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Audience Time Zone Post Planner

Social Media
Audience coverage, not advice about timing

Audience coverage is the share of your audience whose local time at this slot falls inside the active-hours window you set for them. It is arithmetic over your inputs, not a forecast of how a post will do.

This tool never ranks a slot or suggests when to publish. It converts one clock time into every segment's local time and reports the share that falls inside a window you set.

Your zone and the week you are evaluating

The zone you think and schedule in. Every grid column is labelled in it.
Any date inside the week to evaluate. Daylight saving makes the answer week-dependent.
Sets the row order and every weekday sequence.
Clock format and grid column width.

Audience segments

3 of 12

Example mixes, not benchmark data - they only save typing while you try the tool.

09:00-22:00 is an assumption you can change, not measured data. Coverage is whatever your own window implies. A window includes both ends, so 22:00 counts as inside a 09:00-22:00 window. Set start and end to the same time to mean all day. Weights are normalised, so follower counts, survey totals and raw percentages all work.

Coverage week grid

Every cell is one candidate slot, labelled in UTC. Fill depth is coverage. Select a cell to break it down below.

0%

50%

100%

The grid appears once at least one segment has a valid zone and a weight above zero.

Because daylight saving rules differ per zone, the same clock time in a different week can produce a different result. This grid shows the week beginning —. Struck-out cells are clock times that do not exist in UTC that day; a dot in the corner marks an hour that happens twice.

Selected slot

Add a usable segment to see the breakdown for a slot.

Everything above runs in your browser with no network calls, and the zone rules come from your own browser's time zone database. Need dated schedules or calendar export? Use the Social Media Content Calendar Generator. Working out how often to publish is the Posting Frequency Planner.

About This Tool

Audience Time Zone Post Planner – One Clock Time, Many Local Times

A creator with a distributed audience faces a small, concrete question that spreadsheets answer badly: if I publish at this wall-clock time in my own zone, what local time and weekday does that become for each slice of my audience? Friday 18:00 in Berlin is Friday 09:00 in Los Angeles and Saturday 02:30 in Mumbai — and that Saturday is the detail that usually gets missed. This audience time zone post planner does that conversion for up to twelve audience segments at once and reports how much of your weighted audience is inside the hours you assumed for them.

It will not tell you when to publish
There is no authoritative source for a universally correct publishing time — the tables circulating online are vendor marketing drawn from one platform, one niche and one year, and they contradict each other. Coverage here is arithmetic over assumptions you typed, not a prediction.

What coverage means

Each segment carries a weight — follower count, survey respondents, an analytics percentage — and the tool normalises them so the units never matter:

share = weight / Σ weights

A slot is then resolved to a single instant in time, and every segment's local clock reading at that instant is compared against its own active window:

coverage = Σ share of segments whose local time is inside their window

The active window defaults to 09:00–22:00 because something has to appear in the box, and it is editable per segment. Both ends count as inside, windows that cross midnight wrap correctly, and setting the start equal to the end means all day. Nothing else feeds the number: no engagement history, no platform statistics, no benchmarks.

Daylight saving is the hard part

Turning a wall clock into an instant is where naive conversions break. Twice a year, in every zone that shifts, one wall-clock hour never happens and another happens twice. Ask for 02:30 in New York on a March transition date and the honest answer is that no such moment exists — so those cells are struck out and, if you select one, a warning names the jump and the substituted time. On the autumn date an hour repeats, so the tool flags it, uses the first occurrence and offers a toggle for the second, listing both UTC instants. Offsets are read at the resolved instant, never stored as a zone's identity, so half-hour and quarter-hour zones such as Asia/Kolkata (+05:30), Asia/Kathmandu (+05:45) and Australia/Lord_Howe — whose clocks move by thirty minutes, not sixty — all render exactly.

Reading the grid and the day strips

The week grid is the fastest way in: rows are the seven days of the week you selected, columns are every slot of the day in your own zone, and fill depth is coverage. Each cell is resolved against its real calendar date, which is why a transition week genuinely contains a 23- or 25-hour day. Below it, one horizontal strip per segment shows that segment's whole day with its active window shaded and a marker where your post lands — the moment where you see the marker sitting well outside the shaded band for a large segment is usually the moment the trade-off becomes obvious. Pin up to three slots to compare them directly.

Everything stays in your browser

No data is sent anywhere. Time zone rules come from your own browser's ICU database, which your browser and operating system keep current as governments change their rules, and your segment mix is saved locally so it survives a reload. If a saved zone identifier is one your browser no longer recognises, the row is dropped and you are told, rather than the page failing quietly.

Frequently Asked Questions

Is the Audience Time Zone Post Planner free?

Yes, Audience Time Zone Post Planner is totally free :)

Can I use the Audience Time Zone Post Planner offline?

Yes, you can install the webapp as PWA.

Is it safe to use Audience Time Zone Post Planner?

Yes, any data related to Audience Time Zone Post Planner only stored in your browser (if storage required). You can simply clear browser cache to clear all the stored data. We do not store any data on server.

What does audience coverage actually measure?

Exactly one thing: the share of your weighted audience whose own local time, at the slot you selected, falls inside the active-hours window you set for them. Nothing else goes into it — no engagement data, no platform statistics, no benchmarks. If you tell the tool your London segment is awake from 09:00 to 22:00 and the slot lands there at 03:00, that segment counts as outside and its share drops out of the total. Coverage is an arithmetic consequence of your own assumptions, not a prediction of how a post will perform.

Will this tell me when to publish?

No, and that is deliberate. No universal best posting time exists: the figures circulating online come from single vendors sampling one platform, one niche and one year, and they contradict each other freely. This tool never ranks a slot as good or bad. It converts one clock time into every segment's local time and reports the share that falls inside a window you defined. Which trade-off is worth taking — a slot that reaches 60% of your audience comfortably, or one that reaches 95% at the cost of your own midnight — is your call, not the calculator's.

What happens on daylight saving change days?

Both awkward cases are handled rather than hidden. When the clocks spring forward, the skipped wall-clock times genuinely do not exist — 02:30 is never a real moment in New York on the March transition date — so those grid cells are struck out, and picking one shows a warning naming the jump and the substituted time actually used. When the clocks fall back, an hour repeats, so the tool flags the slot, defaults to the first occurrence and gives you a toggle for the second, listing both UTC instants.

Why does a segment show a different weekday to mine?

Because a single instant is a different calendar date in different parts of the world. Wednesday 22:00 in New York is already Thursday 03:00 in London and Thursday 07:30 in Kolkata. Any row whose local date differs from yours is badged +1 day or −1 day and shows its own weekday, since a Friday evening post for you can be a Saturday morning post for a large slice of your audience — which usually matters more than the hour itself.

How are the segment weights used?

They are normalised, so the units never matter. Enter raw follower counts, survey respondents, analytics percentages or rough guesses, and each segment's share is simply its weight divided by the total of all weights, shown to one decimal place. A row with a negative or non-numeric weight is flagged and excluded from the total instead of poisoning it, and if every weight is zero the results panel is disabled with an explanation rather than showing meaningless output.

Why does the same clock time give a different answer in another week?

Because daylight saving rules differ by zone and by date. Europe, North America and Australia change clocks on different weekends, and in the weeks between those dates the gap between two zones is temporarily an hour off its usual value — so 15:00 in London can be 10:00 or 11:00 in New York depending on the week. The grid therefore resolves every cell against its real calendar date in the week you selected, and the tool states which week that is. Nothing is sent anywhere to work this out: all the zone rules come from your own browser's time zone database, and the whole tool runs locally with no network calls.