How do I calculate the days between two dates?

Enter the two dates above. The calculator shows the difference in days, weeks, months and years, and the equivalent count excluding weekends.

How do I calculate my age in days?

Enter your date of birth in the 'days from today' tool. The result is your age in days, weeks, months and years.

What day of the week was I born?

Enter your birthdate in the days-between tool — the calculator labels both dates with their weekday.

Date Calculator — Days Between, Days From Today, Age

Calculate the days between any two dates, find what date is X days from today, look up the day of the week for any date, or work out your age in days. Optional business-day mode excludes weekends.

Days Between Two Dates

Start date

End date

Exclude weekends (business days only)

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Days From / Before Today

Number of days

Direction

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Use a negative number or "Before today" to count backwards. Use this as an age-in-days lookup by entering your age in days.

Common Date Calculations

Days between dates: Sales contracts, loan tenors, project schedules.
Age in days/weeks: Pregnancy week tracking, infant age, "how old am I in days".
Business days: Payment terms (net-30 in business days), legal deadlines, project milestones.
Weekday lookup: "What day of the week was I born", historical date research.
Days until X: Countdown to weddings, birthdays, holidays, exam dates.

Business Days vs Calendar Days

Calendar days include every day on the calendar — Mondays through Sundays. Business days count only Monday through Friday. This calculator's business-days option excludes Saturday and Sunday but does not exclude national holidays — those vary by country.

Why "Months Between Dates" Is Tricky

Months have variable length (28–31 days), so "X months between dates" can mean two different things:

Calendar months: Number of month boundaries crossed (e.g., 31 January → 1 February = 1 month).
Average month-length: Total days ÷ 30.44 (the average days in a Gregorian month).

The result above shows both interpretations.