Date and time
Date difference, age and countdown. Calendar math, not time zones.
Age and dates
Date Calculator
Date calculator: 1 January 2026 to 31 January is 30 days. 1 January plus 90 days is 1 April.
Use calculator →Time Duration Calculator
Time duration: 8:00 to 16:30 is 8 hours 30 minutes. 22:00 to 6:00 the next day is 8 hours.
Use calculator →Add months to a date
Add years and months to a date: January 31, 2024 plus 1 month is February 29.
Use calculator →Hours Calculator
Hours calculator: 8:00 to 16:30 is 8 h 30 min. Overnight 22:00 to 6:00 is 8 hours.
Use calculator →Week Number
ISO week number: January 1, 2026 is week 1. December 31, 2024 is week 1 of 2025.
Use calculator →Business Days Calculator
Business days calculator: January 5 to 9, 2026 is 5 days. A listed holiday drops out.
Use calculator →Date calculator
Date calculator: new date = start date + N UTC civil days.
Use calculator →Age calculator
Age calculator: years, months, days = today − date of birth, with day and month borrow as in handwritten subtraction.
Use calculator →Countdown calculator
Countdown calculator: days = target date − today (UTC civil days).
Use calculator →Days between dates
Days between dates: days = end date − start date (UTC civil days).
Use calculator →Pregnancy and due date