> For the complete documentation index, see [llms.txt](https://docs.akenza.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.akenza.io/reference/time-range-selector.md).

# Time Range Selector

Absolute, relative, and predefined time ranges, and the DateMath notation behind them.

The **Time Range Selector** appears wherever akenza shows data over a period, from a [dashboard](/dashboard-builder/dashboard-builder.md) to a device's message history. It supports three ways of setting the range:

<table><thead><tr><th width="230">Way</th><th>What it is</th><th>Use it when</th></tr></thead><tbody><tr><td><strong>Date range</strong></td><td>An absolute start and end.</td><td>You are looking at a fixed period, such as a particular week of an incident.</td></tr><tr><td><strong>Relative selection</strong></td><td>An expression in <a href="#datemath-notation">DateMath</a> notation, evaluated whenever the view is opened.</td><td>The range should follow the present, such as "the last 24 hours".</td></tr><tr><td><strong>Quick selection</strong></td><td>A <a href="#predefined-relative-time-ranges">predefined relative range</a> chosen from a list.</td><td>One of the common ranges already fits, which is most of the time.</td></tr></tbody></table>

A relative range matters most on anything left open or shared. A dashboard on a [signage screen](/dashboard-builder/signage-screens.md), or one reached through a [public link](/dashboard-builder/managing-dashboards/public-links.md), keeps showing the right window because the expression is evaluated each time rather than baked in.

{% hint style="info" %}
Rounding happens in the **workspace time zone**, not the viewer's, so `now/d` is the start of the day as the workspace defines it. See [General Settings](/device-management/managing-a-workspace/general-settings.md) for where that is set.
{% endhint %}

## DateMath notation

An expression is formed from three parts:

1. An **anchor date**, either `now` or a date string ending with `||`.
2. An **operator**: `+` to add to the anchor, `-` to subtract from it, or `/` to round it.
3. A **time unit**.

<table><thead><tr><th width="120">Unit</th><th>Meaning</th></tr></thead><tbody><tr><td><code>y</code></td><td>Year</td></tr><tr><td><code>Q</code></td><td>Quarter</td></tr><tr><td><code>M</code></td><td>Month</td></tr><tr><td><code>w</code></td><td>Week</td></tr><tr><td><code>d</code></td><td>Day</td></tr><tr><td><code>h</code></td><td>Hour</td></tr><tr><td><code>m</code></td><td>Minute</td></tr><tr><td><code>s</code></td><td>Second</td></tr><tr><td><code>ms</code></td><td>Millisecond</td></tr></tbody></table>

{% hint style="warning" %}
`M` is month and `m` is minute. The notation is case sensitive, so `now-1M` is a month ago and `now-1m` is a minute ago.
{% endhint %}

### Rounding

`/` rounds the date to the boundary of the given unit. At the **start** of a range it rounds down, to the beginning of that unit; at the **end** of a range it rounds up, to the end of it.

That is what distinguishes a whole period from a period in progress:

* `now/d - now/d` covers the whole of today, midnight to midnight.
* `now/d - now` covers today so far, midnight until this moment.

### Examples

Taking `now` as `2025-01-01 12:00:00`:

<table><thead><tr><th width="210">Expression</th><th width="230">Reads as</th><th>Result</th></tr></thead><tbody><tr><td><code>now+1d</code></td><td><code>now</code> plus one day</td><td><code>2025-01-02 12:00:00</code></td></tr><tr><td><code>now-1m</code></td><td><code>now</code> minus one minute</td><td><code>2025-01-01 11:59:00</code></td></tr><tr><td><code>now-1s/h</code></td><td><code>now</code> minus one second, rounded to hours</td><td><code>2025-01-01 11:00:00</code></td></tr><tr><td><code>2025.01.01||+1M/d</code></td><td><code>2025.01.01</code> plus one month, rounded to days</td><td><code>2025-02-01 00:00:00</code></td></tr></tbody></table>

The third example is worth reading twice: subtracting one second crosses back into the previous hour, and the rounding then takes it to the start of that hour rather than the one `now` is in.

## Predefined relative time ranges

The quick selection offers these ranges. The expressions are shown so that you can start from one and adapt it in a relative selection.

### Hour

| Range            | Expression            |
| ---------------- | --------------------- |
| This hour        | `now/h - now/h`       |
| This hour so far | `now/h - now`         |
| Last hour        | `now-1h/h - now-1h/h` |
| Last 1h          | `now-1h - now`        |
| Last 12h         | `now-12h - now`       |
| Last 24h         | `now-24h - now`       |
| Last 48h         | `now-48h - now`       |

### Day

| Range              | Expression            |
| ------------------ | --------------------- |
| Today              | `now/d - now/d`       |
| Today so far       | `now/d - now`         |
| Yesterday          | `now-1d/d - now-1d/d` |
| This day last week | `now-7d/d - now-7d/d` |
| Last 7 days        | `now-7d - now`        |
| Last 30 days       | `now-30d - now`       |
| Last 90 days       | `now-90d - now`       |

### Week

| Range            | Expression            |
| ---------------- | --------------------- |
| This week        | `now/w - now/w`       |
| This week so far | `now/w - now`         |
| Previous week    | `now-1w/w - now-1w/w` |

### Month

| Range             | Expression            |
| ----------------- | --------------------- |
| This month        | `now/M - now/M`       |
| This month so far | `now/M - now`         |
| Previous month    | `now-1M/M - now-1M/M` |
| Last 6 months     | `now-6M - now`        |

### Quarter

| Range               | Expression            |
| ------------------- | --------------------- |
| This quarter        | `now/Q - now/Q`       |
| This quarter so far | `now/Q - now`         |
| Previous quarter    | `now-1Q/Q - now-1Q/Q` |

### Year

| Range            | Expression            |
| ---------------- | --------------------- |
| This year        | `now/y - now/y`       |
| This year so far | `now/y - now`         |
| Previous year    | `now-1y/y - now-1y/y` |
| Last 1 year      | `now-1y - now`        |

{% hint style="info" %}
Note the difference between the two families. `Last 24h` is a rolling window ending now, while `Yesterday` is a fixed calendar day. Comparing one period against another is only meaningful with the rounded forms, since a rolling window starts at a different point every time it is evaluated.
{% endhint %}


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