World Clock Calculator
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Formula
Target Time = Source Time + (Target UTC Offset - Source UTC Offset)
To convert between time zones, add the difference between the target and source UTC offsets to the source time. If the result exceeds 24 hours, add one day. If it falls below 0, subtract one day.
Worked Examples
Example 1: US-Europe Business Call
Problem: A team in New York wants to schedule a call with London colleagues at 2:00 PM New York time. What time is it in London?
Solution: New York is UTC-5, London is UTC+0\nTime difference = 0 - (-5) = +5 hours\n2:00 PM + 5 hours = 7:00 PM\n\nLondon is 5 hours ahead of New York.\nNote: During summer when both observe DST, the difference remains 5 hours since both shift by 1 hour.
Result: 2:00 PM in New York = 7:00 PM in London (5 hours ahead)
Example 2: US-Japan Coordination
Problem: A developer in Los Angeles needs to join a 10:00 AM meeting in Tokyo. What time must they wake up?
Solution: Los Angeles is UTC-8, Tokyo is UTC+9\nTime difference = 9 - (-8) = +17 hours\n10:00 AM Tokyo - 17 hours = 5:00 PM previous day LA time\n\nAlternatively: Tokyo is 17 hours ahead of LA.\nSo 10 AM Tuesday in Tokyo = 5 PM Monday in LA.
Result: 10:00 AM Tokyo = 5:00 PM previous day in Los Angeles (17 hours behind)
Frequently Asked Questions
How do time zones work around the world?
Time zones divide the Earth into 24 regions, each nominally spanning 15 degrees of longitude, corresponding to one hour of time difference. The system is based on Coordinated Universal Time (UTC), formerly Greenwich Mean Time (GMT), centered on the Prime Meridian at Greenwich, London. Moving east from Greenwich, time zones are ahead (UTC+1, UTC+2, etc.), and moving west they are behind (UTC-1, UTC-2, etc.). However, actual time zone boundaries follow political and geographical borders rather than strict longitude lines, which is why some countries and regions have unusual offsets. India uses a single time zone of UTC+5:30 despite spanning about 30 degrees of longitude.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.
Is World Clock Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.
How accurate are the results from World Clock Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.