๐ฌ Science
Half-Life Calculator
Half-life is the time for half of a sample to decay, and because decay is exponential the remaining amount follows a power of one half. Ten half-lives leaves less than a tenth of a per cent, which is why radioactive waste stays hazardous for so long.
How it works
Initial amount
Half-life
Elapsed time
Time unit label
Amount remaining
Amount decayed
Remaining
Half-lives elapsed
Decay constant
Time to decay to 10 per cent
Frequently asked questions
How do I use the Half-Life Calculator?
Fill in the fields above โ the result recalculates instantly as you type. Everything runs in your browser, so the values you enter are never collected or stored.
Is this calculator free?
Yes. It is completely free, requires no account, and works on phones, tablets and desktops.