> ## Documentation Index
> Fetch the complete documentation index at: https://cubed3-igor-cub-2940-docs-small-multiples.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Axes

> Configure axis titles, grid lines, label formatting, dual Y-axis, and reference lines.

The **Axes** section in the Style tab controls the appearance and behavior of the X axis and Y axis (or left and right Y axes in dual-axis charts). Most axis settings are available for all Vega-based chart types (bar, line, area, scatter, heatmap).

## X axis

| Setting          | Description                                            |
| ---------------- | ------------------------------------------------------ |
| **Show axis**    | Toggle the X axis on or off                            |
| **Title**        | Custom axis label — leave blank to hide the axis title |
| **Grid lines**   | Toggle grid lines perpendicular to the X axis          |
| **Labels**       | Toggle axis tick labels                                |
| **Label angle**  | Rotate axis labels (useful for long category names)    |
| **Label format** | Number or date format applied to axis labels           |

## Y axis (left)

| Setting          | Description                                                      |
| ---------------- | ---------------------------------------------------------------- |
| **Show axis**    | Toggle the Y axis on or off                                      |
| **Title**        | Custom axis label                                                |
| **Grid lines**   | Toggle horizontal grid lines                                     |
| **Labels**       | Toggle axis tick labels                                          |
| **Label format** | Number format applied to axis labels (e.g. `$,.0f` for currency) |
| **Min / Max**    | Override the axis scale minimum and maximum values               |

## Dual Y axis (right axis)

Add a second Y axis on the right side of the chart to plot a series on a different scale. This is useful for combining measures with different units or magnitudes — for example, showing order count on the left axis and average order value on the right.

To use the right axis:

1. In the **Series configuration** for a specific series, change the **Y axis** assignment from **Left** to **Right**.
2. The right axis settings appear in the Style tab — configure its title, labels, and scale independently from the left axis.

## Reference lines

Add horizontal reference lines to mark a target, threshold, or benchmark value. Reference lines appear at a fixed Y value across the full width of the chart.

To add a reference line:

1. In the **Y axis** section of the Style tab, click **Add reference line**.
2. Set the **Value** — the Y position of the line.
3. Optionally set a **Label** that appears next to the line.
4. Configure **Color** and **Style** (solid, dashed, or dotted).

You can add multiple reference lines to the same axis. Each is configured independently.

### Reference line labels

A reference line with no label renders as a bare rule — the reader has to already know what it
means. Type text into **Label** to name it, for example `Target 18k`.

Once a label is set, two alignment controls appear next to it:

| Control        | Options              | Description                             |
| -------------- | -------------------- | --------------------------------------- |
| **Horizontal** | Start / Middle / End | Where along the line the text sits      |
| **Vertical**   | Above / Below        | Which side of the line the text sits on |

New labels start at **End** and **Above** — the right end of the line, clear of the bars. The label
takes the line's color, so it always reads as part of that line. Clearing the label removes the text
and leaves the line itself untouched.

<Tip>
  A label on a line near the top or bottom edge of the plot flips to the other side of the line
  automatically, so the text stays inside the chart area.
</Tip>

<Note>
  Reference lines are only available on the left Y axis. For right-axis reference lines, use a [custom Vega-Lite spec](/docs/explore-analyze/charts/custom).
</Note>