# Isotopes of hafnium

Natural hafnium ($_{72}$Hf) consists of five observationally stable isotopes ($^{176}$Hf, $^{177}$Hf, $^{178}$Hf, $^{179}$Hf, and $^{180}$Hf) and one very long-lived radioisotope, $^{174}$Hf, with a half-life of 3.8×10$^{16}$ years. In addition, there are 34 known synthetic radioisotopes, the most stable of which is $^{182}$Hf with a half-life of 8.9×10$^6$ years. This extinct radionuclide is used in hafnium–tungsten dating to study the chronology of planetary differentiation.
No other radioisotope has a half-life over 1.87 years. Most isotopes have half-lives under 1 minute. There are also at least 27 nuclear isomers, the most stable of which is $^{178m2}$Hf with a half-life of 31 years. All isotopes of hafnium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{153}$Hf | 72 | 81 | 152.97069(32)# | 400# ms [>200 ns] | | | 1/2+# | | |
| $^{154}$Hf | 72 | 82 | 153.96486(32)# | 2(1) s | β$^+$ | $^{154}$Lu | 0+ | | |
| $^{154}$Hf | 72 | 82 | 153.96486(32)# | 2(1) s | α (rare) | $^{150}$Yb | 0+ | | |
| $^{154m}$Hf | 2721(50)# keV | 2721(50)# keV | 2721(50)# keV | 9(4) μs | IT | $^{154}$Hf | (10+) | | |
| $^{155}$Hf | 72 | 83 | 154.96317(32)# | 843(30) ms | β$^+$ | $^{155}$Lu | 7/2−# | | |
| $^{156}$Hf | 72 | 84 | 155.95940(16) | 23(1) ms | α | $^{152}$Yb | 0+ | | |
| $^{156m}$Hf | 1958.8(10) keV | 1958.8(10) keV | 1958.8(10) keV | 480(40) μs | α | $^{152}$Yb | (8+) | | |
| $^{157}$Hf | 72 | 85 | 156.95829(22)# | 115(1) ms | α (94%) | $^{153}$Yb | 7/2− | | |
| $^{157}$Hf | 72 | 85 | 156.95829(22)# | 115(1) ms | β$^+$ (6%) | $^{157}$Lu | 7/2− | | |
| $^{158}$Hf | 72 | 86 | 157.954801(19) | 2.85(7) s | β$^+$ (55.7%) | $^{158}$Lu | 0+ | | |
| $^{158}$Hf | 72 | 86 | 157.954801(19) | 2.85(7) s | α (44.3%) | $^{154}$Yb | 0+ | | |
| $^{159}$Hf | 72 | 87 | 158.953996(18) | 5.20(10) s | β$^+$ (65%) | $^{159}$Lu | 7/2− | | |
| $^{159}$Hf | 72 | 87 | 158.953996(18) | 5.20(10) s | α (35%) | $^{155}$Yb | 7/2− | | |
| $^{160}$Hf | 72 | 88 | 159.950683(10) | 13.6(2) s | β$^+$ (99.3%) | $^{160}$Lu | 0+ | | |
| $^{160}$Hf | 72 | 88 | 159.950683(10) | 13.6(2) s | α (0.7%) | $^{156}$Yb | 0+ | | |
| $^{161}$Hf | 72 | 89 | 160.950278(25) | 18.4(4) s | β$^+$ (99.71%) | $^{161}$Lu | (7/2−) | | |
| $^{161}$Hf | 72 | 89 | 160.950278(25) | 18.4(4) s | α (0.29%) | $^{157}$Yb | (7/2−) | | |
| $^{161m}$Hf | 329.0(5) keV | 329.0(5) keV | 329.0(5) keV | 4.8(2) μs | IT | $^{161}$Yb | (13/2+) | | |
| $^{162}$Hf | 72 | 90 | 161.9472155(96) | 39.4(9) s | β$^+$ (99.99%) | $^{162}$Lu | 0+ | | |
| $^{162}$Hf | 72 | 90 | 161.9472155(96) | 39.4(9) s | α (0.008%) | $^{158}$Yb | 0+ | | |
