🇬🇧 UK Mortgage Repayment Calculator

Monthly payment, total interest over the term, and the balance at the end of any fixed-rate period — using UK convention (monthly-paid-in-arrears).

🇬🇧 UK Mortgage Repayment Calculator — Monthly payment, total interest, and balance at the end of any fixed-rate period. Uses UK convention (monthly-paid-in-arrears).

Enter Your Mortgage Details

Mortgage Balance (£)

Interest Rate (%, annual)

Term (years)

Fixed-Rate Period (years) optional — leave 0 for none

Results

Monthly Payment

—

Capital + interest, paid in arrears

Total Interest Over Term

—

Across all years at this rate

Total Paid Over Term

—

Capital + total interest

Balance at End of Fixed Period

—

The amount you'll be remortgaging

Year-end balance snapshots

Year	Year-end balance	Interest this year	Capital this year

Methodology & Sources

Standard UK amortisation formula: M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1), where P is the balance, r is the monthly rate (annual ÷ 12), and n is total months (years × 12). UK lenders charge monthly in arrears — payment at month-end. The fixed-period balance is what you'll be remortgaging when your initial fix ends and the loan reverts to the lender's Standard Variable Rate (SVR), which is typically 1–4 percentage points higher.

FCA mortgage rules: Financial Conduct Authority — Mortgages
Stamp Duty Land Tax (separate calc): GOV.UK — SDLT
Bank of England base rate: BoE — Bank Rate (drives variable-rate mortgages)

Last verified: May 2026.

Frequently Asked Questions

How is a UK mortgage repayment calculated?

UK mortgages use the standard amortisation formula: M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1), where P is the loan amount, r is the monthly interest rate (annual ÷ 12), and n is the total number of monthly payments. The same payment is made every month, but the split between interest and capital shifts over time — early payments are mostly interest, later ones mostly capital.

UK vs US mortgage — what's the difference?

Maths is identical (same amortisation formula). What differs is the rate environment: UK borrowers typically take a 2/3/5/10-year fixed-rate deal then revert to the lender's Standard Variable Rate (SVR) — a step-up that doesn't exist in the US 30-year-fixed market. UK mortgages also charge in arrears (end of month), US in advance (start of month). Both differences are sub-percent annual cost — the headline rate matters far more than the convention.

What happens when my fixed-rate period ends?

Your mortgage reverts to your lender's Standard Variable Rate (SVR) — typically 6–9% in 2026, well above current fixed-rate deals. Two options: (1) Remortgage to a new fixed-rate deal with the same or a different lender (usual choice, costs £500–£1,500 in fees) or (2) Stay on SVR temporarily if you're planning to sell or repay imminently. Most borrowers start shopping for a new fix 6 months before fix-end.

How does APRC differ from interest rate?

APRC (Annual Percentage Rate of Charge) is the all-in cost of the mortgage including arrangement fees, valuation fees, and any other charges, expressed as an annual rate. The headline interest rate is just the rate on the borrowing itself. Two products at the same headline rate can have meaningfully different APRC. For comparison shopping, the APRC is the honest number; for budgeting your monthly payment, use the headline rate.

What affects what I can borrow?

UK lenders cap mortgages at typically 4.5× joint income, with stress-tests at a higher rate (usually fix rate + 1% or SVR + 1%, whichever is greater). Deposit size matters: 5–10% deposit gets you a high-LTV product at higher rate; 20–25% deposit unlocks materially cheaper deals. Credit history, employment type (self-employed faces more scrutiny), affordability of other debt, and the property type (flats above commercial, ex-local-authority, non-standard construction) all affect approval and rate.

What is an interest-only mortgage?

An interest-only mortgage pays ONLY the monthly interest — the principal balance stays the same for the whole term. You're expected to repay the principal at term-end via an investment vehicle (ISA, pension) or property sale. Cheaper monthly than repayment, but you owe the full balance at the end. Now mostly restricted to buy-to-let mortgages or high-net-worth residential borrowers with proven repayment vehicles. This calculator models REPAYMENT (capital + interest) mortgages.

What's the difference between repayment and overpayment?

A repayment mortgage pays off both interest and capital each month over the agreed term. An overpayment is an additional payment on top of the scheduled monthly payment that goes 100% against the capital. Most UK fixed-rate mortgages allow up to 10% of the outstanding balance per year in overpayments without an Early Repayment Charge — beyond that, lenders charge a percentage of the excess. Use the Mortgage Overpayment Calculator to model the impact.

Should I take a 2, 5, or 10-year fix?

Trade-off between rate certainty and rate exposure. 2-year fixes typically have lower headline rates and more product choice but expose you to remortgage risk every 2 years (and ~£1k in fees each time). 5-year fixes give 60 months of certainty at a small premium. 10-year fixes cost more upfront but if rates rise materially you've locked in cheap money for a decade. Most UK borrowers (around 60%) take a 5-year fix as the middle-ground default.

Can I switch lenders mid-fix?

Yes, but with an Early Repayment Charge (ERC) — typically 1–5% of outstanding balance, decreasing as the fix nears end. For a £200k mortgage at 3% ERC, that's £6,000 — usually more than the savings from switching, unless rates have dropped substantially or your circumstances have changed. ERC is the reason most borrowers wait for fix-end before remortgaging.

How to use this calculator

Takes about 2 minutes.

Enter your mortgage balance in pounds
Set your interest rate (annual %)
Enter the total term in years
Optionally enter the fixed-rate period (2, 5, or 10 years)
Review monthly payment, total interest, and balance at fixed-end

Try these scenarios

Tap a scenario to load it into the calculator above.

Key concepts

The amortisation formula. Every UK mortgage uses the same standard formula: M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1). Same payment every month but the interest/capital split shifts — early years are mostly interest, later years mostly capital. The first year of a 25-year £200k mortgage at 5% pays ~£10k interest and ~£4k capital; the last year pays the inverse.

The fixed-rate cliff. UK mortgages typically come with a 2-, 5-, or 10-year fixed rate, then revert to the lender's Standard Variable Rate (SVR) — which in 2026 is 6–9%, well above current fixed deals. The fixed-rate-end balance is what you'll be remortgaging. If you don't remortgage on time, you'll be paying the SVR — which on a £150k balance at SVR 7% vs a 5% remortgage is around £150/month wasted.

APRC vs headline rate. APRC is the lender's all-in cost including arrangement fees, valuation fees, and other charges, expressed as an annual rate. The headline rate is the borrowing rate only. APRC is the honest comparison number; the headline rate determines your monthly payment.

Affordability stress-tests. UK lenders test your ability to pay at SVR + 1% (or 6.99% minimum) — meaning your true borrowing capacity is roughly 4.5× joint income at TODAY's rates, not at the rate of a cheap 2-year fix. This is why borrowers get materially smaller offers in high-rate environments.

Common UK borrower mistake. Letting your fix expire onto SVR without remortgaging. The fee for remortgaging is £500–£1,500; the SVR penalty is often £100–£300/month — i.e. the fee pays for itself in 3–6 months. Set a calendar reminder for 6 months before fix-end and shop around.

Written and maintained by James Blanckenberg, Founder & Editor, FinCalcHub.

Last reviewed: 17 May 2026 · See editorial policy