Time & Date Calculator Hub
Calculate ages, find date differences, convert time zones, set countdowns, and track work hours — all free and instant.
Age Calculator
Calculate exact age in years, months, and days from any date of birth. See upcoming birthday countdown too.
Calculate Age →Date Difference Calculator
Find the exact number of days, weeks, months, and years between any two dates. Great for planning and deadlines.
Find Difference →Time Zone Converter
Convert times between any time zones worldwide. Schedule meetings across continents without the confusion.
Convert Time Zone →Countdown Calculator
Count down to any future date or event. See days, hours, minutes, and seconds remaining until your big moment.
Start Countdown →Work Hours Calculator
Track work hours, calculate overtime, and figure out your pay. Enter clock-in/out times and get totals instantly.
Track Hours →Time Add/Subtract
Add or subtract hours, minutes, and seconds from any time. Calculate arrival times, durations, and schedules.
Calculate Time →Essential Time & Date Reference
Handy facts for working with dates, time zones, and calendars.
Time Zone Basics
UTC is the global reference. EST = UTC-5, PST = UTC-8, GMT = UTC+0, IST = UTC+5:30, JST = UTC+9. Daylight saving shifts most US zones by 1 hour.
Leap Year Rules
A year is a leap year if divisible by 4, except centuries (divisible by 100) — unless also divisible by 400. So 2000 was a leap year, but 1900 was not.
24-Hour vs 12-Hour Time
Military/24-hour: 13:00 = 1:00 PM, 18:00 = 6:00 PM, 00:00 = midnight. Add 12 to PM hours (except 12 PM stays 12).
Work Hour Standards
Standard full-time: 40 hours/week (2,080/year). Overtime typically kicks in after 40 hours/week or 8 hours/day in some states.
Quick Reference Charts
Days in Each Month
- January: 31 days
- February: 28 (29 in leap year)
- March: 31, April: 30
- May: 31, June: 30
- July: 31, August: 31
- September: 30, October: 31
- November: 30, December: 31
Major US Time Zones
- EST/EDT: New York, Miami
- CST/CDT: Chicago, Dallas
- MST/MDT: Denver, Phoenix
- PST/PDT: LA, Seattle
- AKST: Alaska
- HST: Hawaii
Time Conversions
- 1 minute = 60 seconds
- 1 hour = 60 minutes = 3,600 seconds
- 1 day = 24 hours = 1,440 minutes
- 1 week = 7 days = 168 hours
- 1 year = 365.25 days (avg)
- 1 decade = 10 years
ISO Date Format
- Format: YYYY-MM-DD
- Example: 2026-02-08
- With time: 2026-02-08T14:30:00Z
- Why use it: Unambiguous globally
- Sorting: Sorts correctly as text
- Used by: Databases, APIs, logs
Need a Quick Time Calculation?
Start with our age calculator — the most popular time tool on CalcDrop.