9 calculators
Date & Time Calculators
Dates are where mental arithmetic fails fastest — months have different lengths, leap years move the goalposts, and lunar calendars drift against solar ones.
All Date & Time calculators
About these calculators
These nine tools handle both calendars. On the Gregorian side you can find your exact age, the gap between two people's ages, the span between any two dates, the weekday you were born and how long until your next birthday. On the Hijri side you can work out your Islamic age, the difference between two Hijri dates, and convert between the two calendars in either direction.
Leap years are handled properly throughout, including the century rule that catches out most quick calculations — 1900 was not a leap year, but 2000 was.
Which date or time calculator do you need?
| Your question | Use this |
|---|---|
| How old am I, exactly, in years, months and days? | Age calculator |
| What date is 90 days from today, or 30 business days? | Date calculator |
| How many days, weeks or months between two dates? | Date difference calculator |
| How many hours did I work, or how long between two times? | Time calculator |
| How many days until my birthday? | Birthday calculator |
| What is the age gap between two people? | Age difference calculator |
| What is today’s date in the Hijri calendar? | Gregorian to Hijri converter |
| When will I arrive if I leave now? | Arrival time calculator |
Date and time facts worth knowing
- A year has 365 days, or 366 in a leap year. Leap years fall every 4 years, except century years not divisible by 400.
- A Hijri (Islamic) year is about 354 days, so it moves about 11 days earlier each Gregorian year.
- For payroll, convert minutes to decimal hours by dividing by 60: 45 minutes is 0.75 hours.
- 90 days is not the same as 3 months — months have 28 to 31 days.