The fastest way to change canvas size in Photoshop

Open the Image menu at the top, select Canvas Size, and a dialog box will appear. Enter your new width and height in pixels (or another unit if you prefer). Click the anchor point diagram to position your existing image where you want it on the new canvas, then click OK. The canvas expands or shrinks around your image based on where you anchored it.

If you want the canvas to expand equally on all sides, click the center square in the anchor diagram before you confirm. If you want the new space only on one side — say, to the right or below — click the anchor point on the opposite side of where you want the space to appear.

The canvas size change happens when ready. Your image layers stay exactly as they are; only the visible workspace around them changes. If you make the canvas smaller than your image, Photoshop will warn you that some content will be clipped, but you can still proceed — the layers themselves are not deleted, just hidden outside the canvas boundary.

Key Takeaways

  • Canvas Size is found under the Image menu and lets you change the visible workspace without resizing your actual image or layers.
  • The anchor point diagram controls where your existing image sits on the new canvas — click the center to expand equally, or click an edge to add space on one side only.
  • You can measure in pixels, inches, centimeters, or other units by typing the unit abbreviation after your number.
  • Making the canvas smaller hides content outside the boundary but does not delete it; you can undo or change the canvas size again to reveal it.

Understanding the difference between canvas size and image size

Canvas size and image size are not the same thing. Canvas size changes only the visible workspace — the rectangular boundary you see around your work. Image size (under Image > Image Size) resizes the actual pixels in your layers, which changes the quality and dimensions of what you have drawn or placed.

Use Canvas Size when you want to add space around your work for a border, frame, or composition change. Use Image Size when you need to make your entire image smaller or larger for printing or web use. If you change canvas size, your layers stay their original size; if you change image size, your layers scale with it.

How to add space on specific sides of your canvas

The anchor point diagram in the Canvas Size dialog is the control. It shows nine squares arranged in a grid. The center square means your image will stay centered as the canvas grows. The corner and edge squares let you push your image to one side, leaving new space on the opposite side.

For example, if you click the top-left square, your image will stay in the top-left corner of the new canvas, and all new space will appear on the right and bottom. If you click the right-center square, your image will stick to the right edge, and new space will appear only on the left. This is useful when you are composing a design and need room for text or another element on a specific side.

Setting canvas size by percentage or specific measurements

The Canvas Size dialog accepts numbers in multiple units. Type the number followed by the unit: px for pixels, in for inches, cm for centimeters, mm for millimeters, or pt for points. Photoshop will convert it automatically.

You can also click the chain link icon between width and height to lock them together. When locked, changing one dimension will scale the other proportionally. Unlock it if you want to change width and height independently — for example, to add height without changing width.

If you want to add a specific amount rather than set a total size, use the relative option. Some versions of Photoshop show a small icon next to the width and height fields; click it to switch between absolute size (the final canvas size) and relative size (how much to add or subtract from the current size).

What happens to layers when you change canvas size

Your layers do not move or resize when you change canvas size. They stay exactly where they are on the canvas. If you shrink the canvas and part of a layer extends beyond the new boundary, that part becomes invisible but is not deleted. You can change the canvas size again later to reveal it, or you can flatten the image to permanently crop the hidden content.

If you have a background layer (a locked layer with no transparency), it will resize to match the new canvas size automatically and fill the new space with the background color. All other layers will remain their original size and position. This is why it is useful to convert a background layer to a regular layer first if you want to preserve its original boundaries.

Centering your image on a larger canvas

To center your image on a new, larger canvas, enter your desired canvas width and height, then click the center square in the anchor diagram. Photoshop will calculate the space needed on all sides and distribute it equally.

If you want to verify the centering before you confirm, look at the offset numbers shown in the dialog. The offset tells you how many pixels your image will move from its current position. Zero offset on both axes means your image will not move; equal positive and negative offsets mean it is centered.

Undoing and adjusting canvas size

If you change the canvas size and do not like the result, press Ctrl+Z (Windows) or Command+Z (Mac) to undo. You can then open Canvas Size again and adjust. There is no limit to how many times you can undo and redo canvas size changes.

If you have already made other edits after changing canvas size, undo will step back through all of them. Use the History panel (Window > History) to jump directly back to the canvas size step without losing later work.

Frequently Asked Questions

Can I change canvas size without losing any part of my image?

Yes. Click the center anchor point so your image stays centered, then increase both width and height. The new space will appear equally on all sides, and nothing will be hidden. If you make the canvas smaller, parts of your image will be hidden unless you position the anchor point to keep the important area visible.

What is the difference between canvas size and crop?

Canvas Size adds or removes space around your image without changing the image itself. Crop permanently removes pixels from the edges. Use Canvas Size if you might want to undo or adjust later; use Crop if you are certain you want to remove that content permanently.

Why does my background layer resize when I change canvas size?

Background layers in Photoshop are locked and do not support transparency. When you change canvas size, Photoshop automatically expands or shrinks the background layer to match the new canvas and fills new space with your background color. Convert it to a regular layer first if you want it to behave like other layers.

Can I change canvas size to a specific aspect ratio?

Yes, but you have to calculate it yourself. Photoshop does not have a built-in aspect ratio tool in Canvas Size. If you need a 16:9 ratio and want a 1920-pixel width, calculate the height (1920 ÷ 16 × 9 = 1080) and enter both numbers. Some users create a custom preset by entering the dimensions once, then saving them for reuse.

What happens to transparent areas if I make the canvas smaller?

Transparent areas outside the new canvas boundary become invisible. If you undo or enlarge the canvas again, they reappear. If you flatten the image or merge layers, the transparent areas are permanently removed and replaced with the background color.