Mortgage Calculator
Works out your mortgage payment and shows what lies behind that number: how much goes to principal, how much to interest, how that changes from one payment to the next, and what would happen with a different rate or term. Everything on the device, even without a connection.
Free, for iPhone
The Calculate tab
Four inputs and that’s it: amount, start date, annual rate and term, the last two set with a slider. The payment is recalculated instantly with every change, along with the total repaid and the total interest. The bar at the bottom shows at a glance how principal and interest split over the whole term.
The calculation uses the French method with a constant payment, the one behind almost every mortgage: the payment stays the same for the whole term, and what changes is its internal make-up.
The schedule, payment by payment
The Amort. schedule tab gives the full detail: the number and due date of each payment, the principal and interest portions with a bar showing how they compare, and the outstanding principal after the payment. As you scroll down, the bar gradually turns green — the typical effect of French amortisation, where at the start you pay mostly interest and towards the end mostly principal.
The schedule exports in two formats: CSV to work on it in Numbers, Excel or Google Sheets — ISO dates and numbers with a decimal point, so the import works in any language — and a laid-out PDF, ready to print or send.
The Scenarios tab
It answers the “what if…” question. Two sliders change the rate and the term, and the new payment appears right away. The chart compares eight terms, from 5 to 40 years: for each one, a column split between principal — which never changes, it’s the sum you borrowed — and interest, which grows as the term gets longer. It’s the most direct way to see the basic trade-off in every mortgage: a longer term lowers the payment, but raises the total interest.
Which rate to enter
It’s the nominal annual rate, not the APR, which also includes ancillary costs. And if your bank quotes a different payment, it’s usually because theirs includes insurance, collection fees or taxes: the app calculates the pure payment of principal and interest. The last payment may differ by a few cents — that’s correct, it’s adjusted to bring the outstanding principal exactly to zero.
For a variable-rate mortgage you can simulate any rate, but the schedule keeps it fixed for the whole term: to understand the effect of a rate rise, the Scenarios tab is the right tool. And to know where the rate starts from today, Euribor X keeps the fixings up to date.
Free, and the ads can go
Mortgage Calculators is free and complete, supported by Google AdMob ads. You can decline both Google’s consent and Apple’s tracking: the ads stay but aren’t personalised, and the app works exactly the same. And the ads can be removed with an in-app purchase: an annual subscription, or a one-time purchase that lasts forever.
The old paid version is now called Mortgage Calculator Legacy: it keeps working but no longer gets updates. If you bought it, you can move to Mortgage Calculators without ads and without paying again — the support page explains how.
A word of caution
It’s a calculation and simulation tool, not financial advice. The results are indicative: for a real commitment, always refer to your lender’s documents.
- Platform
- iPhone · Mortgage Calculators
- Price
- Free with ads · removable with an annual subscription or a one-time purchase
- Method
- French amortisation with a constant payment · calculations on the device, offline too
- Export
- Full schedule in CSV and PDF
- App Store
- Open the app’s page
- Support
- User guide and FAQ
- Privacy
- Privacy policy