| $^{163}$Hf | 72 | 91 | 162.947107(28) | 40.0(6) s | β$^+$ | $^{163}$Lu | (5/2−) | | |
| $^{164}$Hf | 72 | 92 | 163.944371(17) | 111(8) s | β$^+$ | $^{164}$Lu | 0+ | | |
| $^{165}$Hf | 72 | 93 | 164.944567(30) | 76(4) s | β$^+$ | $^{165}$Lu | (5/2−) | | |
| $^{166}$Hf | 72 | 94 | 165.942180(30) | 6.77(30) min | β$^+$ | $^{166}$Lu | 0+ | | |
| $^{167}$Hf | 72 | 95 | 166.942600(30) | 2.05(5) min | β$^+$ | $^{167}$Lu | (5/2)− | | |
| $^{168}$Hf | 72 | 96 | 167.940568(30) | 25.95(20) min | EC (98%) | $^{168}$Lu | 0+ | | |
| $^{168}$Hf | 72 | 96 | 167.940568(30) | 25.95(20) min | β$^+$ (2%) | $^{168}$Lu | 0+ | | |
| $^{169}$Hf | 72 | 97 | 168.941259(30) | 3.24(4) min | β$^+$ | $^{169}$Lu | (5/2−) | | |
| $^{170}$Hf | 72 | 98 | 169.939609(30) | 16.01(13) h | EC | $^{170}$Lu | 0+ | | |
| $^{171}$Hf | 72 | 99 | 170.940492(31) | 12.1(4) h | β$^+$ | $^{171}$Lu | 7/2+ | | |
| $^{171m}$Hf | 21.93(9) keV | 21.93(9) keV | 21.93(9) keV | 29.5(9) s | IT | $^{171}$Hf | 1/2− | | |
| $^{172}$Hf | 72 | 100 | 171.939450(26) | 1.87(3) y | EC | $^{172}$Lu | 0+ | | |
| $^{172m}$Hf | 2005.84(11) keV | 2005.84(11) keV | 2005.84(11) keV | 163(3) ns | IT | $^{172}$Hf | (8−) | | |
| $^{173}$Hf | 72 | 101 | 172.940513(30) | 23.6(1) h | β$^+$ | $^{173}$Lu | 1/2− | | |
| $^{173m1}$Hf | 107.16(5) keV | 107.16(5) keV | 107.16(5) keV | 180(8) ns | IT | $^{173}$Hf | 5/2− | | |
| $^{173m2}$Hf | 197.47(10) keV | 197.47(10) keV | 197.47(10) keV | 160(40) ns | IT | $^{173}$Hf | 7/2+ | | |
| $^{174}$Hf | 72 | 102 | 173.9400484(24) | 3.8+1.7 −0.9×10$^{16}$ y | α | $^{170}$Yb | 0+ | 0.0016(12) | |
| $^{174m1}$Hf | 1549.26(4) keV | 1549.26(4) keV | 1549.26(4) keV | 138(4) ns | IT | $^{174}$Hf | 6+ | | |
| $^{174m2}$Hf | 1797.59(7) keV | 1797.59(7) keV | 1797.59(7) keV | 2.39(4) μs | IT | $^{174}$Hf | 8− | | |
| $^{174m3}$Hf | 3312.07(6) keV | 3312.07(6) keV | 3312.07(6) keV | 3.7(2) μs | IT | $^{174}$Hf | 14+ | | |
| $^{175}$Hf | 72 | 103 | 174.9415114(25) | 70.65(19) d | EC | $^{175}$Lu | 5/2− | | |
| $^{175m1}$Hf | 125.89(12) keV | 125.89(12) keV | 125.89(12) keV | 53.7(15) μs | IT | $^{175}$Hf | 1/2− | | |
| $^{175m2}$Hf | 1433.41(12) keV | 1433.41(12) keV | 1433.41(12) keV | 1.10(8) μs | IT | $^{175}$Hf | 19/2+ | | |
| $^{175m3}$Hf | 3015.6(4) keV | 3015.6(4) keV | 3015.6(4) keV | 1.21(15) μs | IT | $^{175}$Hf | 35/2− | | |
| $^{175m4}$Hf | 4636.2(12) keV | 4636.2(12) keV | 4636.2(12) keV | 1.9(1) μs | IT | $^{175}$Hf | 45/2+ | | |
| $^{176}$Hf | 72 | 104 | 175.9414098(16) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.0526(70) | |
| $^{176m1}$Hf | 1333.07(7) keV | 1333.07(7) keV | 1333.07(7) keV | 9.6(3) μs | IT | $^{176}$Hf | 6+ | | |
