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Radioactive Decay Law Calculator

Initial Activity:
Isotope Half Life (Check Below):
Decay Time:
Final Activity:



Radioactive decay is the process by which an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type transforming to an atom of a different type. There are three types of radioactive decays, namely alpha, beta and gamma. Radiation materials are dangerous. Exposure to radiation may cause genetic mutations leading to diseases like cancer.

Radioactive Decay Law formula is:
  N = N0e-(0.693t/T1/2)
Where:
N: Activity at time 0
N0: Initial activity
t: decay time
T1/2: half time of the radioactive material

The calculation assumes that 1 year = 365 days, and 1 month = 30 days.


Isotope Half Life Table

NameSymbolHalf LifeUnit
Actinium 227Ac-22721.77 Year
Aluminum 26Al-26720000 Year
Aluminum 29Al-290.11 Hour
Americium 241Am-241432 Year
Antimony 124Sb-12460.2 Day
Arsenic 74As-7417.9 Day
Astatine 211At-2117.21 Hour
Barium 128Ba-1282.43 Day
Barium 133Ba-13310.5 Year
Barium 140Ba-14012.8 Day
Beryllium 7Be-753.3 Day
Bismuth 207Bi-20738 Year
Bismuth 210Bi-2105.01 Day
Bromine 77Br-7757 Hour
Bromine 82Br-8235.34 Hour
Cadmium 109Cd-109453 Day
Calcium 45Ca-45162.61 Day
Carbon 11C-110.34 Hour
Carbon 14C-145730 Year
Cerium 141Ce-14132.5 Day
Cerium 144Ce-144284 Day
Cesium 134Cs-1342.06 Year
Cesium 137Cs-13730.17 Year
Chlorine 36Cl-36301000 Year
Chromium 51Cr-5127.7 Day
Cobalt 57Co-57270 Day
Cobalt 58Co-5871.3 Day
Cobalt 60Co-605.272 Year
Copper 61Cu-613.32 Hour
Copper 62Cu-620.163 Hour
Copper 64Cu-6412.7 Hour
Copper 67Cu-6761.88 Hour
Curium 244Cm-24418.12 Year
Europium 152Eu-15213 Year
Fluorine 18F-181.83 Hour
Gadolinium 153Gd-153242 Day
Gallium 67Ga-6778.2 Hour
Germanium 68Ge-68275 Day
Gold 198Au-1982.696 Day
Hafnium 181Hf-18142.5 Day
Hydrogen 3H-312.26 Year
Indium 111In-1112.81 Day
Indium 113mIn-113m1.66 Hour
Indium 114mIn-114m49.51 Day
Iodine 123I-12313.3 Hour
Iodine 125I-12560.2 Day
Iodine 131I-1318.04 Day
Iodine 132I-1322.26 Hour
Iridium 192Ir-19274.2 Day
Iron 52Fe-528.2 Hour
Iron 55Fe-552.73 Year
Iron 59Fe-5944.6 Day
Krypton 85Kr-8510.72 Year
Lanthanum 140La-14040.3 Hour
Lutetium 177Lu-1776.71 Day
Lead 210Pb-21022.3 Year
Manganese 52mMn-52m0.352 Hour
Manganese 54Mn-54313 Day
Manganese 56Mn-562.578 Hour
Mercury 197Hg-19765 Hour
Mercury 203Hg-20346.8 Day
Molybdenum 99Mo-9966.02 Hour
Neodymium 147Nd-14711.1 Day
Neptunium 237Np-2372140000 Year
Nickel 63Ni-63100.1 Year
Niobium 94Nb-9420000 Year
Niobium 95Nb-9535.15 Day
Nitrogen 13N-130.166 Hour
Oxygen 15O-150.03417 Hour
Phosphorus 32P-3214.26 Day
Phosphorus 33P-3325.34 Day
Polonium 208Po-2082.9 Year
Polonium 210Po-210138 Day
Potassium 38K-380.1285 Hour
Potassium 42K-4212.36 Hour
Promethium 147Pm-1472.62 Year
Plutonium 238Pu-23887.75 Year
Plutonium 239Pu-23924100 Year
Plutonium 240Pu-2406540 Year
Plutonium 242Pu-242380000 Year
Radium 226Ra-2261600 Year
Rubidium 82Rb-820.0208 Hour
Rubidium 86Rb-8618.7 Day
Rubidium 87Rb-874.75E10 Year
Ruthenium 103Ru-10339.5 Day
Ruthenium 106Ru-106367 Day
Scandium 46Sc-4683.8 Day
Selenium 75Se-75118.5 Day
Silver 110Ag-110252 Day
Silver 111Ag-1117.45 Day
Sodium 22Na-222.602 Year
Sodium 24Na-2415.02 Hour
Strontium 82Sr-8225 Day
Strontium 83Sr-831.35 Day
Strontium 85Sr-8564 Day
Strontium 89Sr-8952.7 Day
Strontium 90Sr-9028.8 Year
Sulphur 35S-3587.2 Day
Technetium 99mTc-99m6.05 Hour
Technetium 99Tc-99213000 Year
Thallium 201Tl-20172.9 Hour
Thallium 204Tl-2043.77 Year
Thorium 228Th-2281.913 Year
Thorium 229Th-2297340 Year
Thorium 230Th-23077000 Year
Thorium 232Th-23214000000000 Year
Tin 113Sn-113115 Day
Tin 119mSn-119m250 Day
Uranium 233U-233159000 Year
Uranium 234U-234244000 Year
Uranium 235U-235704000000 Year
Uranium 236U-23623400000 Year
Uranium 238U-2384470000000 Year
Vanadium 48V-4816 Day
Xenon 133Xe-1335.25 Day
Xenon 135Xe-1359.1 Hour
Yttrium 87Y-8780 Hour
Yttrium 90Y-9064 Hour
Zinc 62Zn-629.13 Hour
Zinc 65Zn-65244.1 Day