Mortgage Overpay Calculator

Take control of your mortgage and your future. 

Mortgage Overpayment Calculator shows you exactly how much time and interest you can save by making one‑off or recurring overpayments, then lets you compare that strategy to investing or saving the money instead. 

It’s fast, accurate, and designed to look amazing.

Enter your mortgage details in seconds: debt, term (years and months), mortgage type (repayment or interest‑only), and either your interest rate or your monthly payment.

Add overpayments as a fixed amount or a percentage, with flexible schedules (daily, bi‑weekly, monthly, bi‑monthly, bi‑annually, or annually). 

Turn on “Compare to Savings” to project what you might earn at your chosen savings rate with your own tax rate. 

Then explore crystal‑clear tables and charts that reveal your debt over time, months/years saved, interest saved, and your net benefit.

Save your scenarios, revisit them any time, and edit them as your finances change. It’s your mortgage—made understandable.

Key Features

• Flexible term input: Enter years and months for precise results. • Repayment & interest‑only: Accurate models for both, including overpayment effects on principal. • Smart overpayments: One‑off and recurring, as currency or %, with multiple frequencies. • Savings comparison: Compare overpaying vs investing with custom interest and tax rates. • Beautiful charts & tables: See your debt from Month 0 to payoff. • Precision financials: Two‑decimal accuracy with correct payoff handling to £/$0.00. • Save & edit: Keep multiple scenarios, overwrite or save as new - your choice! • Modern UX: Clean, delightful SwiftUI design with your local currency symbol.

Why You’ll Love It

• Clarity: Instantly see how small changes save big money and time. • Confidence: Make smarter decisions - overpay, invest, or both. • Control: Build and compare multiple strategies as your life evolves.

How It Works

• Enter mortgage debt, term, and type • Input interest rate or monthly payment (auto‑calculation fills the other) • Add overpayments (one‑off and/or recurring) as £/$ or % • Optionally compare to savings with your rate and tax • Tap calculate to see time saved, interest saved, remaining debt, and charts • Save your scenario for later and update anytime

Ideal For • Homeowners planning to overpay • First‑time buyers comparing options • Anyone deciding between overpaying vs investing

This is a guide only, not financial advice. Consult a professional for personalized recommendations.