Half-Life 100 — Remaining After 300 Periods
Three half-lives (300 periods at half-life 100) leave exactly 12.5% of the initial amount.
How to use this tool
- Enter initial amount, half-life (time units) and elapsed time (same units) in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your remaining amount and the full breakdown beneath it.
After 3 half-lives, exactly 12.5% of any substance remains — verified here with a half-life of 100 periods.
Frequently asked questions
- What substances have known half-lives?
- Carbon-14 has a half-life of about 5,730 years (used in carbon dating). Uranium-238 has ~4.5 billion years. Iodine-131 used in medicine has ~8 days.
- Can I use this for non-radioactive decay?
- Yes — any process that halves on a fixed schedule (drug concentration, population loss, etc.) can be modelled this way.