Investment doubling time calculator UK
Calculate how long a lump sum takes to double at a chosen constant effective rate. Check the formula, worked example and limits before using your own figures.
Enter your figures
Illustrative years to double
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. Positive constant growth, with no tax, fees or withdrawals. Not a forecast; the calculator uses the logarithmic formula rather than the Rule of 72 approximation.
How the investment doubling time calculator uk works
Doubling years = ln(2) ÷ ln(1 + annual rate).
Data basis: mathematical formula using your inputs. Example prices and rates are illustrative, not current market quotes.
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Worked example: investment doubling time
This illustration uses the calculator’s example inputs. It is not a quote or a recommended financial decision.
- Annual effective growth rate (%)
- 5
Illustrative years to double: 14.21 years
Doubling years = ln(2) ÷ ln(1 + annual rate).
Investment doubling time: questions answered
What does the investment doubling time calculation include?
Doubling years = ln(2) ÷ ln(1 + annual rate). Use your actual figures. Any prefilled price, fee, rate or return is an editable illustration, not a current product quote. Positive constant growth, with no tax, fees or withdrawals. Not a forecast; the calculator uses the logarithmic formula rather than the Rule of 72 approximation.
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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