Half-Life Calculator

Calculate radioactive decay, half-life, and carbon dating

Calculate Remaining Amount
Calculate Time Elapsed
Calculate Half-Life
Common Radioactive Isotopes
Isotope Half-Life Decay Type Common Use Action
Formulas
Decay Formula
N(t) = N₀ × (½)^(t/t½)
or N(t) = N₀ × e^(-λt)
Where:
  • N(t) = Amount remaining
  • N₀ = Initial amount
  • t = Time elapsed
  • t½ = Half-life
  • λ = Decay constant = ln(2)/t½
Key Facts
  • After 1 half-life: 50% remains
  • After 2 half-lives: 25% remains
  • After 3 half-lives: 12.5% remains
  • After 10 half-lives: ~0.1% remains
Quick Examples
Miscellaneous Services
Finance

Support This Free Tool

Every coffee helps keep the servers running. Every book sale funds the next tool I'm dreaming up. You're not just supporting a site — you're helping me build what developers actually need.

500K+ users
200+ tools
100% private
☕ One-time support Buy me a coffee 📚 Learn & support 9-Book Bundle - $9 Stay updated Follow @anish2good
Privacy Guarantee: Private keys you enter or generate are never stored on our servers. All tools are served over HTTPS.

Support This Free Tool

Every coffee helps keep the servers running. Every book sale funds the next tool I'm dreaming up. You're not just supporting a site — you're helping me build what developers actually need.

500K+ users
200+ tools
100% private
☕ One-time support Buy me a coffee 📚 Learn & support 9-Book Bundle - $9 Stay updated Follow @anish2good
Privacy Guarantee: Private keys you enter or generate are never stored on our servers. All tools are served over HTTPS.
Quick Access