Wolfram|Alpha

Computing...

Input information:

birthday problem |  \nnumber of people | 50 people


Probabilities that people have the same birthday:

 | probability | chance\nat least 2 the same | 0.9704 | ~~ 33 in 34\nat least 3 the same | 0.1264 | ~~ 1 in 8\n(assuming people chosen independently and all 365 possible birthdays are equally likely)