Time Zone Calculator
Instantly convert the time between major world cities, see each city's UTC offset and daylight saving status, and check who's awake right now on a live world clock.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
New York
11:56 PM, Wednesday, August 19, 2026
UTC-04:00 (DST)
London
4:56 AM, Thursday, August 20, 2026
UTC+01:00 (DST)
Summary
When it's 11:56 PM in New York, it's 4:56 AM in London on Thursday, August 20 — London is 5 hours ahead of New York.
Time Difference
London is 5 hours ahead of New York
World clock right now (highlighted bars are your selected cities)
What is a Time Zone Calculator?
A time zone calculator converts the current (or any specific) time in one city to the equivalent local time in another, accounting for both the fixed UTC offset each region uses and whether either city is currently observing daylight saving time. It's the tool behind everyday questions like scheduling a call across continents, or figuring out what time a flight actually lands in local time.
This calculator supports 25 major world cities, shows each one's current UTC offset and daylight saving status, and includes a live world clock chart so you can see at a glance which cities are in their daytime or nighttime hours right now.
How Time Zone Conversion Works
Every time zone is defined as a fixed offset from Coordinated Universal Time (UTC) — for example, UTC−05:00 for U.S. Eastern Time in winter. To convert between two cities, this calculator finds the exact UTC instant that corresponds to the "From" city's local time, then re-expresses that same UTC instant using the "To" city's offset:
This automatically accounts for cities using half-hour or 45-minute offsets (like India at UTC+05:30), and for whichever city — one, both, or neither — is currently observing daylight saving time.
Daylight Saving Time Complicates the Math
Because not every country observes daylight saving time, and those that do don't switch on the same dates, the hour difference between two cities can actually change twice a year. New York and London, for instance, are usually 5 hours apart, but briefly become 4 hours apart for a couple of weeks each spring and fall when their DST transitions don't align.
Fixed vs. Half-Hour Offsets
Most of the world uses whole-hour UTC offsets, but several countries deliberately use a half-hour or 45-minute offset instead — India (UTC+5:30), and parts of Australia and Iran among them. These offsets are usually chosen so the region's solar noon lines up better with clock noon than a whole-hour offset would allow.
Example — Your Current Selection
When it's 11:56 PM in New York, it's 4:56 AM in London on Thursday, August 20 — London is 5 hours ahead of New York.
Additional Example — Scheduling Across Three Continents
A team split between New York, London, and Singapore trying to find a shared meeting slot needs to account for all three offsets at once: when it's 9:00 AM in New York, it's 2:00 PM in London and 10:00 PM in Singapore — meaning a "normal business hours" call for the U.S. and U.K. team falls squarely in Singapore's late evening, illustrating why globally distributed teams often rotate which region takes the inconvenient time slot.
About These Parameters
- From City & To City
- The two cities you're converting between. Each city's current UTC offset and daylight saving status is looked up automatically for the date you're converting.
- Date & Time
- Optional — leave it blank to convert the current moment. Enter a specific date and time (interpreted in the From City's local time) to check a future meeting, flight, or event, including whether daylight saving time applies on that date.
Frequently Asked Questions
Does this account for daylight saving time automatically?
Yes — each city's offset is calculated for the specific date being converted, so the result correctly reflects whichever cities are observing daylight saving time on that date.
Can I convert a date in the past or future, not just right now?
Yes — use the optional Date & Time field to convert any specific moment, entered in the From City's local time. This is especially useful for checking whether a future meeting falls before or after a daylight saving time change.
Why is the time difference sometimes not a whole number of hours?
Some regions — India, parts of Australia, and Iran among them — use a half-hour or 45-minute UTC offset rather than a whole hour, so converting to or from those cities can produce a fractional hour difference like 3.5 or 9.5 hours.
What does the world clock chart show?
It plots the current local hour (0-24) in a dozen major cities around the world at the same instant, so you can see who's in daytime and who's asleep right now relative to your selected cities, which are highlighted.