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Calendar Math Instrument

Date Calculator

Add or subtract days, weeks, months, or years from any starting date to project deadlines, warranties, or milestone dates.

Exclude Weekends (Business Days Only)Skips Saturdays and Sundays when adding/subtracting days
Calculated Date
Resulting Target Date
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Day of the Week
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Day of Year
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Frequently Asked Questions

Everything you need to know about calculating time, durations, and work shifts.

How do you calculate a date 90 days from today?

Select today as the start date, select Add, enter 90 in the Days field, and the calculator instantly projects the target date, accounting for varying month lengths and leap years.

Can I calculate business days only (excluding weekends)?

Yes! Toggle on the Exclude weekends option. When adding days, the calculation steps only through Monday through Friday, skipping Saturdays and Sundays.

How does adding months handle months with differing day counts?

When adding months to a date like January 31st, the calculator automatically guards against month overflow. Adding 1 month to January 31st resolves to the last day of February (February 28 or 29 in leap years).