Amortization Calculator
See your exact monthly payment, the total interest you'll pay, and a year-by-year breakdown. Defaults to the live 30-year mortgage rate — add extra payments to see how much you'd save.
At the current 30-year average of 6.7% (Q2 2026), a $300,000 loan costs about $1,936/mo — and roughly $396,900 in interest over 30 years.
6.7%
current US 30-year fixed mortgage average — Freddie Mac via FRED (Q2 2026)
$1,936
monthly principal + interest on a $300,000 loan at 6.7% over 30 years (Q2 2026)
132%
of the amount borrowed is paid again in interest over a 30-year term at today's rate
What an amortization schedule really shows
The same monthly payment hides a shifting split between interest and principal.
Early payments are almost all interest
On a new loan, interest is charged on the full balance, so the first years' payments barely dent the principal. The balance curve starts shallow and steepens over time. This is why selling or refinancing early means you've built little equity — and why extra principal payments early have the biggest impact.
The true cost of borrowing
Interest is the price of time. On a $300,000 loan at 6.7% over 30 years you repay about $696,900 in total — roughly $396,900 of it pure interest. A shorter term has a higher monthly payment but dramatically less lifetime interest.
Extra payments beat the bank's math
Every extra dollar of principal erases all the future interest that dollar would have accrued for the rest of the term. That's why even modest extra payments — applied consistently — can shave years off the loan and save a large share of total interest, without refinancing.
How the Amortization Calculator Works
Formula
Monthly Rate (r) = Annual Rate ÷ 12
Number of Payments (n) = Term in Years × 12
Monthly Payment (M) = P × r ÷ (1 − (1 + r)^−n)
(when r = 0, M = P ÷ n)
Each month:
Interest = Remaining Balance × r
Principal = Payment − Interest
Balance = Balance − Principal
Total Interest = (Payment × n) − PrincipalEnter the loan amount
The principal you're borrowing — price minus any down payment.
Set the interest rate
Defaults to the live US 30-year fixed average (6.7%, Q2 2026); override with your actual APR.
Choose the term
How many years to repay — 15, 20, and 30 are most common.
Add an optional extra payment
Any amount above the scheduled payment goes straight to principal.
See payment, interest, and schedule
Your monthly payment, lifetime interest, balance curve, and payoff savings.
The key insight of amortization is that a fixed payment hides a moving target: early payments are mostly interest, and only later do they shift toward principal. That's why building equity feels slow at first and why extra principal payments early in the loan are so powerful.
Total interest depends heavily on the rate and term. Halving the term roughly raises the monthly payment but cuts lifetime interest dramatically — and any extra monthly payment erases the future interest on the principal it pays down.
Frequently Asked Questions
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