Free time zone calculator
Convert a time from one time zone to another in a click — this time zone converter works straight from UTC offsets, so you enter a time, the offset you are converting from, and the offset you are converting to, and it shows the matching clock time, updated live, as you type.
On this page13 sections
Date calculations use calendar days. Working days exclude weekends but not public holidays unless noted.
Results are estimates. Consult a professional.
What is a time zone converter?
A time zone converter takes a clock time in one time zone and tells you the matching clock time in another. This time zone calculator works from UTC offsets — the number of hours a zone runs ahead of or behind Coordinated Universal Time (UTC) — so you enter a time, the offset you are converting from, and the offset you are converting to, and it shows the result instantly.
Offsets are written relative to UTC: UTC+0 is the reference (the same clock as GMT), positive offsets are zones east of it (UTC+1 in central Europe, UTC+9 in Japan), and negative offsets are zones west of it (UTC−5 for US Eastern Standard Time, UTC−8 for US Pacific Standard Time). Convert a time between any two offsets and you have answered questions like "what time is 2 PM Eastern in London?" without counting on your fingers.
How to convert a time between two UTC offsets
Converting between two zones is a single subtraction followed by adding the difference to the clock. You do not need to route through UTC by hand — the gap between the two offsets is all that matters:
- Find the offset difference: subtract the from-offset from the to-offset.
- Add that difference to the original time (a negative difference moves the clock earlier; a positive one moves it later).
- Wrap into a 24-hour clock if the result lands below 00:00 or at/above 24:00 — add or subtract 24 hours so the time reads between 00:00 and 23:59.
Because only the difference between the offsets counts, converting 12:00 from UTC+0 to UTC−5 gives the same shift as converting from UTC+2 to UTC−3 — both move the clock back 5 hours. That is why you can ignore UTC itself once you know each zone's offset.
A worked example with the time zone converter
Maya has a call listed as 12:00 UTC and needs the New York start time during standard time, when US Eastern is UTC−5. This is the converter's default state, so it is the exact screen she sees on opening the tool.
Step 1 — Enter the known time and both offsets
Time = 12:00, From UTC offset = 0, To UTC offset = −5. The from-zone is UTC/GMT and the to-zone is US Eastern Standard Time.
Step 2 — Take the offset difference
Difference = to − from = (−5) − 0 = −5 hours. New York is 5 hours behind UTC, so the clock moves 5 hours earlier.
Step 3 — Apply the shift and read the result
12:00 − 5:00 = 07:00. The result stays inside the 24-hour clock, so no day wrap is needed. The converter shows 07:00 and the note "12:00 at UTC+0 becomes 07:00 at UTC-5."
UTC offsets for common time zones (EST, PST, GMT and more)
The offsets below are the values you type into the converter. They are standard-time offsets; during daylight saving time many of them shift by one hour (see the next section). Fractional offsets like India's UTC+5:30 are entered as 5.5, and the few 45-minute zones (Nepal UTC+5:45) as 5.75.
| Zone | Abbreviation | Standard offset | Enter as |
|---|---|---|---|
| Coordinated Universal Time / Greenwich Mean Time | UTC / GMT | UTC+0 | 0 |
| US Pacific Standard Time | PST | UTC−8 | -8 |
| US Mountain Standard Time | MST | UTC−7 | -7 |
| US Central Standard Time | CST | UTC−6 | -6 |
| US Eastern Standard Time | EST | UTC−5 | -5 |
| Central European Time | CET | UTC+1 | 1 |
| Eastern European Time | EET | UTC+2 | 2 |
| India Standard Time | IST | UTC+5:30 | 5.5 |
| China Standard Time | CST (China) | UTC+8 | 8 |
| Japan Standard Time | JST | UTC+9 | 9 |
| Australian Eastern Standard Time | AEST | UTC+10 | 10 |
Standard-time offsets. Note CST is ambiguous — US Central (UTC−6) and China (UTC+8) share the abbreviation — so always convert by the numeric offset, not the letters.
