Formatting insight axes

PostHog renders insights with a built-in axis formatter. Use it instead of contorting the query or a literal prefix/postfix to fake units.

The two insight kinds configure it in different places:

TrendsQuery —
```
trendsFilter.aggregationAxisFormat
```
(this page, below)
SQL insights (
```
DataVisualizationNode
```
) — per-column
```
settings.formatting
```
(see SQL insights)

The anti-pattern

If you are reaching for any of these, stop and pick a format below first:

formula: "A / 60"

with

aggregationAxisPostfix: " mins"

— manual seconds -> minutes

formula: "A / 1000"

with

aggregationAxisPostfix: " s"

— manual ms -> seconds

formula: "A * 100"

with

aggregationAxisPostfix: "%"

— manual ratio -> percent

aggregationAxisPostfix: "ms"

"s"

"min"

"hr"

on raw values

These freeze the unit at one scale. The built-in formatter picks a friendly unit per value (1.5s, 2m 12s, 1h 4m) and keeps the underlying series numerically correct for further math, breakdowns, and alerts.

Available formats

Set

trendsFilter.aggregationAxisFormat

on the TrendsQuery:

Value	Use when the series is...	Renders as
`numeric` (default)	a plain count	`1,234`
`duration`	seconds (any scale)	`45s` , `2m 12s` , `1h 4m`
`duration_ms`	milliseconds	`850ms` , `1.5s` , `1m 4s`
`percentage`	already 0-100	`47.3%`
`percentage_scaled`	a ratio 0-1	`47.3%`
`currency`	money in the project's base currency	`$1,234.56` (or local code)
`short`	large counts you want compacted	`1.2K` , `3.4M`

Companion fields on

trendsFilter

```
aggregationAxisPrefix
```
— literal prefix (e.g.
```
"$"
```
) when you need a symbol pinned to a specific currency or unit, regardless of project settings
```
aggregationAxisPostfix
```
— literal suffix; reserve for genuine units the format can't express (e.g.
```
" req"
```
,
```
" events"
```
), never for
```
"mins"
```
/
```
"s"
```
/
```
"%"
```
— the percentage formats already append the
```
%
```
sign, so a
```
"%"
```
postfix renders
```
50%%
```
```
decimalPlaces
```
— cap decimals (1 or 2 is usually right for currency / ratios)

Currency — pick

format

prefix

carefully

aggregationAxisFormat: "currency"

renders with the project's base currency (set in project settings, defaults to USD). Use it when the underlying values are in that same currency — e.g. revenue events that PostHog auto-converts to the project's base currency.

If the values are pinned to a specific currency regardless of project (e.g.

$ai_total_cost_usd

is always USD, even on a EUR-base project), use

aggregationAxisPrefix: "$"

decimalPlaces: 2

so the symbol matches the data. Using

format: "currency"

here would render USD values with

€

on a EUR project.

When the series is in seconds

If the series is in seconds (latency, session length, time-to-first-event, processing time, page load, etc.), silently default to

aggregationAxisFormat: "duration"

. Do not stop to ask — the formatter is non-destructive (the underlying values stay in seconds either way, only the labels change), so picking it is always at least as good as raw seconds.

Only confirm with the user when they have explicitly named a fixed unit they want pinned ("show this in minutes", "graph the average in hours"):

"I can pin the y-axis to minutes by dividing the series by 60, or use PostHog's
duration
formatter which auto-picks seconds / minutes / hours per value —
90s
renders as
1m 30s
and
5400s
as
1h 30m
. Which would you prefer?"

In one-shot MCP contexts where no user is in the loop, just pick

duration

and move on.

