Half Life Calculator

Enter three values from the following: Quantity Remains, Initial Quantity, Time and Half-life and click the ‘Calculate’ button to calculate the forth value.

Quantity Remains N(t) 

Initial Quantity N0          

Time t                                   

Half-life t1/2                        



Half-life is the time required for a quantity to reduce to half its initial value. Its calculation is based on a exponential decay equation.