Answer first
What this calculator tells you
Convert a time between two time zones, with a setting for daylight saving in each. Schedule a call across zones without guessing which side of midnight it lands on. Formula: Local time at the destination = time − (origin offset + origin daylight saving) + (destination offset + destination daylight saving). At the worked-example inputs, the time at the destination is 5:00 PM. Holding every other input steady, moving time in the origin zone from 11:00 AM to 1:00 PM moves the result from 4:00 PM to 6:00 PM.
Transparent method
The formula
Schedule a call across zones without guessing which side of midnight it lands on.
Worked example
Example inputs
How to interpret the result
Two zones differ by a fixed number of hours, but daylight saving changes that gap for part of the year, and countries switch on different dates. Noon in New York in standard time is 5:00 PM in London in winter. In the weeks when only one side has moved its clocks, the gap is four hours, not five. The daylight saving setting for each zone is the piece people forget.
Times are worked out from the clock readings you enter, to the minute. Daylight saving, leap seconds and a workplace's own rounding or break rules apply only where a field asks for them, so confirm any pay, travel or scheduling decision against the official clock and your own policy.
Before you rely on it
What to check
Confirm each place's daylight saving status on the date itself. The switch dates differ, so a week in March or in late October can be off by an hour.
The common error
Where people go wrong with time zone calculator
Assuming the difference is the same all year. It changes twice a year, and some regions do not observe daylight saving at all.
Sensitivity evidence
How time in the origin zone changes the time at the destination
Holding every other input at the worked-example value, moving time in the origin zone from 11:00 AM to 1:00 PM moves the time at the destination from 4:00 PM to 6:00 PM: a spread of 120 minutes.
| Time in the origin zone | Time at the destination | Day shift (−1, 0 or +1) | Hours ahead of the origin |
|---|---|---|---|
| 11:00 AM | 4:00 PM | 0 | 5 |
| 11:30 AM | 4:30 PM | 0 | 5 |
| 12:00 PMworked example | 5:00 PM | 0 | 5 |
| 12:30 PM | 5:30 PM | 0 | 5 |
| 1:00 PM | 6:00 PM | 0 | 5 |
Step by step
The worked example, input by input
| Input | Value used | What it means |
|---|---|---|
| Time in the origin zone | 12:00 PM | Enter the time in the origin zone used in this calculation. |
| From zone (standard time) | US Eastern (UTC−5) | The offset from UTC in standard time. |
| Daylight saving in the origin zone | No | Choose Yes during the months that zone has moved its clocks forward. |
| To zone (standard time) | UTC or London (UTC+0) | The offset from UTC in standard time. |
| Daylight saving in the destination zone | No | Choose Yes during the months that zone has moved its clocks forward. |
| Time at the destination | 5:00 PM | |
| Day shift (−1, 0 or +1) | 0 | |
| Hours ahead of the origin | 5 | |
Inputs, definitions and assumptions
Time in the origin zone
Enter the time in the origin zone used in this calculation. The prefilled worked-example value is 12:00 PM.
From zone (standard time)
The offset from UTC in standard time. The prefilled worked-example value is US Eastern (UTC−5).
Daylight saving in the origin zone
Choose Yes during the months that zone has moved its clocks forward. The prefilled worked-example value is No.
To zone (standard time)
The offset from UTC in standard time. The prefilled worked-example value is UTC or London (UTC+0).
Daylight saving in the destination zone
Choose Yes during the months that zone has moved its clocks forward. The prefilled worked-example value is No.
How to use this calculator
- 1Verify the inputs. Gather time in the origin zone, from zone (standard time), daylight saving in the origin zone, to zone (standard time) and daylight saving in the destination zone from your own documents; the prefilled values are examples.
- 2Save a baseline. The worked example puts the time at the destination at 5:00 PM. Store your own version of it as Scenario A.
- 3Test one change. Change one assumption at a time so the driver stays visible.
- 4Check the boundary. Read the interpretation boundary above before acting on the result.
People also ask
Frequently asked questions
How do you calculate time zone?
Local time at the destination = time − (origin offset + origin daylight saving) + (destination offset + destination daylight saving). At the worked-example inputs the time at the destination is 5:00 PM.
What does the time zone result mean?
Schedule a call across zones without guessing which side of midnight it lands on.
How much does time in the origin zone change the time at the destination?
Holding every other input at the worked-example value, moving time in the origin zone from 11:00 AM to 1:00 PM moves the time at the destination from 4:00 PM to 6:00 PM, a spread of 120 minutes.
What are the limits of this time zone calculator?
Times are worked out from the clock readings you enter, to the minute. Daylight saving, leap seconds and a workplace's own rounding or break rules apply only where a field asks for them, so confirm any pay, travel or scheduling decision against the official clock and your own policy. The tables on this page test time in the origin zone only from 11:00 AM to 1:00 PM; a value outside that range is not tabulated here.
Does the calculator account for daylight saving time?
Only where a field asks for it. The time zone calculator has a daylight saving setting for each zone. The other tools work from the clock times you enter, so enter the local clock reading as it appears on the day.
What happens when a time range crosses midnight?
The tools add 24 hours when the end time is earlier than the start, so 10:00 PM to 6:00 AM is eight hours. Two identical times read as zero, not as a full day.
Why do payroll systems use decimal hours?
Multiplying a rate by 7.75 is simple, while multiplying by 7 hours 45 minutes is not. Decimal hours turn a clock duration into a plain number that a spreadsheet can total.
How do I handle unpaid breaks on a time card?
Subtract the break from the total span, as the time card calculator does. Some workplaces treat short rest breaks as paid, so check your policy before you deduct one.
Why do two time zone converters sometimes disagree?
Usually because one has applied daylight saving and the other has not. Regions change their clocks on different dates, so check the date you are converting for.
Sources and evidence
Free Calculators Online is independent and is not affiliated with or endorsed by the source organizations. Educational estimates only.