# UK Mortgage Calculator

> Work out monthly UK mortgage payments on a repayment or interest-only basis from the price, deposit, rate and term, with LTV and a rate-rise stress test.

Category: Finance · Applies to: GB · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/mortgage-calculator-uk

Enter the property price, your deposit, the rate and the term. A repayment mortgage clears the loan by the end; an interest-only mortgage costs less each month but leaves the whole loan to repay at the end.

Also called: Mortgage repayment calculator (UK).

## Inputs
- Property price (default 300000)
- Deposit (default 30000)
- Interest rate (per year) (unit %; default 4.5)
- Mortgage term (unit years; default 25)
- Mortgage type (options: Repayment, Interest-only; default repayment)
- Rate rise to test (unit percentage points; default 3; optional)
- Currency

## Results
- Monthly payment
- Mortgage amount
- Loan-to-value (LTV)
- Monthly payment if the rate rises
- Total interest over the term
- Total repaid

## Formula

```
Repayment: M = L × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1);  Interest-only: M = L × r;  LTV = L ÷ Price
```

Where:
- L: loan = price − deposit
- r: annual rate ÷ 12 ÷ 100
- n: term in months

## Worked example
1. Loan = £300,000 − £30,000 = £270,000, an LTV of 90%.
2. r = 4.5 ÷ 12 ÷ 100 = 0.00375 and n = 300; M = 270,000 × 0.00375 × 1.00375³⁰⁰ ÷ (1.00375³⁰⁰ − 1) = £1,500.75.
3. At 7.5% (a 3-point rise) the same loan costs £1,995.28 a month.

**Result:** A £270,000 repayment mortgage at 4.5% over 25 years costs about £1,501 a month, rising to about £1,995 if rates went up by 3 points.

## What the result means

Lower LTV bands generally get better rates, so a slightly bigger deposit can cut the cost twice. Most UK deals are fixed for 2–5 years and then revert to a variable rate, which the stress-test figure helps you plan for.

## Assumptions and limits
- The rate stays the same for the whole term (in practice it changes when a fixed deal ends).
- Interest is charged monthly at the annual rate ÷ 12.
- Stamp Duty Land Tax, arrangement fees, valuation and legal costs are not included.
- Lenders’ affordability checks are not modelled.

## Questions

### What is LTV?

Loan-to-value: the mortgage as a percentage of the property price. A £30,000 deposit on £300,000 means a 90% LTV.

### Repayment or interest-only?

Repayment clears the debt by the end of the term. Interest-only is cheaper monthly, but you must repay the full loan at the end from another source, and lenders require a credible plan for that.

## Related calculators
- [Mortgage Calculator](https://calculators.geekmidst.com/calculators/mortgage-calculator)
- [Mortgage Amortization Calculator](https://calculators.geekmidst.com/calculators/mortgage-amortization-calculator)
- [Down Payment Calculator](https://calculators.geekmidst.com/calculators/down-payment-calculator)

_This calculator gives estimates for planning. It is not financial advice, and lenders’ actual terms, fees and rounding may differ._

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/mortgage-calculator-uk