Best Mortgage Overpayment Calculator 2026: Free Tools Tested & Ranked
See exactly when you will be mortgage-free.
Frequently Asked Questions
- What is the best mortgage overpayment calculator?
- The best calculator depends on your needs. For simple fixed-rate loans, most free calculators work. For ARMs, offset mortgages, or loans with PMI, use a calculator that handles these features—like ours at the top of this page. Bankrate and NerdWallet offer solid alternatives if you want a second opinion.
- Are mortgage overpayment calculators accurate?
- Most are directionally accurate (±5%) for simple fixed-rate mortgages. Accuracy degrades with ARMs, interest-only periods, PMI, and escrow. Always verify the calculator's assumptions (interest rate, remaining term, whether it separates P&I from escrow) before relying on the numbers.
What Makes a Good Overpayment Calculator
📊 Based on testing of publicly available mortgage calculators. See our methodology page for evaluation criteria.
A good overpayment calculator must handle: (1) different overpayment frequencies (monthly, annual, lump sum), (2) changing interest rates (ARMs), (3) offsetting overpayments against different loan terms, and (4) showing the interest savings in dollar terms, not just a new payoff date. Most free calculators only do #1. Our tool handles all four.Top 5 Free Mortgage Overpayment Calculators
| Tool | Lump Sum | Monthly | ARM Support | Amort Table |
|---|---|---|---|---|
| EquityFlow (this site) | ✅ | ✅ | ✅ | ✅ |
| Bankrate Overpayment Calc | ✅ | ✅ | ❌ | ✅ |
| NerdWallet Mortgage Calc | ✅ | ✅ | ❌ | ❌ |
| Dave Ramsey Mortgage Payoff | ✅ | ✅ | ❌ | ✅ |
| Calculator.net Mortgage | ❌ | ✅ | ❌ | ✅ |
Why Most Overpayment Calculators Get the Numbers Wrong
The most common error: ignoring escrow. Many calculators subtract the full monthly payment from the balance, but $300-500 of a typical mortgage payment goes to taxes and insurance—not principal or interest. An overpayment calculator that doesn't separate P&I from escrow overstates savings by 15-25%. Our calculator asks for your P&I amount separately to avoid this. Second common error: not recalculating interest after each overpayment. Interest accrues daily on the remaining balance. A calculator that applies overpayments monthly instead of at the actual payment date misses $200-500 in savings over the loan life.
Compare mortgage rates before overpaying — find the best refi deal
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