Guam is 17 to 18 hours ahead of San Diego, depending on the time of year. If you are both awake 7 am to 11 pm, a January weekday gives you 10 hours awake at the same time, though none of them is outside a 9-to-5 for both of you (in July: 9 hours shared, 0 hours free). Here are the good ones.
Guam is 18 hours ahead of San Diego that week. On a weekday you are both awake for 10 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 Diego time, with each zone’s own daylight-saving rules for those dates. Guam awake 7 am – 11 pm, working 9 am – 5 pm weekdays; San Diego awake 7 am – 11 pm, working 9 am – 5 pm weekdays.
A weekday, in San Diego timeboth awake
San Diegoawake 7 am – 11 pm
Guamawake 1 pm – 5 am San Diego time
7a10a1p4p7p10p1a4a7a
Best on a weekday
6 – 8 pm San Diego
noon – 2 pm Guam · San Diego early evening, Guam lunchtime (their next day) · during Guam’s lunch break
Another weekday option
1 – 3 pm San Diego
7 – 9 am Guam · San Diego lunchtime, Guam morning (their next day) · during San Diego’s work hours
The long weekend call
Sat 6 – 9 pm San Diego
Sun noon – 3 pm Guam · San Diego early evening, Guam lunchtime
The week · San Diego time, 11 Jan – 17 Jan
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
5p
6p
7p
8p
9p
10p
Mon
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
Tue
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
Wed
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
Thu
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
Fri
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
Sat
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
Sun
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
Columns are San Diego hours; the small figure in each cell is the time in Guam. both freeboth awake, one at workGuam asleep
The Guam–San Diego gap through 2027
Dates
Difference
1 January – 13 March
Guam is 18 hours ahead of San Diego
14 March – 6 November
Guam is 17 hours ahead of San Diego
7 November – 31 December
Guam is 18 hours ahead of San Diego
The week grid and call windows were worked out for 11 Jan to 17 Jan 2027 with the IANA time-zone rules for Pacific/Guam (Guam) and America/Los_Angeles (San Diego). That week San Diego is on standard time and Guam 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 Diego
In San Diego
Guam, January
Guam, July
7 am
1 am (next day)
midnight (next day)
9 am
3 am (next day)
2 am (next day)
11 am
5 am (next day)
4 am (next day)
1 pm
7 am (next day)
6 am (next day)
3 pm
9 am (next day)
8 am (next day)
5 pm
11 am (next day)
10 am (next day)
7 pm
1 pm (next day)
noon (next day)
9 pm
3 pm (next day)
2 pm (next day)
Wednesday times. Send times as “your 8 pm” or “my 8 pm” so nobody has to guess whose clock you mean.
If one of you is deployed or stationed in Guam
Duty days rarely follow nine to five. Set the work hours on the Guam side to “No fixed work hours” and read the grid as a map of who is likely awake, not a promise of who is free. Calls may depend on access and schedules you cannot see from home, so keep the windows above as a starting point rather than a plan.
Follow your unit’s guidance on what you share about times, places and movements. The deployment countdown has a private mode that hides every date, and the deployment countdown guide covers OPSEC habits for families.
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 Guam 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 Guam and San Diego?
Guam is 17 to 18 hours ahead of San Diego, depending on the time of year. In 2027 it is 18 hours from 1 January to 13 March and from 7 November to 31 December; 17 hours from 14 March to 6 November.
What is the best time to call Guam from San Diego?
In January, the easiest two hours on a weekday are 6 – 8 pm San Diego, which is noon – 2 pm Guam: San Diego early evening, Guam lunchtime, the next day there, during Guam’s lunch break. At the weekend, Sat 6 – 9 pm San Diego (Sun noon – 3 pm Guam) 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 Guam and San Diego share?
If both of you are awake from 7 am to 11 pm, you share 10 hours on a January weekday, but none of them falls outside 9-to-5 working hours in both places; in July it is 9 hours shared and 0 hours free.
Does daylight saving time change the call times?
Yes. In 2027 San Diego changes its clocks on 14 March and 7 November and Guam does not change its clocks, so a call you keep at the same time in San Diego moves by an hour in Guam on those dates. Check the table on this page and agree the new time out loud after each change.