Most of the isotope data on this site has been obtained from the National Nuclear Data Center.
Naturally Occurring Isotopes
Einsteinium has no naturally occurring isotopes.
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 240 | No Data Available | Alpha Decay (suspected) | No Data Available |
| Electron Capture (suspected) | No Data Available | ||
| 241 | 8 seconds | Electron Capture | No Data Available |
| Alpha Decay | No Data Available | ||
| 242 | 17.8 seconds | Alpha Decay | 57.00% |
| Electron Capture | 43.00% | ||
| 243 | 23 seconds | Alpha Decay | 61.00% |
| Electron Capture | 39.00% | ||
| Spontaneous Fission | < 1.00% | ||
| 244 | 37 seconds | Electron Capture | 96.00% |
| Alpha Decay | 4.00% | ||
| 245 | 1.1 minutes | Electron Capture | 60.00% |
| Alpha Decay | 40.00% | ||
| 246 | 7.5 minutes | Alpha Decay | 9.90% |
| Electron Capture | 90.10% | ||
| 247 | 4.55 minutes | Electron Capture | ~ 93.00% |
| Alpha Decay | ~ 7.00% | ||
| 247m | 625 days | Alpha Decay | No Data Available |
| 248 | 27 minutes | Electron Capture | 99.70% |
| Alpha Decay | ~ 0.25% | ||
| 249 | 102.2 minutes | Electron Capture | 99.43% |
| Alpha Decay | 0.57% | ||
| 250 | 8.6 hours | Electron Capture | > 97.00% |
| Alpha Decay | < 3.00% | ||
| 250m | 2.22 hours | Electron Capture | <= 100.00% |
| 251 | 33 hours | Electron Capture | 99.50% |
| Alpha Decay | 0.50% | ||
| 252 | 471.7 days | Alpha Decay | 78.00% |
| Electron Capture | 22.00% | ||
| 253 | 20.47 days | Spontaneous Fission | 8.7×10-6 % |
| Alpha Decay | 100.00% | ||
| 254 | 275.7 days | Alpha Decay | 100.00% |
| Beta-minus Decay | 1.7×10-4 % | ||
| Spontaneous Fission | < 3.0×10-6 % | ||
| 254m | 39.3 hours | Alpha Decay | 0.32% |
| Electron Capture | 0.08% | ||
| Spontaneous Fission | < 0.05% | ||
| Beta-minus Decay | 98.00% | ||
| Isomeric Transition | < 3.00% | ||
| 255 | 39.8 days | Beta-minus Decay | 92.00% |
| Alpha Decay | 8.00% | ||
| Spontaneous Fission | 4.1×10-3 % | ||
| 256 | 25.4 minutes | Beta-minus Decay | 100.00% |
| 256m | 7.6 hours | Beta-minus Decay | 100.00% |
| 257 | 7.7 days | Beta-minus Decay | No Data Available |
| Spontaneous Fission | No Data Available | ||
| 258 | No Data Available | Alpha Decay (suspected) | No Data Available |
| Electron Capture (suspected) | No Data Available |
This page is maintained by Steve Gagnon.