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Time Zone Offset Calculator

Enter a time and the source and target UTC offsets to convert it.

How it is calculated

The tool works on UTC offsets, not on named zones. It turns the time into minutes after midnight, adds the offset difference, and wraps the total round a 24-hour day: delta = (to − from) × 60 minutes, raw = H × 60 + M + delta, result = raw mod 1440, day shift = floor(raw / 1440). A shift of 0 shows as “same day”, +1 as the next day and −1 as the previous day; a larger gap, such as UTC−12 to UTC+14, can give +2 days. The time must be written HH:MM on a 24-hour clock (9:05 is fine, 24:00 and 2:30 PM are not). Offsets are in hours and may be fractional, written with a decimal point: 5.5 for UTC+5:30, 5.75 for UTC+5:45. The offset difference is shown with two decimals. Daylight saving is not applied, so enter the offset that is in force on the date.

Worked example

It is 22:30 at UTC−5 and you want the time at UTC+1. The offset difference is 1 − (−5) = 6 hours = 360 minutes. The time is 22 × 60 + 30 = 1350 minutes after midnight. Add: 1350 + 360 = 1710. Since 1710 is more than 1440, subtract one day: 1710 − 1440 = 270 minutes, which is 4 hours 30 minutes. The tool shows 04:30, +1 day (the next calendar day), with an offset difference of 6.00 h.

Try this example →

Common mistakes

  • Subtracting in the wrong direction. The shift is target minus source, so going from UTC−5 to UTC+1 adds 6 hours; subtracting would give 16:30 instead of 04:30.
  • Entering a named zone (like “EST”) or a clock time with AM/PM. Only numeric offsets and a 24-hour HH:MM time are read, and 2:30 PM returns nothing.
  • Writing a half-hour offset as 5:30. Use 5.5, with a decimal point; for UTC+5:45 use 5.75. A decimal comma such as 5,5 is not read.
  • Ignoring the day change. A result like 04:30 on its own looks like the same morning; the “+1 day” line tells you it is the next calendar date.
  • Using the standard offset in summer, or the other way round. A zone's offset changes with daylight saving, and the tool will not adjust it for you.

About this calculator

Converting a time between UTC offsets means adding or subtracting the difference between the two offsets — for example, moving a time from UTC-5 (New York) to UTC+1 (Paris) means adding 6 hours. The tricky part isn't the math itself but tracking whether that shift pushes the clock time past midnight, landing the result on the next calendar day, or pulls it back past midnight onto the previous day.

This calculator handles both the offset math and the day-rollover logic in one step, which is genuinely useful for scheduling international meetings, coordinating remote teams, or working out flight arrival times across time zones — situations where “just add the hours” quietly gets the date wrong if you're not careful near midnight.

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Comments (1)

  • Editorial team

    Offsets change with daylight saving, and the two sides rarely switch on the same weekend: much of the US and much of Europe move their clocks on different dates, so a gap you know can be an hour off for a couple of weeks a year. Enter the offsets that apply on the actual date, such as 5.5 for India. The tool works on offsets, not names. Which two regions do you convert between most?

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