Enter the initial quantity, final quantity, and total time passed to calculate the half-life. Half-life is defined as the time it takes for a value to decrease by half. This is most often used in nuclear physics.

## Half-Life Formula

So, how do you calculate half-life? Half-life is calculated using the exponential decay formulas, as shown below.

- Where N0 is the initial quantity
- N(t) is the quantity remaining after some time
- t1/2 is the half-life, and t is time.

This can be further simplified into the following to calculate half-life.

## What is half-life?

A half-life is the time it takes a given substance to deteriorate or lose half of its mass.

Half-life is a term mostly used in nuclear physics to describe the rate of decay of radioactive substances. As a result, the formula above includes the decay constant of the material. However, the half-life can also be calculated simply through time passed, initial quantity, and final quantity by re-arranging the very first equation above.

The idea of half-life is that since it’s exponential decay, it starts off losing a lot of mass to start, then slowly slows down. It will never actually reach absolute 0. Yet, of course, it would eventually approach an amount considered negligible.

## How to calculate a half-life?

How to calculate a half-life?

**First, you must determine the initial quantity of your substance**For this example we will assume that to be 10 grams.

**Next, you need to measure the time that has passed.**For this example we will assume 10 seconds.

**Next, you need to measure the final quantity of substance**For this example we will assume 9 grams.

**Finally, plug the needed information into the formula**79.84 is the half life.

## FAQ

**What is a half life?**

Half-life is the time it takes a given substance to deteriorate or lose half of its mass.