Calculate how much time has passed since a past date.
Both dates are converted to a day count so the elapsed span is a subtraction. Larger units are derived from the day total using average lengths. Anniversaries, warranty periods and eligibility windows all depend on this figure, and month-boundary errors are the usual source of disputes.
Time Since
Days since = today’s day number − the past date’s day number
Days since = today’s day number − the past date’s day number Both dates are converted to a day count so the elapsed span is a subtraction. Larger units are derived from the day total using average lengths.
Anniversaries, warranty periods and eligibility windows all depend on this figure, and month-boundary errors are the usual source of disputes.
This calculator takes 6 inputs: Past date year, Past date month, Past date day, Today year, Today month, Today day. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.