UK Mortgage Payment & Affordability Calculator (2026/27)
Calculate your monthly UK mortgage repayments, total interest, and overall loan cost under Bank of England and FCA affordability criteria. Models repayment (capital and interest) versus interest-only borrowing, LTV deposit tiers (5% to 25%), and stress tests your monthly budget against a +2% interest rate rise.
Mortgage Parameters
UK Residential Lending Rates & FCA Affordability Models (2026/27)
Calculation Breakdown
85.0% Loan-to-Value (LTV) on £350,000.00 purchase price
Interest charged by lender in month 1
Equity built toward paying off mortgage balance
25-year term at 4.50% fixed
Full capital repaid by end of term
Loan capital borrowed + cumulative interest
•Loan-to-Value (LTV): 85.0%. Deposit: £52,500.00 (15.0%).
•Stress Test (+2.0% rate rise): If interest rates rise to 6.50%, your monthly payment would increase by £355.14 to £2,008.74/mo.
•Total Upfront Cash Needed: £61,800.00 (including deposit, estimated £7,500.00 Stamp Duty, and legal fees).
How Your UK Mortgage Repayments Were Calculated
Loan: £297,500.00 • LTV: 85.0% • Term: 25 Years • Interest Rate: 4.50%
Loan-to-Value (LTV) & Loan Amount
£297,500.00 (85.0% LTV)Purchase Price £350,000.00 − Cash Deposit £52,500.00 = £297,500.00 Loan Borrowed
Lenders offer the most competitive fixed interest rates at LTV thresholds of 60%, 75%, and 80%. LTVs above 85% carry higher interest margins.
Monthly Amortisation & Repayment Breakdown
£1,653.60 / monthInitial Interest Payment: £1,115.63 / month
Initial Capital Repayment: £537.98 / month
Total Monthly Obligation: £1,653.60
Under a repayment mortgage, earlier years consist primarily of interest payments. As the loan amortises, each monthly instalment pays off an increasing proportion of loan principal.
Bank of England Stress Test (+2.0% Hike)
+£355.14/mo increaseAt 6.50% stressed rate: Monthly payment rises to £2,008.74 / month (+£355.14/mo)
UK mortgage lenders are required by the Financial Conduct Authority (FCA) and Prudential Regulation Authority (PRA) to stress-test your household affordability against future rate rises.
£1,653.60
How this calculator works
How it works
- 01Input your property purchase price, deposit amount, and selected loan term (15 to 40 years).
- 02Calculates your exact Loan-to-Value (LTV) percentage and total borrowing requirement.
- 03Calculates monthly repayments for Capital & Interest (repayment) or Interest-Only loans.
- 04Performs a Prudential Regulation Authority (PRA) affordability stress test, modeling monthly payment jumps under a +2% interest rate increase.
- 05Projects total cumulative interest paid over the mortgage life and computes total upfront completion cash needed (deposit + SDLT + legal fees).
Tax rules that apply
- •Capital & Interest vs Interest-Only: With a standard repayment mortgage, your monthly payment covers both interest and a portion of principal, ensuring the loan is paid off in full by the end of the term. With an interest-only mortgage, payments only cover accrued interest; the entire capital balance remains due at the end of the term.
- •Loan-to-Value (LTV) Pricing Tiers: Lenders price mortgage interest rates in discrete risk brackets: 60% LTV (lowest rates), 75%, 80%, 85%, 90%, and 95% LTV (highest rates). Increasing your deposit across a 5% threshold often unlocks significantly lower fixed interest rates.
- •FCA & PRA Affordability Stress Testing: Under Financial Conduct Authority Mortgage Conduct of Business (MCOB) rules, lenders must verify that borrowers can afford their mortgage if interest rates rise by 1% to 3% above their fixed rate or Standard Variable Rate (SVR).
- •Upfront Completion Cash Reserves: Borrowers must hold liquid cash beyond the mortgage deposit to cover Stamp Duty Land Tax, mortgage arrangement/booking fees (£0 to £1,500), valuation surveys, and conveyancing solicitors.
Current Tax Rates
| Tax / Deduction | Rate | Notes |
|---|---|---|
| Bank of England Base Rate | BoE Benchmark | Official central bank rate |
| 60% LTV Tier | Lowest fixed margins | Requires 40% deposit |
| 75% LTV Tier | Competitive mainstream tier | Requires 25% deposit |
| 90% LTV Tier | First-time buyer tier | Requires 10% deposit |
| 95% LTV Tier | High loan-to-value tier | Requires 5% deposit |
| Stress Test Rate Buffer | +2.0% to +3.0% | Prudential affordability test |
| Standard Mortgage Term | 25 to 30 years | Available up to 40 years |
What this calculator assumes
- Assumes monthly compounding interest over the full mortgage term.
- Monthly repayment assumes a fixed interest rate throughout the selected term.
- Estimated Stamp Duty assumes standard residential moving home rates under 2026/27 HMRC schedules.
Where our numbers come from
These calculators are based on official government tax rates and rules. We link directly to the source so you can verify everything yourself.
Bank of England — Official Bank Rate & Mortgage Market Data
Bank of England (Monetary Policy Committee)
HMRC — Stamp Duty Land Tax (SDLT) Residential Rates
HM Revenue & Customs (HMRC), United Kingdom
Frequently Asked Questions
How do mortgage lenders calculate monthly repayments in the UK?
For a repayment mortgage, lenders use the standard amortisation formula combining the loan principal, monthly interest rate, and total number of months. In the early years, the majority of your payment covers interest, with a smaller portion reducing principal. Over time, as the balance falls, more of each monthly payment goes towards paying off the capital.
What is Loan-to-Value (LTV) and why does it matter?
Loan-to-Value (LTV) is the percentage of the property value you borrow as a mortgage versus the cash deposit you provide. For example, a £50,000 deposit on a £200,000 home equals a 75% LTV. A lower LTV presents less risk to the lender, unlocking significantly lower interest rates and cheaper monthly payments.
What is the difference between repayment and interest-only mortgages?
With a repayment mortgage, you pay back both the interest and the borrowed capital each month, guaranteeing your home is 100% paid off at the end of the term. With an interest-only mortgage, your monthly payments are lower because you only pay the interest; you must have an approved repayment vehicle (such as investments, pensions, or sale of property) to repay the original loan capital when the term ends.
What is the Bank of England mortgage stress test?
Under regulatory guidelines from the Financial Conduct Authority (FCA), mortgage lenders must test whether you could still afford your monthly payments if interest rates rise by 1% to 3% above your rate. This stress test ensures households can withstand economic shocks or rate rises when fixed terms expire.
How much deposit do I need to buy a home in the UK?
The minimum deposit required by most UK mortgage lenders is 5% of the purchase price (a 95% LTV mortgage). However, saving a 10%, 15%, or 20% deposit significantly reduces your interest rate, cuts your monthly repayments, and broadens the range of lenders willing to approve your application.
What happens when my fixed-rate mortgage deal ends?
When your 2-year, 5-year, or 10-year fixed-rate deal ends, your mortgage automatically reverts to your lender's Standard Variable Rate (SVR), which is typically much higher (often 7% to 8%+). To avoid paying higher monthly repayments, borrowers typically remortgage with a new fixed rate or tracker deal 3 to 6 months before their current deal expires.
