# Exact doubling time for an interest rate

## Description

For periodic compounding, the exact doubling time for an interest rate of r per period is a logarithmic formula, that can be used if we want to know the number of periods it takes for the initial value to rise by 100%.

Related formulas## Variables

T | Exact doubling time ( number of periods required) (dimensionless) |

r | Interest rate( i per period) (dimensionless) |