| $^{176m2}$Hf | 1559.31(9) keV | 1559.31(9) keV | 1559.31(9) keV | 9.9(2) μs | IT | $^{176}$Hf | 8− | | |
| $^{176m3}$Hf | 2865.8(7) keV | 2865.8(7) keV | 2865.8(7) keV | 401(6) μs | IT | $^{176}$Hf | 14− | | |
| $^{176m4}$Hf | 4863.6(9) keV | 4863.6(9) keV | 4863.6(9) keV | 43(4) μs | IT | $^{176}$Hf | 22− | | |
| $^{177}$Hf | 72 | 105 | 176.9432302(15) | Observationally Stable | Observationally Stable | Observationally Stable | 7/2− | 0.1860(16) | |
| $^{177m1}$Hf | 1315.4502(8) keV | 1315.4502(8) keV | 1315.4502(8) keV | 1.09(5) s | IT | $^{177}$Hf | 23/2+ | | |
| $^{177m2}$Hf | 1342.4(10) keV | 1342.4(10) keV | 1342.4(10) keV | 55.9(12) μs | IT | $^{177}$Hf | (19/2−) | | |
| $^{177m3}$Hf | 2740.02(15) keV | 2740.02(15) keV | 2740.02(15) keV | 51.4(5) min | IT | $^{177}$Hf | 37/2− | | |
| $^{178}$Hf | 72 | 106 | 177.9437083(15) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.2728(28) | |
| $^{178m1}$Hf | 1147.416(6) keV | 1147.416(6) keV | 1147.416(6) keV | 4.0(2) s | IT | $^{178}$Hf | 8− | | |
| $^{178m2}$Hf | 2446.09(8) keV | 2446.09(8) keV | 2446.09(8) keV | 31(1) y | IT | $^{178}$Hf | 16+ | | |
| $^{178m3}$Hf | 2572.4(3) keV | 2572.4(3) keV | 2572.4(3) keV | 68(2) μs | IT | $^{178}$Hf | 14− | | |
| $^{179}$Hf | 72 | 107 | 178.9458257(15) | Observationally Stable | Observationally Stable | Observationally Stable | 9/2+ | 0.1362(11) | |
| $^{179m1}$Hf | 375.0352(25) keV | 375.0352(25) keV | 375.0352(25) keV | 18.67(4) s | IT | $^{179}$Hf | 1/2− | | |
| $^{179m2}$Hf | 1106.412(33) keV | 1106.412(33) keV | 1106.412(33) keV | 25.00(17) d | IT | $^{179}$Hf | 25/2− | | |
| $^{179m3}$Hf | 3775.2(21) keV | 3775.2(21) keV | 3775.2(21) keV | 15(5) μs | IT | $^{179}$Hf | (43/2+) | | |
| $^{180}$Hf | 72 | 108 | 179.9465595(15) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.3508(33) | |
| $^{180m1}$Hf | 1141.552(15) keV | 1141.552(15) keV | 1141.552(15) keV | 5.53(2) h | IT (99.69%) | $^{180}$Hf | 8− | | |
| $^{180m1}$Hf | 1141.552(15) keV | 1141.552(15) keV | 1141.552(15) keV | 5.53(2) h | β$^−$ (0.31%) | $^{180m1}$Ta | 8− | | |
| $^{180m2}$Hf | 1374.36(4) keV | 1374.36(4) keV | 1374.36(4) keV | 570(20) μs | IT | $^{180}$Hf | 4− | | |
| $^{180m3}$Hf | 2485.5(5) keV | 2485.5(5) keV | 2485.5(5) keV | 0.94(11) μs | IT | $^{180}$Hf | 12+ | | |
| $^{180m4}$Hf | 3599.0(10) keV | 3599.0(10) keV | 3599.0(10) keV | 90(10) μs | IT | $^{180}$Hf | (18−) | | |
| $^{181}$Hf | 72 | 109 | 180.9491108(15) | 42.39(6) d | β$^−$ | $^{181}$Ta | 1/2− | | |
| $^{181m1}$Hf | 595.27(4) keV | 595.27(4) keV | 595.27(4) keV | 80(5) μs | IT | $^{181}$Hf | (9/2+) | | |
