---
title: "Boss’nX schema: set the canvas size, format and grid"
description: "Set the size of a Boss’nX schema: 16:9, 4:3, 1:1 or 21:9 formats, custom width and height from 100 to 4000, snapping grid and grid step from 2 to 200 px."
canonical: https://wiki.can-nx.com/en/guides/boss-schema-canvas/
language: en
product: Boss’nX
audience:
  - administrateur
  - installateur
context: "Boss’nX schema editor on a computer: dimensions and grid in the bottom bar"
---

# Boss’nX schema: set the canvas size, format and grid

Context: Boss’nX schema editor on a computer: dimensions and grid in the bottom bar

In the schema editor of a Boss’nX supervision, the bottom bar sets the size of the drawing, with a preset format (16:9, 4:3, 1:1, 21:9) or a custom width and height, as well as the placement grid and its snapping. These settings change the drawing surface; to simply enlarge the view or find the drawing on screen, use [zoom and framing](https://wiki.can-nx.com/en/guides/boss-schema-canvas-navigation/).

Intended for administrators and installers who edit schemas, on a computer.

## Before you start

- Your role has **View schemas** and **Edit schemas**. If the edit entry is missing, see [the role capabilities](https://wiki.can-nx.com/en/guides/boss-role-capabilities/).
- A sufficiently wide screen makes the bottom bar easier to reach.

## Open the schema on the right layer

1. From the supervision Dashboard, open **Schemas** in the header bar, or **Menu → Schemas**.
2. Hover over the schema you want in the left panel, then open **Actions → Edit schema**. Wait for its name and content to load.
3. Check the active layer at the bottom right. To change it, open **Layers**, stacked-sheets icon, then click its name. [Layer management](https://wiki.can-nx.com/en/guides/boss-schema-layers/) details these operations.
4. In the bottom bar, find the dimensions shown as **width × height**, then the list of formats.

## Choose a format

Select the format you want in the list of the bottom bar:

| Format shown | Dimensions |
| --- | --- |
| 16:9 (Full HD) | 1920 × 1080 |
| 4:3 (Standard) | 1600 × 1200 |
| 1:1 (Square) | 1200 × 1200 |
| 21:9 (Ultra-wide) | 2560 × 1080 |
| Custom | W and H fields |

The choice applies to the drawing being edited. **Custom** takes the dimensions of the background image when they are available, otherwise it starts from **1920 × 1080**; check the values displayed, then adjust them. The effects of an image import on the size are described in the [canvas background](https://wiki.can-nx.com/en/guides/boss-schema-background/) guide.

## Enter a width and a height

1. Choose **Custom** to display **W**, the width, and **H**, the height.
2. Between the two fields, find the padlock. Its tooltip shows **Ratio locked** or **Ratio unlocked**; a click changes this state.
3. To set two independent values, switch to **Ratio unlocked**, click in W, enter the width and confirm with **Enter**. Do the same in H for the height. Fictitious example: W **1000**, H **600**.
4. To keep a proportion, switch to **Ratio locked** and change only one dimension: the other one adapts. Always check both values, especially after an import or a layer change.
5. Check the width × height shown in the bar and the position of the elements. If needed, use **Fit to screen** to see the whole drawing after the size change.

The custom fields accept dimensions from **100 to 4000**. An entry outside this range is brought back to the corresponding limit; after Enter or leaving the field, read the value retained. You can also drag the W and H labels horizontally to adjust their value.

Resizing can move the elements to keep their relative position on the surface. Check their layout and the other layers before saving. Zoom corrects neither a position nor a dimension of the drawing.

## Turn on the grid and set its step

1. In the bottom bar, click the grid icon, tooltip **Grid & snap — Alt to place freely**. This button turns grid display and snapping on or off together.
2. With the grid on, open the neighboring button showing a number and **px**, tooltip **Grid step**.
3. Choose **Fine** 8 px, **Medium** 16 px, **Standard** 24 px, **Large** 32 px or **Extra large** 48 px, or enter a whole number from **2 to 200** in **Custom…**.
4. A valid custom value applies as you type. Read the number shown on the Grid step button to check the value retained. **Esc** or a click outside closes the list.

With the grid on, hold the Alt key while moving an element to place it freely, without snapping. When the grid is off, the Grid step button is grayed out. The grid and its step concern the **schema**: changing layers does not create an independent grid setting. The **Grid** pattern of the background picker is a different setting: it decorates the layer and does not replace this snapping button.

## Save the settings

1. Check the layer, the dimensions and the layout of the elements.
2. Click **Save** in the left panel, then review and confirm **Save schema?**. Handle any warnings or [conflicts between layers](https://wiki.can-nx.com/en/guides/boss-schema-conflicts/) before continuing.
3. Wait for **Configuration saved successfully.** and check the layer summary.

## Check the result

To confirm the save, reopen the schema:

1. Return to **Schemas**, from the header bar or the **Menu**, explicitly choose the right schema, then open **Actions → Edit schema**. Wait for it to load and find the layer you want in Layers.
2. Check the dimensions, the grid step and the elements after reopening.

## Troubleshooting

- The **Unsaved changes** box appears when you thought you were done: choose **Stay** and review the save result. To keep a change that is still pending, avoid **Leave without saving**.
- A resize needs to be undone while you are still in the editor: use [Undo and Redo](https://wiki.can-nx.com/en/guides/boss-schema-canvas-navigation/).
- A setting is missing or the result is unexpected: see [the canvas questions and checks](https://wiki.can-nx.com/en/guides/boss-schema-canvas-help/).

If the Unsaved changes box appears again after checking and saving, contact support@can-nx.com with the schema, the layer, the desired values, the message and the steps already tried.

French labels: **Menu → Schémas**, **Actions → Modifier le schéma**, **Calques**, **Personnalisé**, **W**, **H**, **Ratio verrouillé**, **Ratio déverrouillé**, **1:1 (Carré)**, **21:9 (Ultra-large)**, **Ajuster l'écran**, **Grille et magnétisme — Alt pour placer librement**, **Pas de grille**, **Fin**, **Moyen**, **Standard**, **Large**, **Très large**, **Personnalisé…**, **Sauvegarder**, **Sauvegarder le schéma ?**.