Mortgage Calculator UK: method, checked example and practical limits
Estimate UK repayment-mortgage or interest-only monthly payments in pounds. The pound-denominated results distinguish regular repayment from a payment that does not clear the loan capital.
Inputs used by this calculator
Mortgage Calculator UK uses the fields below. The starting values reproduce the page example; replace them with values from the same units and time period before using the result.
| Input | Starting example | Accepted value | How it is used |
|---|---|---|---|
| Mortgage type | Capital repayment | Capital repayment · Interest only | Chooses which Mortgage Calculator UK method or unknown the engine evaluates. |
| Property price (£) | 350,000 | 0.01 to 1000000000000 | Supplies the property price (£) quantity used by the published equation or result breakdown. |
| Deposit (£) | 70,000 | 0 to 1000000000000 | Supplies the deposit (£) quantity used by the published equation or result breakdown. |
| Annual interest rate (%) | 5 | 0 to 100 | Supplies the annual interest rate (%) quantity used by the published equation or result breakdown. |
| Term (years) | 25 | 1 to 50 | Supplies the term (years) quantity used by the published equation or result breakdown. |
Inputs and measurement conventions
The quantities used on this page are Mortgage type, Property price (£), Deposit (£), Annual interest rate (%), Term (years). Start with values for the same situation and read the units attached to each field. The field reference below shows supported choices and numerical limits.
An introductory rate may expire before the term ends. Arrangement fees and remortgaging costs are not inferred from the headline rate.
Method and equation
For repayment, amortize the balance monthly; for interest-only, charge the monthly interest while leaving principal outstanding.
Mortgage Calculator UK uses the following stated relationship: repayment=P×r/[1−(1+r)^−n]; interest-only=P×r. Its assumptions determine which question the answer can resolve.
repayment=P×r/[1−(1+r)^−n]; interest-only=P×rWorked calculation with the starting values
Mortgage type: Capital repayment; Property price (£): 350000; Deposit (£): 70000; Annual interest rate (%): 5; Term (years): 25. These starting values give 1,636.852116 estimated monthly payment (£). The calculation breakdown is Mortgage amount: 280,000; Loan-to-value: 80%; Total scheduled payments: 491,055.6349.
A £350,000 home with £70,000 deposit leaves a £280,000 mortgage for the selected term.
Reading the answer
The pound-denominated results distinguish regular repayment from a payment that does not clear the loan capital.
Mortgage amount: 280,000; Loan-to-value: 80%; Total scheduled payments: 491,055.6349. These intermediate quantities make the stated Mortgage Calculator UK model inspectable; they should be read together with the main answer rather than treated as independent guarantees.
Common errors and model boundaries
An introductory rate may expire before the term ends. Arrangement fees and remortgaging costs are not inferred from the headline rate.
Product fees, introductory periods, affordability checks, taxes, insurance and changing rates are not included.
Independent verification and next decision
The original principal remains payable unless repaid separately; monthly interest payments do not reduce it.
For the Mortgage Calculator UK method, compare repayment=P×r/[1−(1+r)^−n]; interest-only=P×r with the starting inputs and the calculation table. The linked MoneyHelper: mortgage repayment calculator and Financial Conduct Authority: consumer information references identify the relevant definitions, conventions or domain limitations. Retain intermediate precision when comparing a manually worked answer.
Mortgage Calculator UK worked-example ledger
| Quantity | Example value | Role |
|---|---|---|
| Mortgage type | Capital repayment | Entered assumption |
| Property price (£) | 350000 | Entered assumption |
| Deposit (£) | 70000 | Entered assumption |
| Annual interest rate (%) | 5 | Entered assumption |
| Term (years) | 25 | Entered assumption |
| Main answer | 1,636.852116 estimated monthly payment (£) | Calculated from the starting inputs |
| Mortgage amount | 280,000 | Intermediate or contextual output |
| Loan-to-value | 80% | Intermediate or contextual output |
| Total scheduled payments | 491,055.6349 | Intermediate or contextual output |
Frequently asked questions
What remains at the end of interest-only borrowing?
The original principal remains payable unless repaid separately; monthly interest payments do not reduce it.
Which relationship does the Mortgage Calculator UK use?
For repayment, amortize the balance monthly; for interest-only, charge the monthly interest while leaving principal outstanding. The displayed relationship is repayment=P×r/[1−(1+r)^−n]; interest-only=P×r.
What do the starting values produce in the Mortgage Calculator UK?
Mortgage type: Capital repayment; Property price (£): 350000; Deposit (£): 70000; Annual interest rate (%): 5; Term (years): 25. These starting values give 1,636.852116 estimated monthly payment (£). The calculation breakdown is Mortgage amount: 280,000; Loan-to-value: 80%; Total scheduled payments: 491,055.6349.
How should I interpret this Mortgage Calculator UK answer?
The pound-denominated results distinguish regular repayment from a payment that does not clear the loan capital.
Which input mistake most affects the Mortgage Calculator UK?
An introductory rate may expire before the term ends. Arrangement fees and remortgaging costs are not inferred from the headline rate.
What is outside this Mortgage Calculator UK model?
Product fees, introductory periods, affordability checks, taxes, insurance and changing rates are not included.
What to keep in mind
Product fees, introductory periods, affordability checks, taxes, insurance and changing rates are not included.
Results are rounded for display in US format, with money in dollars and cents; CSV exports keep full calculation precision. This is a calculation summary, not an official certificate.