Tokyo is 16 to 17 hours ahead of San Francisco, depending on the time of year. If you are both awake 7 am to 11 pm, a January weekday gives you 9 hours awake at the same time, though none of them is outside a 9-to-5 for both of you (in July: 8 hours shared, 0 hours free). Here are the good ones.
Tokyo is 17 hours ahead of San Francisco that week. On a weekday you are both awake for 9 hours, but none of them is outside work for both of you, so a lunch break or a commute has to do the work.
Worked out for the week of 11 January 2027 (11 Jan – 17 Jan), in San Francisco time, with each zone’s own daylight-saving rules for those dates. Tokyo awake 7 am – 11 pm, working 9 am – 5 pm weekdays; San Francisco awake 7 am – 11 pm, working 9 am – 5 pm weekdays.
A weekday, in San Francisco timeboth awake
San Franciscoawake 7 am – 11 pm
Tokyoawake 2 pm – 6 am San Francisco time
7a10a1p4p7p10p1a4a7a
Best on a weekday
7 – 9 pm San Francisco
noon – 2 pm Tokyo · San Francisco evening, Tokyo lunchtime (their next day) · during Tokyo’s lunch break
Another weekday option
2 – 4 pm San Francisco
7 – 9 am Tokyo · San Francisco afternoon, Tokyo morning (their next day) · during San Francisco’s work hours
The long weekend call
Sat 6 – 9 pm San Francisco
Sun 11 am – 2 pm Tokyo · San Francisco early evening, Tokyo lunchtime
The week · San Francisco time, 11 Jan – 17 Jan
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
5p
6p
7p
8p
9p
10p
Mon
12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
Tue
12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
Wed
12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
Thu
12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
Fri
12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
Sat
12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
Sun
12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
Columns are San Francisco hours; the small figure in each cell is the time in Tokyo. both freeboth awake, one at workTokyo asleep
The Tokyo–San Francisco gap through 2027
Dates
Difference
1 January – 13 March
Tokyo is 17 hours ahead of San Francisco
14 March – 6 November
Tokyo is 16 hours ahead of San Francisco
7 November – 31 December
Tokyo is 17 hours ahead of San Francisco
The week grid and call windows were worked out for 11 Jan to 17 Jan 2027 with the IANA time-zone rules for Asia/Tokyo (Tokyo) and America/Los_Angeles (San Francisco). That week San Francisco is on standard time and Tokyo keeps the same time all year. The table uses the same rules for every day of 2027. The finder above recalculates for the current week in your browser.
When it is … in San Francisco
In San Francisco
Tokyo, January
Tokyo, July
7 am
midnight (next day)
11 pm
9 am
2 am (next day)
1 am (next day)
11 am
4 am (next day)
3 am (next day)
1 pm
6 am (next day)
5 am (next day)
3 pm
8 am (next day)
7 am (next day)
5 pm
10 am (next day)
9 am (next day)
7 pm
noon (next day)
11 am (next day)
9 pm
2 pm (next day)
1 pm (next day)
Wednesday times. Send times as “your 8 pm” or “my 8 pm” so nobody has to guess whose clock you mean.
Stop doing the math every day
The Long Goodbye keeps your person’s local time and time of day on your home-screen widget and lock screen, so you can see whether it is morning coffee or midnight in Tokyo before you call. A “thinking of you” tap lights up their widget, and a countdown keeps the next visit in view.
What is the time difference between Tokyo and San Francisco?
Tokyo is 16 to 17 hours ahead of San Francisco, depending on the time of year. In 2027 it is 17 hours from 1 January to 13 March and from 7 November to 31 December; 16 hours from 14 March to 6 November.
What is the best time to call Tokyo from San Francisco?
In January, the easiest two hours on a weekday are 7 – 9 pm San Francisco, which is noon – 2 pm Tokyo: San Francisco evening, Tokyo lunchtime, the next day there, during Tokyo’s lunch break. At the weekend, Sat 6 – 9 pm San Francisco (Sun 11 am – 2 pm Tokyo) gives you a longer call. Change the awake and work hours in the finder on this page to fit your own days.
How many waking hours do Tokyo and San Francisco share?
If both of you are awake from 7 am to 11 pm, you share 9 hours on a January weekday, but none of them falls outside 9-to-5 working hours in both places; in July it is 8 hours shared and 0 hours free.
Does daylight saving time change the call times?
Yes. In 2027 San Francisco changes its clocks on 14 March and 7 November and Tokyo does not change its clocks, so a call you keep at the same time in San Francisco moves by an hour in Tokyo on those dates. Check the table on this page and agree the new time out loud after each change.