These are simple calculators for the Wigner 3-j, 6-j and 9-j symbols, used to couple angular momenta in quantum mechanics. For further information on these symbols, check out their respective Wikipedia pages: 3-j, 6-j and 9-j. For a calculator that can give exact values (not floating point answers), see Anthony Stone's page. These have been tested extensively, but there is still the possibility that the results can be incorrect.