Best Time to Call

Timezone maths is the kind of thing your brain refuses to do properly at 11pm when you're trying to work out if it's too late to ring your mate in Vancouver. This calculator does it for you in about three seconds.

A real example

You're in Melbourne (AEDT, UTC+11 in summer). Your sister lives in London (GMT, UTC+0). You're both awake from 8am to 10pm local time.

The overlap? Roughly 8pm to 10pm your time, which is 9am to 11am her time. That's a two-hour window. Miss it and you're either waking her up or catching her mid-dinner.

Throw in a third timezone and it gets worse. If your parents are in Dubai (UTC+4), the three-way overlap shrinks to about 90 minutes. That's the kind of thing you'd burn 20 minutes Googling, or you could type it in here.

Getting the most out of this

Adjust the waking hours to match real schedules, not defaults. If your contact works nights and sleeps until noon, put that in. The overlap shifts completely.

Try different days if daylight saving has recently changed. Australia and the UK shift clocks at different times of year, so your window might be an hour longer or shorter than last month.

Bookmark the result. Timezone differences don't change often, so once you've found the window, it'll stay the same for months.

Frequently asked questions

Does this account for daylight saving?

It uses your device's timezone database, which includes DST transitions. If your phone or laptop knows it's daylight saving where you are, the calculator picks that up automatically.

What if someone works odd hours?

Change the waking hours to whatever fits. Set 10pm to 6am for a night-shift worker and the overlap adjusts to match. There's no requirement to use the default 8am to 10pm range.

Why is my overlap window so small?

Big timezone gaps eat into shared hours fast. Melbourne to Los Angeles is a 17 or 18 hour difference depending on the time of year. Two people who both sleep normal hours will share maybe a one-hour sliver in the early morning or late evening. Sometimes there's genuinely no good time, and the calculator will tell you that too.