Date and time calculators
Date and time calculators convert clock formats, compute age, and find spans between calendar dates using the rules described on each page.
Calendar math follows the tool’s stated convention (for example 24-hour mapping of AM/PM). Time-zone and leap-second edge cases are called out only where the How it works text mentions them.
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Date Time
24-Hours Clock Calculator
Convert a 12-hour clock time to 24-hour format.
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Date Time
Age Calculator
Calculate age in years, months, and days from a birth date.
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Date Time
Age On Date Calculator
Exact age in years, months, and days on a target date.
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Date Time
Business Days Add Calculator
Add N business days (Mon–Fri) to a start date.
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Date Time
Date Calculator
Add or subtract days from a starting date.
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Date Time
Days Ago Calculator
Find the calendar date N days before today.
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Date Time
Days From Today Calculator
Find the calendar date N days after today.
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Date Time
Days Until Calculator
Count whole days from today until a target date.
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Date Time
Hours Ago Calculator
Find the date/time N hours before now.
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Date Time
Hours Calculator
Compute the number of hours between two date/times.
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Date Time
Hours From Now Calculator
Find the date/time N hours from now.
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Date Time
How Long Until Calculator
Show days, hours, and minutes remaining until a target.
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Date Time
Minutes Ago Calculator
Find the date/time N minutes before now.
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Minutes From Now Calculator
Find the date/time N minutes from now.
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Months Ago Calculator
Find the calendar date N months before today.
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Months From Now Calculator
Find the calendar date N months after today.
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Date Time
Time Calculator
Add hours and minutes to a starting date/time.
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Date Time
Timezone Offset Calculator
Local hour from UTC hour and offset, wrapped to 0–24.
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Date Time
Weeks Ago Calculator
Find the calendar date N weeks before today.
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Date Time
Weeks From Now Calculator
Find the calendar date N weeks after today.
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Date Time
Work Hours Calculator
Hours worked between start/end times with break.
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