Boston vs London Time: Practical Comparison for Business and Travel

Understanding the Time Difference Between Boston and London

If you coordinate with colleagues, clients, or friends in London from Boston, or vice versa, getting the time right is critical. Boston operates on Eastern Time (ET), which is UTC-5 (EST) in winter and UTC-4 (EDT) in summer. London uses Greenwich Mean Time (GMT, UTC+0) in winter and British Summer Time (BST, UTC+1) in summer. The standard difference is 5 hours, with Boston behind London. However, because the two regions shift their clocks on different dates, the offset briefly becomes 4 hours for a few weeks each spring and fall. For the full details on Boston's time zone and its hISTory, visit our Boston Time Zone page.

Current Hour Offset

Today, the offset is either 4 or 5 hours depending on the time of year. The table below shows the typical situations:

As you can see, the 4-hour offset occurs only during transition windows lasting about two weeks each. For a deep dive into how daylight saving time affects Boston, see our Daylight Saving Time in Boston page.

Business Hours Overlap

The typical workday runs from 9:00 AM to 5:00 PM locally. Because Boston is behind London, the overlap of these hours is limited. When the offset is 5 hours, a 9 AM start in Boston is already 2 PM in London. The common overlap for scheduling meetings is usually 9 AM to 12 PM Boston (2 PM to 5 PM London) or 1 PM to 4 PM Boston (6 PM to 9 PM London) if your London team is willing to stay a bit later. The following table shows the overlapping business hours in each time zone for both offset scenarios:

During the 4-hour offset periods, the overlap shifts: 9 AM Boston = 1 PM London, so the window moves an hour earlier. To see typical business hours in Boston, check out Business Hours in Boston.

Best Meeting Times Across Both Cities

For a meeting that respects both sides, aim for 9:00 AM–11:00 AM Boston time, which is 2:00 PM–4:00 PM London time (5-hour offset) or 1:00 PM–3:00 PM London time (4-hour offset). This avoids early mornings in Boston and late evenings in London. If your London team is flexible, a 1:00 PM Boston start (6:00 PM London) might work, but it's often outside standard hours. Always double-check today's exact offset using the live clock on our homepage.

How DST Shifts Affect the Difference

The 4-hour offset windows occur because the United States and the United Kingdom change to and from daylight saving time on different dates. In spring, the US shifts to EDT on the second Sunday of March, while the UK shifts to BST on the last Sunday of March. That creates two to three weeks of 4-hour difference. In autumn, the UK switches back to GMT on the last Sunday of October, while US stays on EDT until the first Sunday of November, again creating about one week of 4-hour difference. Outside these windows, the offset is a steady 5 hours. For sunrise and sunset times that help visualize the day length in Boston, see our Sunrise and Sunset Times page.

Quick Reference Table for Overlap Hours

The table below summarizes the overlapping business hours for the two common offsets:

Use this to plan your calls and meetings. Remember that London is always ahead of Boston, so always schedule in Boston's local time to avoid confusion. For more common questions about Boston time, visit our Boston Time FAQ.