| $^{181m2}$Hf | 1043.5(8) keV | 1043.5(8) keV | 1043.5(8) keV | ~100 μs | IT | $^{181}$Hf | (17/2+) | | |
| $^{181m3}$Hf | 1741.9(13) keV | 1741.9(13) keV | 1741.9(13) keV | 1.5(5) ms | IT | $^{181}$Hf | (25/2−) | | |
| $^{182}$Hf | 72 | 110 | 181.9505637(66) | 8.90(9)×10$^6$ y | β$^−$ | $^{182}$Ta | 0+ | | |
| $^{182m1}$Hf | 1172.87(18) keV | 1172.87(18) keV | 1172.87(18) keV | 61.5(15) min | β$^−$ (54%) | $^{182}$Ta | 8− | | |
| $^{182m1}$Hf | 1172.87(18) keV | 1172.87(18) keV | 1172.87(18) keV | 61.5(15) min | IT (46%) | $^{182}$Hf | 8− | | |
| $^{182m2}$Hf | 2571.3(12) keV | 2571.3(12) keV | 2571.3(12) keV | 40(10) μs | IT | $^{182}$Hf | (13+) | | |
| $^{183}$Hf | 72 | 111 | 182.953533(32) | 1.018(2) h | β$^−$ | $^{183}$Ta | (3/2−) | | |
| $^{183m}$Hf | 1464(64) keV | 1464(64) keV | 1464(64) keV | 40(30) s | IT | $^{183}$Hf | 27/2−# | | |
| $^{184}$Hf | 72 | 112 | 183.955449(43) | 4.12(5) h | β$^−$ | $^{184}$Ta | 0+ | | |
| $^{184m1}$Hf | 1272.2(4) keV | 1272.2(4) keV | 1272.2(4) keV | 48(10) s | IT | $^{184}$Hf | 8− | | |
| $^{184m2}$Hf | 2477(10) keV | 2477(10) keV | 2477(10) keV | 16(7) min | | | 15+# | | |
| $^{185}$Hf | 72 | 113 | 184.958862(69) | 3.5(6) min | β$^−$ | $^{185}$Ta | (9/2−) | | |
| $^{186}$Hf | 72 | 114 | 185.960897(55) | 2.6(12) min | β$^−$ | $^{186}$Ta | 0+ | | |
| $^{186m}$Hf | 2968(43) keV | 2968(43) keV | 2968(43) keV | >20 s | | | 17+# | | |
| $^{187}$Hf | 72 | 115 | 186.96457(22)# | 14# s [>300 ns] | | | 9/2−# | | |
| $^{187m}$Hf | 500(300)# keV | 500(300)# keV | 500(300)# keV | 270(80) ns | IT | $^{187}$Hf | 3/2−# | | |
| $^{188}$Hf | 72 | 116 | 187.96690(32)# | 7# s [>300 ns] | | | 0+ | | |
| $^{189}$Hf | 72 | 117 | 188.97085(32)# | 400# ms [>300 ns] | | | 3/2−# | | |
| $^{190}$Hf | 72 | 118 | 189.97338(43)# | 600# ms [>300 ns] | | | 0+ | | |
| $^{191}$Hf | 72 | 119 | | | | | | | |
| $^{192}$Hf | 72 | 120 | | | | | 0+ | | |
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* ↑ $^m$Hf – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* ↑ Bold half-life – nearly stable, half-life longer than age of universe.
* 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ primordial radionuclide
* ↑ Theorized to also undergo β$^+$β$^+$ decay to $^{174}$Yb
* ↑ Used in lutetium-hafnium dating
* ↑ Believed to undergo α decay to $^{172}$Yb
* ↑ Believed to undergo α decay to $^{173}$Yb with a half-life over 1.3×10$^{18}$ y.
* ↑ Believed to undergo α decay to $^{174}$Yb
* ↑ Believed to undergo α decay to $^{175}$Yb
* ↑ Believed to undergo α decay to $^{176}$Yb
* ↑ Extinct radionuclide, used in hafnium–tungsten dating