CasviaTransparent amortisation maths.
Repayment mortgages use the standard annuity formula. Interest-only estimates use principal × monthly rate. LTV is loan divided by property price.
Read Casvia methodology →Property / Research Tool
UK Mortgage Calculator
Estimate monthly repayments, total interest and loan-to-value, then compare rate and deposit scenarios with the assumptions shown.
CalculationStandard amortisation
PrivacyRuns in your browser
Mortgage assumptions
£
£
%
25 years
No sign-up · No tracking · Runs in your browser
Base case / monthly repayment
£1,403
20%Deposit80%Loan to value
Research view
A £300,000 home with a £60,000 deposit means borrowing £240,000 (LTV 80%). At 5% over 25 years, that's £1,403/month — about £180,905 in interest over the term.
Rate sensitivity — 1% lower / base / 1% higher
| Scenario | Rate | Monthly | Total interest |
|---|
Illustrative scenarios only. Each assumes the selected rate remains constant for the full term.
Deposit sensitivity — compare higher deposit levels
| Scenario | Deposit | Loan | Monthly | Interest | LTV |
|---|
Deposit scenarios assume the same property price and interest rate.
Loan amount£240,000
Total interest paid£180,905
Total repaid£420,905
Remaining balance
Yearly breakdown — balance, principal and interest
| Year | Balance | Principal paid | Interest paid |
|---|
Important: This is an educational estimate based on the rate and assumptions you enter. It excludes lender fees and future rate changes. Actual mortgage pricing depends on lender criteria, product terms and your circumstances.
Current rate assumptions stay with you.
The calculator does not insert a live lender rate. You choose the rate, and the tool shows the sensitivity of the result.
- Bank of England — official Bank Rate
- MoneyHelper — mortgage guidance
How the mortgage calculation works
Enter the property price, deposit, annual interest rate and mortgage term. Casvia calculates the loan amount as property price minus deposit, then applies the standard repayment-mortgage annuity formula or an interest-only calculation depending on the mortgage type selected.
The result shows the estimated monthly payment, loan-to-value, total interest and total repaid. The rate and deposit sensitivity tables are illustrations only and are intended to show how the result changes when one assumption moves.
Example
For a £300,000 property with a £60,000 deposit, the loan is £240,000 and the LTV is 80%. At a fixed 5% rate over 25 years, the repayment estimate is about £1,403 a month, before product fees and any future rate changes.
UK mortgage context
- Mortgage rates vary by lender, product, LTV, affordability and borrower circumstances.
- A lower LTV can improve product availability, but there is no guaranteed rate for a particular deposit level.
- Fixed-rate periods are normally shorter than the full mortgage term, so a 25-year illustration at one rate is a comparison assumption rather than a forecast.
- Fees can materially affect the total cost of a mortgage and are not included in this calculator.
Frequently asked questions
How much can I borrow?
Borrowing limits depend on income, spending, deposit, credit profile and lender affordability tests. This tool estimates repayments for the loan you enter; it does not assess eligibility.
What deposit should I use?
A larger deposit reduces the loan and LTV. Lower LTV can improve access to products, but rates and criteria vary by lender.
Repayment or interest-only?
Repayment mortgages reduce the capital over time. Interest-only mortgages usually leave the capital outstanding until the end, so they require a separate repayment strategy.
Does this include mortgage fees?
No. Arrangement, valuation, legal and other costs are outside this illustration unless a product specifically includes them.
What if the rate changes?
Payments can change when a fixed period ends or on a variable-rate mortgage. Use the sensitivity table to compare assumptions rather than treating any rate as a forecast.
Can I overpay?
Many products permit some overpayment, but limits and early-repayment charges vary. Check the product terms and use Casvia's Mortgage Overpayment Calculator for a separate illustration.
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