Refinance Mortgage Payment Calculator

📖 Overview

Use this tool to compare potential refinance monthly payment outcomes before applying.

Use these default and higher-pressure example inputs to explore how sensitive this calculator is before using your real numbers.

Input	Base Case	Higher Pressure Case
Loan Amount ($)	450,000	517,500
Annual Interest Rate (%)	6.25	7.5

This formula uses a standard fixed-rate amortization model over 360 months to estimate a stable monthly payment.

The Formula

M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]

M	Monthly payment
P	Principal loan amount
r	Monthly interest rate = Annual rate ÷ 12 ÷ 100
n	Total number of payments = 360 for a 30-year loan

💡A 1% rate difference on a $400,000 loan changes your monthly payment by ~$235 and total interest paid over 30 years by ~$84,000.

Rate	$300k Loan / mo	$400k Loan / mo	$500k Loan / mo
5.0%	$1,610	$2,147	$2,684
6.0%	$1,799	$2,398	$2,998
6.5%	$1,896	$2,528	$3,160
7.0%	$1,996	$2,661	$3,327
7.5%	$2,097	$2,796	$3,495

Use this tool when you need a fast decision during active planning or execution.
Use this before committing money, time, or tradeoffs that are hard to reverse.
Use this to compare options using the same assumptions across scenarios.

Results can be misleading if key inputs are missing, stale, or unrealistic.
Very small or very large values may amplify rounding effects and interpretation risk.
If assumptions change mid-decision, recalculate before acting.

💡 Run multiple rate scenarios before locking a mortgage.

💡 Keep total housing cost, not only principal and interest, in your budget.

💡 Use a conservative income assumption if your earnings vary.

❓ Does this include taxes and insurance?

No. This estimate focuses on principal and interest only.

❓ Why does a small rate change matter?

On long terms like 30 years, rate shifts compound into large payment differences.