All DateKit tools

Choose the date calculation you need

The hub groups six related tasks into one consistent, private, and mobile-friendly experience.

Personal date calculation

Age Calculator

See age in years, months, days, weeks, and time until the next birthday.

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Compare two dates

Date Difference

Compare two dates in calendar years, months, weeks, and total days.

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Workday planning

Business Days Calculator

Count working days while excluding weekends and optional custom dates.

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Date adjustment

Add or Subtract Dates

Move a date forward or backward by years, months, weeks, or days.

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Event countdown

Days Until a Date

See the time remaining until an event or the time elapsed since it.

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Personal countdown

Birthday Countdown

Track the next birthday, remaining days, and the age that will be reached.

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Which date calculator should you use?

Use the age calculator for a birth date, date difference for a fixed range, business days for work schedules, add or subtract for a resulting date, and the countdown tools when one side of the calculation is today.

Consistent date rules across every tool

DateKit distinguishes calendar duration from total days, exposes inclusive options when they matter, and explains exceptions such as leap-day birthdays and months without a matching day number.

Designed for browser-only calculations

DateKit does not need an account or database. Every calculation runs directly in your browser and the entered dates are not stored.