Date & Time Calculators
Every date and time calculator on the site, in one place - ages, countdowns, business scheduling, and time zone tools, grouped by what you're actually trying to work out.
Every tool runs the real calculation instantly in your browser as you type, and nothing you enter is saved. Jump to a section, or scroll through all 15.
Dates & ages
Working with calendar dates.
- Age Calculator - your exact age in years, months, and days, plus a countdown to your next birthday.
- Date Difference Calculator - the number of days, weeks, and months between two dates.
- Add/Subtract Date Calculator - add or subtract days, weeks, months, or years from any date.
- Day of the Week Calculator - find what day of the week any date falls on.
- Week Number Calculator - the ISO week number (1-53) for any date.
- Countdown Calculator - a live countdown to any future date and time.
Business & scheduling
Work days, payroll, and time tracking.
- Business Days Calculator - the number of weekdays between two dates, excluding weekends.
- Time Card Calculator - total hours worked across a full work week from clock-in and clock-out times.
- Time Duration Calculator - the exact gap between a start time and end time.
- Hours Calculator - add or subtract two time entries in hours and minutes.
Clock & time zones
Coordinating across time zones and tracking sleep.
- Time Zone Converter - convert a date and time between major world time zones, with daylight saving handled automatically.
- Sleep Calculator - suggested bedtimes or wake-up times based on full 90-minute sleep cycles.
Extras
A few less common but genuinely useful tools.
- Unix Timestamp Converter - convert between Unix time and a human-readable date, handy for developers.
- Leap Year Calculator - check if any year is a leap year, with the rule explained.
- Moon Phase Calculator - the approximate moon phase for any date.
Frequently asked questions
Are these date and time calculators free to use?
Yes - all 15 tools on this page are free, with no account or sign-up required.
Do these tools use my device's time zone?
Most calculations that involve "now" (like the Countdown Calculator) use your device's local time zone. The Time Zone Converter specifically is designed to work across different zones at once.
Is any of the information I enter saved?
No. Every calculation runs directly in your browser - nothing you type is sent to a server or stored anywhere.
Looking for a different category? Browse all calculators on the homepage. For articles and updates about these tools, see all Date & Time Calculators posts.