Time Calculators
Calculate the time between dates, your exact age, how many days until an event, and convert between time zones — our free time calculators handle every date and time calculation you need.
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Date & Age
Date difference, age calculator, and days until calculators
Time Zones & Hours
Time zone conversion and hours between times
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Time Glossary — Key Terms Explained
- UTC (Coordinated Universal Time)
- The primary time standard by which the world regulates clocks. UTC+0 is the reference point — London is UTC+0 in winter (GMT), UTC+1 in summer (BST). New York is UTC-5 (EST) or UTC-4 (EDT).
- Leap Year
- A year with 366 days (February has 29 days). Occurs every 4 years, except for years divisible by 100, unless also divisible by 400. 2000 was a leap year; 1900 was not. Next leap year: 2028.
- ISO 8601
- International date format standard: YYYY-MM-DD. Unambiguous internationally — '2024-06-15' is June 15, 2024 in any country. Avoids confusion between MM/DD/YYYY (US) and DD/MM/YYYY (UK/EU).
- Business Days / Working Days
- Days when businesses are typically open — Monday through Friday, excluding public holidays. Many contractual and legal deadlines are expressed in business days rather than calendar days.
- Unix Timestamp
- The number of seconds since 00:00:00 UTC on January 1, 1970 (the Unix epoch). Used extensively in computing. January 1, 2025 00:00:00 UTC = Unix timestamp 1,735,689,600.
Frequently Asked Questions
How do I calculate the exact number of days between two dates?
Subtract the earlier date from the later date. Most calculation tools count the days between but don't include both endpoints — if counting an event's duration that starts and ends on specific days, you may want to add 1. January 1 to December 31 is 364 days apart but spans 365 calendar days including both endpoints.
How do I calculate someone's exact age?
Age = Years since birthdate, with the birthday month and day determining the completion of each year. Someone born March 15, 1990, on June 1, 2025 is 35 years old (turned 35 on March 15, 2025). The age calculator shows years, months, and days for precision.
What time is it in New York / Los Angeles / Sydney when it's noon in London?
Noon London (GMT/UTC in winter, BST/UTC+1 in summer): New York = 7:00 AM EST (5 hours behind) or 8:00 AM EDT in summer; Los Angeles = 4:00 AM PST (8 hours behind) or 5:00 AM PDT; Sydney = 11:00 PM AEDT (11 hours ahead in summer) or 9:00 PM AEST (9 hours ahead). Daylight saving time changes these offsets — always verify current local time.
How many working days are there in a year?
In a standard year with 52 full weeks: 52 × 5 = 260 working days. Subtract public holidays: UK has 8 bank holidays (England & Wales) → approximately 252 working days. US has 10 federal holidays → approximately 250 working days. Actual number varies by year and which days bank holidays fall on.