Uranium-235 Half-Life: 700 Million Years
Uranium-235 has a half-life of approximately 700 million years; after 700 million years half the original amount remains.
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.
Uranium-235's extremely long half-life makes it useful for dating ancient geological formations.
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.