Birthday calculators | Birthday Odds

Check a birthday's historical rank, calculate a half or golden birthday, or explore shared-birthday odds.

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Choose a month and day to find its rank and share of recorded U.S. births from 1994 through 2014.

Find the date six calendar months later or halfway between yearly anniversaries. See how month ends and February 29 affect each method.

Find the birthday when your age matches the day of the month you were born, then compare it with a date of your choice.

Choose a group size to model the chance that at least two people share a birthday. Compare equally likely dates with historical U.S. birth shares.

For the sources and explanations, browse all birthday guides and research or read the methodology .