Date Calculator

Three Calculators in One

This date calculator combines three essential date-math tools. Days Between calculates the exact number of days, weeks, and months separating two dates. Add / Subtract finds the date that is a given number of days before or after a starting point. Age Calculator tells you your age in years, months, and days, plus how many days until your next birthday.

Practical Uses

• Contract & legal deadlines — Calculate exactly when a 90-day notice period or 30-day payment term expires.
• Project planning — Find how many working days remain until a milestone, or what date is 6 weeks from today.
• Subscription & renewal dates — Know exactly when a 1-year subscription that started on a given date will expire.
• Medical & health — Calculate gestational age, prescription durations, or time since a procedure.
• Travel & visas — Determine if you have stayed within a 90-day visa allowance, or plan your next entry date.

How Date Arithmetic Works

The days between calculation counts every calendar day inclusive of both endpoints when measuring a range. The result is expressed in total days, then broken down into whole weeks plus remainder days, and an approximate months figure based on the average month length of 30.44 days.

The add/subtract tool operates on exact 24-hour days rather than calendar months, so the result always lands on a specific weekday — useful for deadline calculations where "30 days from now" must be precise. Use our World Clock if you need to account for timezone differences in your date planning.