Best time to call: time zone overlap calculator
Pick where you are and where you are calling. See the time difference and the hours when you can both pick up the phone.
Checking the clocks…
Uses today's clock changes. To see the time at a specific US or UK area code, open its area code page.
How it works
Choose the two time zones and set the hours each side is available. The calculator converts the other side's business day into your time using today's clock changes, then highlights the hours that overlap. The strip shows your whole day in half-hour blocks so you can see how much room there is.
Daylight saving catches people out
The US and the UK change their clocks on different dates. The US moves on the second Sunday of March and the first Sunday of November, while the UK moves on the last Sunday of March and October. For a few weeks twice a year the gap between London and New York is four hours instead of five. Arizona does not change its clocks at all. The tool uses today's date, so check again after a clock change.
Tips for calling across time zones
- Between the UK and the US East Coast the usual window is the US morning, which is the UK afternoon.
- Asia to the US needs one side to call early or late, so it is often better to book a time than to cold dial.
- Avoid the first and last hour of their day, and their lunch hour, where you can.
Want the time at a particular number? Each area code page shows the live local time.
FAQ
What are normal business hours in the US and UK?
Most offices run roughly 9:00 to 17:00 local time, Monday to Friday, and UK offices often finish at 17:30. Shops and services keep longer hours, so adjust the settings to match who you are calling.
How many hours behind is the US from the UK?
Normally 5 hours for Eastern time, 6 for Central, 7 for Mountain and 8 for Pacific. The gap shrinks by one hour for a few weeks in March and in October to November, when the two countries change their clocks on different dates.
Does it know about weekends and public holidays?
No. It only compares clock times, so check weekends and public holidays yourself before booking a call.