Radioisotope Decay Calculator (Tc-99m, F-18…)
Calculate the remaining activity of a medical or lab radioisotope after a time, with the decay-correction factor, free online.
About this calculator
Activity falls as A = A₀·e^(−λt) with λ = ln 2 ÷ half-life. Common half-lives: Tc-99m 6.01 h, F-18 109.8 min, Ga-68 67.7 min, I-131 8.02 d, Lu-177 6.65 d, Tl-201 73 h, In-111 2.80 d, C-11 20.4 min, Cs-137 30.2 y, Co-60 5.27 y.