Help

Time Zone Guru shows the same moment in several places at once, so you can spot when people are likely free, even when daylight saving rules differ.

Quick start

1. Now (top row) shows the live clock in each city.
2. Add or remove cities with search and the chips. Defaults are your current location, London, and New York (duplicates of your zone are skipped).
3. Rows are hours of your local day; columns are each city’s wall time at that same moment.
4. The Good column (emoji + green) shows how many cities are awake.

How to read the schedule

• Now is always live wall time, independent of the selected date.
• Your location is the first column: hours of your local day, with a short zone label (e.g. GMT+1, EDT).
• Rows = hours of your local day on the chosen date.
• Columns = locations. Each cell is that city’s local time at the same absolute moment as your hour.
• +1 / −1 badges mean that city is already on the next or previous calendar day.

Colors

For each of your local hours we count how many selected cities are awake (work or free-time in the day template).

• Who’s free / Good (row color + emoji from 🌒 to ☀️): how good the hour is for everyone (hover for the exact count).
• In each city (💤 ⚒️ ☕): sleep / work / awake from the day template for that place’s local hour.

Daylight saving & offsets

Times use the browser’s IANA timezone database via Intl. When you pick a date in March or November, offsets update automatically for zones that observe DST. Melbourne and New York do not switch on the same weekend, for example.

City names come from a GeoNames-based extract (larger cities worldwide plus each country’s main places), each mapped to an IANA zone id. Offsets are never invented by hand.

Sleep / work / awake template

Open Typical day at the bottom of the compare tool. That template is matched to each city’s local hour (not yours). Defaults assume night sleep, daytime work, evening awake, which you edit freely.

• 24-hour clock: midnight at the top, hours clockwise, one slice per hour (15°). Drag the ring to paint.
• AM / PM strips: two rows of twelve hours for precise taps.
• Presets: workday 09–17, all sleep, all awake, or reset.

Share a comparison

Under the schedule, use Copy link (or Share… on supported phones). The link encodes selected cities in the URL. Optionally include the date and your sleep/work/awake day template. Anyone with the link sees that comparison. No account required.

Example: ?z=Europe/London,America/New_York&d=2026-07-15

Tips

• Search by city, country, abbreviation, or IANA id (e.g. Tokyo, UK, USA / America, NYC, Europe/Paris). Type more letters to narrow long result lists.
• Remove a city by tapping its chip.
• Use the 12h / 24h switch next to the date control.
• Many cities scroll sideways in the grid; the first two columns stay put.

More background on why this exists: About.