Examples

Latency — duration in milliseconds

json

{
  "kind": "TrendsQuery",
  "series": [
    {
      "kind": "EventsNode",
      "event": "$pageview",
      "math": "p95",
      "math_property": "$performance_page_loaded"
    }
  ],
  "trendsFilter": {
    "aggregationAxisFormat": "duration_ms"
  }
}

Average session length — duration in seconds

json

{
  "kind": "TrendsQuery",
  "series": [
    {
      "kind": "EventsNode",
      "event": "$pageleave",
      "math": "avg",
      "math_property": "$session_duration"
    }
  ],
  "trendsFilter": {
    "aggregationAxisFormat": "duration"
  }
}

Revenue — currency in the project's base currency

json

{
  "trendsFilter": {
    "aggregationAxisFormat": "currency",
    "decimalPlaces": 2
  }
}

Fixed-currency value (e.g. LLM cost in USD) — pin the symbol

json

{
  "trendsFilter": {
    "aggregationAxisPrefix": "$",
    "decimalPlaces": 2
  }
}

Conversion rate — percentage from a 0-1 formula

json

{
  "kind": "TrendsQuery",
  "series": [
    {
      "kind": "EventsNode",
      "event": "checkout_completed",
      "math": "dau"
    },
    {
      "kind": "EventsNode",
      "event": "checkout_started",
      "math": "dau"
    }
  ],
  "trendsFilter": {
    "formula": "A / B",
    "aggregationAxisFormat": "percentage_scaled",
    "decimalPlaces": 1
  }
}

SQL insights (DataVisualizationNode)

SQL insights have no

trendsFilter

. Formatting is per column, on

chartSettings.yAxis[].settings.formatting

for a chart and top-level

tableSettings.columns[].settings.formatting

for a table.

json

{
  "kind": "DataVisualizationNode",
  "source": { "kind": "HogQLQuery", "query": "SELECT week, conversion_rate FROM ..." },
  "display": "ActionsLineGraph",
  "chartSettings": {
    "xAxis": { "column": "week" },
    "yAxis": [
      {
        "column": "conversion_rate",
        "settings": { "formatting": { "style": "percent", "decimalPlaces": 1 } }
      }
    ]
  }
}

style

none

number

short

, or

percent

— no

duration

currency

. Express those with

prefix

suffix

, or in the SQL itself.

percent

both appends the

sign and multiplies the value by 100 (like the trends

percentage_scaled

format; there is no unscaled variant). So feed it a 0-1 ratio and leave

suffix

unset — pick one shape, never a mix:

SQL returns	`formatting`	Renders
a 0-1 ratio ( `a / b` )	`{"style": "percent", "decimalPlaces": 1}`	`47.3%`
0-100 ( `round(100.0 * a / b, 1)` )	`{"style": "number", "suffix": "%", "decimalPlaces": 1}`	`47.3%`

A mix renders broken:

style: "percent"

plus a

"%"

suffix gives

47.3%%

, and

percent

on an already-scaled 0-100 column gives

4730%

. Prefer the ratio form — it keeps the

100.0 *

out of the query, so the stored column stays a plain ratio for anything else that reads it.

Updating an existing insight

If an insight you are already editing uses one of these anti-patterns — a trends

formula

postfix

pair, or a SQL column with both

style: "percent"

and a

"%"

suffix — fix it in the same

posthog:insight-update

call: drop the divide-by-N or

100.0 *

and the literal

, and let the format own the unit. Values stay the same, only labels change. Do not scan unrelated insights — fix only the ones you are already touching.

formatting-insight-axes

NPX Install

Tags

SKILL.md Content

Formatting insight axes

The anti-pattern

Available formats

Currency — pick
`format`
or
`prefix`
carefully

When the series is in seconds

Examples

Latency — duration in milliseconds

Average session length — duration in seconds

Revenue — currency in the project's base currency

Fixed-currency value (e.g. LLM cost in USD) — pin the symbol

Conversion rate — percentage from a 0-1 formula

SQL insights (DataVisualizationNode)

Updating an existing insight

formatting-insight-axes

NPX Install

Tags

SKILL.md Content

Formatting insight axes

The anti-pattern

Available formats

Currency — pick format or prefix carefully

When the series is in seconds

Examples

Latency — duration in milliseconds

Average session length — duration in seconds

Revenue — currency in the project's base currency

Fixed-currency value (e.g. LLM cost in USD) — pin the symbol

Conversion rate — percentage from a 0-1 formula

SQL insights (DataVisualizationNode)

Updating an existing insight

Currency — pick
`format`
or
`prefix`
carefully