| Symbol | Mass Number | Relative Atomic Mass | Isotopic Composition |
|---|---|---|---|
| 126Pm | 126 | 125.95752(54)# | |
| 127Pm | 127 | 126.95163(64)# | |
| 128Pm | 128 | 127.94842(43)# | |
| 129Pm | 129 | 128.94316(43)# | |
| 130Pm | 130 | 129.94045(32)# | |
| 131Pm | 131 | 130.93587(21)# | |
| 132Pm | 132 | 131.93375(21)# | |
| 133Pm | 133 | 132.929780(50) | |
| 134Pm | 134 | 133.928350(60) | |
| 135Pm | 135 | 134.924880(60) | |
| 136Pm | 136 | 135.923570(80) | |
| 137Pm | 137 | 136.920479(14) | |
| 138Pm | 138 | 137.919548(30) | |
| 139Pm | 139 | 138.916804(14) | |
| 140Pm | 140 | 139.916040(40) | |
| 141Pm | 141 | 140.913555(15) | |
| 142Pm | 142 | 141.912874(27) | |
| 143Pm | 143 | 142.910933(4) | |
| 144Pm | 144 | 143.912591(3) | |
| 145Pm | 145 | 144.912749(3) | |
| 146Pm | 146 | 145.914696(5) | |
| 147Pm | 147 | 146.9151385(26) | |
| 148Pm | 148 | 147.917475(7) | |
| 149Pm | 149 | 148.918334(4) | |
| 150Pm | 150 | 149.920984(22) | |
| 151Pm | 151 | 150.921207(6) | |
| 152Pm | 152 | 151.923497(28) | |
| 153Pm | 153 | 152.924117(12) | |
| 154Pm | 154 | 153.926460(50) | |
| 155Pm | 155 | 154.928100(30) | |
| 156Pm | 156 | 155.931060(40) | |
| 157Pm | 157 | 156.93304(12) | |
| 158Pm | 158 | 157.93656(14) | |
| 159Pm | 159 | 158.93897(21)# | |
| 160Pm | 160 | 159.94299(32)# | |
| 161Pm | 161 | 160.94586(54)# | |
| 162Pm | 162 | 161.95029(75)# | |
| 163Pm | 163 | 162.95368(86)# |