Which zone this page means. Japan does not observe daylight saving, so JST applies all year. BST means British Summer Time (UTC+1) and also Bangladesh Standard Time (UTC+6). This page means the British zone, which applies from the last Sunday in March to the last Sunday in October; the rest of the year the United Kingdom is on GMT.
JST is ahead of BST by 8 hours today
On 19 August 2026, Japan Standard Time is on JST at UTC+09:00 and British Summer Time is on BST at UTC+01:00. The gap between them is 8 hours, with BST behind. So 9:00 am in JST is 1:00 am in BST, and 5:00 pm in JST is 9:00 am in BST. Going the other way, see BST to JST.
The gap is not constant, and that is the part that catches people out
British Summer Time is currently observing daylight saving and changes next on 25 October 2026. Japan Standard Time does not observe daylight saving, so the gap moves only when British Summer Time changes its clocks — twice a year, by one hour.
When you can actually both be at work
Taking a working day as 9:00 am to 5:00 pm local at each end, there are 0 overlapping hours in a normal day. There is none: the two working days do not touch at all, so any live meeting between Japan Standard Time and British Summer Time has to sit outside somebody's normal hours. The table above shows which end has the shorter stretch to give up.
Zone rules are set by legislation and change, sometimes at short notice. This page is built against tzdata 2026a, last reviewed 2026-08-18. Quarterly. Zone rules change by legislation, sometimes at short notice. Version and review date are shown on every zone page. The converter above reads your browser's own copy of the zone database, so if a rule has changed since this page was built the live answer follows the new rule.
Every convention used above — whether the start date counts, how month ends are clamped, which holidays close an office — is written out on the methodology page, including the daylight-saving rules behind the 8-hour gap above.