Use this time zone and date calculator to compare current times across cities or find the number of days between two dates.
World Clock
Date Difference Calculator
Difference: —
Two Tools in One: World Clock and Date Calculator
This page combines a live world clock with a date difference calculator, so you can check the current time in another city and work out how many days sit between two dates without opening two separate tools.
How to Use
- The World Clock updates automatically, no input needed.
- The Date Difference Calculator lets you pick two dates and see the days and weeks between them.
Example (world clock): to find the time difference between Los Angeles and Tokyo, check both cities in the list above. Tokyo runs 17 hours ahead of Los Angeles, so 9am in Los Angeles is 2am the next day in Tokyo.
Example (date difference): pick January 1 and March 15 in the same year, and the calculator returns 73 day(s) (10.4 weeks).
Common Time Zone Offsets (From UTC)
Standard-time offsets for the cities shown in the World Clock above (some observe daylight saving, which shifts these by an hour part of the year). To find the time difference between any two cities here, subtract one offset from the other: Tokyo (UTC+9) minus Los Angeles (UTC-8) is 17 hours.
| City | Standard UTC Offset |
|---|---|
| Los Angeles | UTC-8 |
| Denver | UTC-7 |
| Chicago | UTC-6 |
| New York | UTC-5 |
| London | UTC+0 |
| Paris | UTC+1 |
| Tokyo | UTC+9 |
| Sydney | UTC+10 |
Did You Know?
Time zones didn’t exist until 1883. Before then, every town set its clocks by local solar noon, which worked fine until railroads made it possible to travel faster than the sun’s apparent movement across the sky. Canadian railway engineer Sandford Fleming, prompted by missing a train connection in 1876 over a time mix-up, proposed worldwide standard time zones. American and Canadian railroads adopted four zones in 1883, and the International Prime Meridian Conference made the system official in 1884 (source).
Frequently Asked Questions
How do I calculate the time difference between two time zones?
Find both cities in the UTC offset table above and subtract one offset from the other. For example, New York (UTC-5) to London (UTC+0) is a 5-hour difference, and New York to Tokyo (UTC+9) is 14 hours.
Does the World Clock account for daylight saving time?
Yes. It reads your browser’s built-in time zone database, which automatically adjusts for daylight saving in each city shown.
Does the date difference include both start and end days?
The calculator counts the full days between the two dates, not the number of calendar days touched. January 1 to January 3 returns 2 days, since that’s the span between them.
Why do some countries not use daylight saving time?
Regions near the equator see little seasonal daylight change, so shifting clocks offers no benefit. Other countries have simply chosen to opt out for practical or political reasons.