Daylight saving time: enter the offset that is in effect
This converter uses the fixed numeric offsets you type — it does not know the date, so it cannot tell whether daylight saving time (DST) is active. During DST a zone's offset moves one hour closer to (or further from) UTC, and you must enter the offset that applies on your date.
- US Eastern: UTC−5 in winter (EST) but UTC−4 in summer (EDT). Enter −5 or −4 depending on the date.
- US Pacific: UTC−8 in winter (PST) but UTC−7 in summer (PDT).
- UK: UTC+0 in winter (GMT) but UTC+1 in summer (BST).
- Central Europe: UTC+1 in winter (CET) but UTC+2 in summer (CEST).
When the answer lands on the next or previous day
Large offset gaps can push the converted time past midnight. The converter wraps the result back into a single 24-hour clock, so it always shows a valid HH:MM — but it shows the clock time only and does not label a day change. Reading the day shift is yours to infer from the size and sign of the offset difference.
Difference = 9 − 0 = +9 hours. 23:00 + 9:00 = 32:00, which is past midnight; subtracting 24 hours wraps it to 08:00. The converter displays 08:00 — and because you added 9 hours and crossed midnight, you can read that as 08:00 the next day in Tokyo.
The rule of thumb: if you add hours and pass 24:00, the answer is the next day; if you subtract hours and drop below 00:00, it is the previous day. The clock time the tool shows is correct either way — only the calendar date is left for you to add.
Using it to plan meetings across time zones
The most common reason to convert a time is scheduling a call that spans zones. Pick the meeting time in your own zone, set From to your offset and To to each attendee's offset, and read off their local start time — repeating for every region on the invite.
From UTC+0 to UTC−5 (New York) gives 07:00; to UTC+1 (London on summer time, or central Europe) gives 13:00; to UTC+5.5 (India, IST) gives 17:30. One UTC anchor, three local clock times — and you can see at a glance that 07:00 is early for New York.
For payroll or timesheet work where you need decimal hours rather than a converted clock, use the time to decimal calculator; to read or write times in 24-hour form, see the military time converter.
Common time zone conversion questions
How do I convert EST to GMT?
Enter the EST time, set From to −5 and To to 0. The difference is 0 − (−5) = +5 hours, so the converter adds 5 hours: 09:00 EST becomes 14:00 GMT. During US summer time, Eastern is EDT (−4), so use −4 instead.
Does this converter handle daylight saving time automatically?
No. It uses the fixed numeric offsets you type and has no date awareness, so you enter the offset that is in effect on your date — for example −5 for EST in winter or −4 for EDT in summer. That keeps the result deterministic and lets you convert historical or future times too.
How do I enter a half-hour or 45-minute time zone?
Use a decimal offset: India (UTC+5:30) is 5.5, Nepal (UTC+5:45) is 5.75, and the Marquesas (UTC−9:30) is -9.5. The converter accepts decimals and applies the exact minute shift.
How this calculator works and sources
This time zone converter computes new = old + (toOffset − fromOffset) and wraps the result into a single 24-hour clock. It uses the fixed UTC offsets you enter — it does not look up cities, dates, or daylight saving rules — so it is fully deterministic and runs entirely in your browser. UTC offsets, the UTC↔GMT equivalence, and DST behaviour below are standard, well-documented timekeeping facts.
Wikipedia — List of UTC offsets (standard offsets for every time zone, including fractional zones).timeanddate.com — UTC time and the UTC↔GMT relationship.Wikipedia — UTC offset (how offsets are written and how daylight saving shifts them).Frequently asked questions about the free time zone calculator
About this time zone converter
This time zone converter runs entirely in your browser. It computes new = old + (toOffset - fromOffset) and wraps the answer into a single 24-hour clock, using the fixed UTC offsets you enter - it does not look up cities, dates, or daylight saving rules, so the result is fully deterministic and nothing you type is sent anywhere.
Find more tools on the everyday calculators shelf, or browse the full calculators directory. Related time tools include the military time converter and the time to decimal calculator.