and rounds it to a monthly budget amount. Repeated rounded monthly budgets can differ by a few cents from an annual bill.

These inputs stay constant over the original selected term. The model does not forecast tax reassessments, policy changes, maintenance, repairs or inflation. Such expenses can continue after a mortgage is paid off, so an early payoff does not erase them from the planning horizon.

Mortgage insurance can protect a lender against specified borrower default losses. Private mortgage insurance, or PMI, is one form used with some mortgages; it is different from homeowners insurance. Requirements depend on the country, loan program and contract.

Enter a monthly premium or an annual percentage of the initial loan. That entered cost is modeled as a constant monthly amount until loan payoff. The calculator does not decide whether insurance is required or automatically end it at an LTV threshold. The CFPB’s PMI explanation provides context for US conventional loans.

The schedule records each payment period’s starting balance, interest, scheduled principal, extra principal and ending balance. Payment dates are optional. When entered, they are anchored to the first payment’s day each month and constrained to the destination month’s final valid day.

Yearly summaries group payments 1–12 into loan year one, 13–24 into year two, and so on. Choose a loan year to view its monthly rows. The annual principal column already includes extra principal; total payments already include both scheduled payments and extras.

Print and CSV include the full selected monthly schedule. The final scheduled payment can differ from the regular payment because it clears all remaining principal and that month’s interest.

Extra Principal Payments lets you model a recurring monthly amount, an annual amount and one one-time payment. Annual extras begin at a selected payment number from 1 to 12 and repeat every 12 payments. A one-time extra applies at the selected payment number only if a balance remains.

All extras follow that period’s scheduled P&I payment. They are applied to principal and capped at the remaining balance. The standard-vs-extra comparison recomputes the payoff and interest using identical rounding rules. Confirm how your lender processes additional principal and whether a prepayment charge applies.

Interest in the next period uses the balance left after the current scheduled and extra principal payments. Reducing that balance earlier can reduce future interest. At a zero interest rate, extra principal can shorten payoff without creating interest savings.

For the 320,000, 6%, 30-year example, enter an additional 200 monthly to calculate the resulting payoff and savings. Those results come from the generated schedule and update with your assumptions. The chart compares standard balances with balances after extra principal over the same timeline.

For the same principal and positive rate, repaying over fewer months generally increases the monthly payment and lowers the total interest. A longer term spreads repayment over more periods.

The optional offer comparison starts with 180 and 360 months and allows a separate rate for each. Enter actual offers rather than assuming one term has a lower rate. This table compares loan P&I and interest only; fees, closing costs, housing expenses and extra payments are excluded.

In exact mathematical amortization without rounding, total interest = unrounded monthly payment × number of payments − principal. For 320,000 at 6% over 360 months, that formula estimate is approximately 370,682.20.

The calculator separately adds actual cent-rounded monthly interest for its scheduled-interest total. Rounding the regular payment to cents and correcting the final payment creates a small difference from the unrounded formula estimate. Cards, yearly totals, chart balances and exports use the same cent-based schedule.

Total P&I is not the entire cost of owning a home. The modeled housing outlay adds the down payment, selected loan payments and entered recurring costs over the original term. It does not add the purchase price or borrowed principal again, and it excludes closing costs and unentered expenses.

This mortgage tool focuses on a purchase price, down payment, housing costs and property reference values. The general Loan Calculator covers fixed-rate borrowing with its own fee and APR-estimate features.

Use the contractual nominal interest rate for mortgage amortization. APR is a broader cost measure that can include fees and other charges; substituting it for the contract rate can change the payment estimate. See the CFPB explanation of interest rate and APR.

Fixed nominal annual rate divided by 12; payments at monthly period end. Payment formula rounded to cents; monthly interest rounded half up using exact rate scaling. Final payment clears the balance. Extra principal follows the scheduled payment, capped at the remaining principal. Dates are labels, not daily-interest accrual. Annual recurring costs are divided by 12 and rounded to a monthly budget amount. All other entered housing costs stay constant. Mortgage insurance remains flat until loan payoff; no eligibility or LTV cancellation is inferred.

Money inputs allow two decimal places, rates six, and down-payment percentages twelve. Individual amounts are limited to 10 billion currency units. Durations are whole months from 1 to 600. Dates use the Gregorian calendar with years 0001–9999 and must accommodate the selected payoff timeline. No first payment date is assumed from today.

Calculations estimate payments only. They do not determine lender approval, affordability, eligibility, actual APR or legal lending terms. Schedules can differ from a lender’s because of day-count methods, payment dates, fees, interest rounding or processing rules.

• CFPB: principal and interest versus total monthly payment
• CFPB: how paying down a mortgage works
• CFPB: mortgage interest rate and APR
• CFPB: private mortgage insurance