Simple interest calculator UK
Calculate non-compounding interest on a fixed principal over a stated period. Check the formula, worked example and limits before using your own figures.
Enter your figures
Simple interest
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. No compounding, tax, fees or rate changes. Use the account’s actual day-count convention.
How the simple interest calculator uk works
Interest = principal × annual rate × days ÷ basis.
Data basis: mathematical formula using your inputs. Example prices and rates are illustrative, not current market quotes.
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Worked example: simple interest
This illustration uses the calculator’s example inputs. It is not a quote or a recommended financial decision.
- Principal (£)
- 1,000
- Nominal annual interest (%)
- 4
- Days
- 180
- Day-count basis
- 365
Simple interest: £19.73
Interest = principal × annual rate × days ÷ basis.
Simple interest: questions answered
What does the simple interest calculation include?
Interest = principal × annual rate × days ÷ basis. Use your actual figures. Any prefilled price, fee, rate or return is an editable illustration, not a current product quote. No compounding, tax, fees or rate changes. Use the account’s actual day-count convention.
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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