Daily mortgage interest calculator UK
Estimate interest on a fixed mortgage balance over a specified number of days. Check the formula, worked example and limits before using your own figures.
Enter your figures
Illustrated interest for the period
Inputs changed. Select Calculate result to update your estimate.
Use your actual figures. Any prefilled price, fee, rate or return is an editable illustration, not a current product quote. Simple daily accrual, not a statement reconciliation. Enter the lender’s day-count basis; no changing balances, compounding or payment timing.
How the daily mortgage interest calculator uk works
Interest = balance × nominal annual rate × days ÷ day-count basis.
Data basis: mathematical formula using your inputs. Example prices and rates are illustrative, not current market quotes.
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Worked example: daily mortgage interest
This illustration uses the calculator’s example inputs. It is not a quote or a recommended financial decision.
- Mortgage balance (£)
- 200,000
- Nominal annual interest (%)
- 4.5
- Number of days
- 30
- Interest day-count basis
- 365
Illustrated interest for the period: £739.73
Interest = balance × nominal annual rate × days ÷ day-count basis.
Daily mortgage interest: questions answered
What does the daily mortgage interest calculation include?
Interest = balance × nominal annual rate × days ÷ day-count basis. Use your actual figures. Any prefilled price, fee, rate or return is an editable illustration, not a current product quote. Simple daily accrual, not a statement reconciliation. Enter the lender’s day-count basis; no changing balances, compounding or payment timing.
Using your result
Example inputs are a starting point. Replace them with your figures and select Calculate result. Results are rounded for display; calculations use unrounded values.
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