Calculator
Radioactive decay calculator
Calculate radioactive decay and daughter build-up from an initial activity. The table lists half-lives and the strongest reported gamma line.
Radioactive decay calculator
Calculate activity and daughter build-up.
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Half-lives and gamma lines
| Isotope | Half-life | Main gamma line (keV) |
|---|---|---|
| H-3 | 12.32 ± 0.02 y | None reported |
| C-14 | 5700 ± 30 y | None reported |
| F-18 | 109.77 ± 0.05 min | None reported |
| Na-22 | 2.6018 ± 0.0022 y | 1274.537 |
| P-32 | 14.266 ± 0.004 d | None reported |
| K-40 | 1248000000 ± 3000000 y | 1460.82 |
| Co-57 | 271.74 ± 0.06 d | 122.06065 |
| Co-60 | 1925.28 ± 0.14 d | 1332.492 |
| Ga-68 | 67.71 ± 0.08 min | 1077.34 |
| Ge-68 | 270.95 ± 0.16 d | None reported |
| Sr-90 | 28.91 ± 0.03 y | None reported |
| Y-90 | 64.05 ± 0.05 h | None reported |
| Zr-89 | 78.41 ± 0.12 h | 909.15 |
| Mo-99 | 65.924 ± 0.006 h | 739.5 |
| Tc-99m | 6.0072 ± 0.0009 h | 140.511 |
| In-111 | 2.8047 ± 0.0004 d | 245.35 |
| I-123 | 13.223 ± 0.0019 h | 159 |
| I-125 | 59.4 ± 0.01 d | 35.4925 |
| I-131 | 8.0252 ± 0.0006 d | 364.489 |
| Xe-133 | 5.2475 ± 0.0005 d | 80.9979 |
| Cs-137 | 30.08 ± 0.09 y | 661.657 |
| Ba-133 | 10.551 ± 0.011 y | 356.0129 |
| Ba-137m | 2.552 ± 0.001 min | 661.657 |
| Sm-153 | 46.284 ± 0.004 h | 103.18012 |
| Lu-177 | 6.6443 ± 0.0009 d | 208.3662 |
| Yb-169 | 32.018 ± 0.005 d | 63.12044 |
| Ir-192 | 73.829 ± 0.011 d | 316.50618 |
| Tl-201 | 3.042 ± 0.0016 d | 167.43 |
| Ra-223 | 11.4366 ± 0.0028 d | 269.463 |
| Ra-226 | 1603 ± 8 y | 186.211 |
| Rn-222 | 3.8222 ± 0.0009 d | 510 |
| Th-232 | 14000000000 ± 100000000 y | 63.81 |
| U-235 | 704000000 ± 1000000 y | 185.713 |
| U-238 | 4468000000 ± 3000000 y | 49.55 |
| Pu-239 | 24110 ± 30 y | 12.975 |
| Am-241 | 432.6 ± 0.6 y | 59.5409 |
| Cf-252 | 2.647 ± 0.003 y | 43.399 |
| Se-75 | 119.78 ± 0.05 d | 264.6576 |
| Kr-85 | 10.739 ± 0.014 y | 513.997 |
| Pb-210 | 22.2 ± 0.22 y | 46.539 |
Cite this
ScienceShot. Radioactive decay calculator. https://scienceshot.com/radioactive-decay-calculator.
Source: NuDat 3.0 database, National Nuclear Data Center, Brookhaven National Laboratory; ENSDF evaluations.
ScienceShot calculation.
Cite this page
ScienceShot. (2026). Radioactive decay calculator [Online calculator]. https://scienceshot.com/radioactive-decay-calculator
@misc{scienceshot-radioactive-decay-calculator-2026,
author = {{ScienceShot}},
title = {{Radioactive decay calculator}},
year = {2026},
note = {Online calculator},
url = {https://scienceshot.com/radioactive-decay-calculator}
}