Calcs4All

APR 23 · 2026

Mortgage calculator

Estimate monthly mortgage payments with deterministic rounding.

What this calculator covers

Estimate a mortgage payment from principal, rate, and term with consistent rounding.

The explanation keeps the payment math visible so the result can be checked before it is trusted.

Frequently asked questions

What does this mortgage calculator include in the monthly payment?
This tool calculates principal and interest only on a fixed-rate loan. It does not add property taxes, homeowners insurance, PMI, or HOA dues — add those separately if you want the full monthly housing cost.
What formula does it use?
The standard amortization formula for a fixed-rate loan: M = P × (r(1+r)^n) / ((1+r)^n − 1), where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the number of monthly payments.
How accurate is the monthly payment estimate?
The math is exact for a given rate and term, rounded to the nearest cent. Lenders may compute to a slightly different rounding policy or include origination fees in the APR, so use this as a baseline and compare against a lender's loan estimate for the final figure.
Can I use this for an adjustable-rate mortgage?
Not directly. This tool assumes a single fixed rate for the life of the loan. For an ARM, estimate the initial fixed-rate period separately and plan for possible rate changes at each adjustment.

Tool

Run the calculation

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yr

RESULT · MORTGAGE

â„–002

Primary result

$1,798.65

A $300,000.00 loan at 6% over 30 years has a monthly payment of $1,798.65.

Monthly payment
$1,798.65
Total payment
$647,514.00
Total interest
$347,514.00

Step-by-step solution

  1. 1.Convert the annual rate to a monthly rate: 0.005.
  2. 2.Spread the loan across 360 monthly payments.
  3. 3.Round the monthly payment to 2 decimals for display: $1,798.65.

Walkthrough

Visual walkthrough

Break the mortgage payment into the rate conversion, payment count, and amortized payment result.

  1. 01

    Set the monthly rate

    6% ÷ 12 = 0.005

    Amortization works on the periodic rate, so the annual rate must be converted to a monthly rate first.

    Monthly rate 0.005

  2. 02

    Count every payment

    30 × 12 = 360

    A fully amortizing mortgage spreads principal and interest over the full number of monthly payments.

    360 monthly payments

  3. 03

    Read the payment and lifetime cost

    The amortization formula produces the fixed monthly payment, then the total payment and interest follow from that monthly figure.

    Monthly payment $1,798.65