How to Calculate a Mortgage Payment
How to calculate a monthly mortgage payment by hand, including the formula, a worked example, and what's not included.
Reviewed Jan 15, 2025
Quick answer
Monthly payment = P × r × (1 + r)^n ÷ [(1 + r)^n − 1], where P is loan amount, r is the monthly rate, and n is total months. The formula gives principal and interest only — taxes and insurance add on top.
Try it
Open full calculatorMortgage Calculator
Estimate your monthly mortgage payment, total interest, and amortization.
Result
Principal & interest of $2,023/mo on a $320,000 loan over 30 years at 6.5%.
- Loan amount
- $320,000
- Principal & interest
- $2,023
- Tax + insurance
- $525
- Total interest paid
- $408,142
- Total of payments
- $728,142
- Term
- 30 years
Inputs
Try an example
How it works
Each payment covers interest first; what's left chips away at principal. Early in the loan most of your payment is interest.
Formula
M = P · r(1+r)ⁿ ÷ ((1+r)ⁿ − 1)
Common mistakes
- Forgetting taxes, insurance, and HOA — they often add 15–25%.
- Comparing only monthly payments instead of total interest.
Related calculators
Last updated
Reviewed Apr 15, 2026.
Calcxo gives you the answer plus the reasoning behind it.
What the formula gives you
The standard mortgage formula returns the principal and interest portion of your payment. Property taxes, homeowners insurance, mortgage insurance, and HOA dues are real costs that aren't in this number.
$300,000 at 6.5% for 30 years
A concrete walkthrough you can follow line by line.
P = 300,000; annual rate = 6.5%; term = 30 years.
1. Monthly rate
0.065 ÷ 12 ≈ 0.005417
2. Total months
30 × 12 = 360
3. Apply formula
≈ $1,896 per month in P&I
Result
About $1,896/month before taxes and insurance.