London is UTC+0 (GMT) / UTC+1 (GMT+1). Los Angeles is UTC−7 (PDT) / UTC−8 (PST). Los Angeles is currently 8 hours behind London.
There is no overlap of standard business hours (09:00–17:00) between these two cities. Consider early morning or late afternoon calls where one side works slightly outside core hours.
Times shown in London local time → Los Angeles local time. Based on business hours 09:00–17:00.
London operates on Greenwich Mean Time (GMT, UTC+0) in winter and British Summer Time (BST, UTC+1) from late March to late October. The city sits at the Prime Meridian — longitude 0° — established at the Royal Observatory in Greenwich in 1884 when the International Meridian Conference adopted Greenwich as the world's reference point for time and longitude. The GMT standard was already in widespread use because of Britain's dominance in maritime navigation and the railway network, which demanded a single national time to replace the patchwork of local times that differed by minutes from town to town.
The UK introduced Daylight Saving Time during World War I in 1916, following Germany's lead, to reduce coal consumption by extending evening daylight. Today DST is governed by EU rules (retained in UK law post-Brexit), meaning the clocks change on the last Sunday of March and October. London is one of the world's most important financial centres: the London Stock Exchange opens at 08:00 GMT and closes at 16:30, overlapping with Asian market closes in the morning and US market opens in the afternoon — a position that helps make London the largest foreign-exchange trading centre on earth.
Because London is UTC+0 in winter, it serves as a natural reference point for international scheduling. A meeting at "noon UTC" is noon in London from November to March. The city is 5 hours ahead of New York (EST) in winter and 8 hours behind Tokyo (JST), making it the pivot of East–West business communication.
Los Angeles observes Pacific Time: UTC−8 (PST, Pacific Standard Time) in winter and UTC−7 (PDT, Pacific Daylight Time) during DST, which runs from the second Sunday in March to the first Sunday in November. The Pacific Time Zone covers the US West Coast, British Columbia in Canada, and parts of Mexico. Los Angeles is 3 hours behind New York, 8 hours behind London (winter), and 17 hours behind Tokyo — the largest offset between any two major business hubs, making real-time collaboration between LA and Tokyo exceptionally difficult.
California's economy is the fifth largest in the world by GDP, and Los Angeles is its entertainment and technology hub. The entertainment industry's standard workday is broadly 10:00–18:00 PT — slightly later than the East Coast norm — a schedule partly shaped by the city's car culture and long commutes. Silicon Valley, though technically in the San Francisco Bay Area (same timezone), has contributed to a global culture of asynchronous work that somewhat eases the burden of Pacific–European collaboration.
California voters approved Proposition 7 in 2018, which would allow the state legislature to enact year-round DST, but federal law changes are required before the state could actually stop changing its clocks. Until then, LA changes on the same schedule as the rest of the continental US. The Pacific–Eastern 3-hour gap means that Wall Street has been open for three hours by the time most Angelenos start their workday — a feature, not a bug, for West Coast traders who read overnight news before the market opens.
Los Angeles is currently 8 hours behind London.
When it is 12:00 noon in London, it is 04:00 in Los Angeles (based on current offsets — verify during DST transitions).
London observes DST, changing from GMT to GMT+1. Los Angeles observes DST, changing from PDT to PST.