The fastest way: use the bucket fill tool

Open Microsoft Paint and load the image you want to change. Look at the toolbar on the left side of the screen — you will see a paint bucket icon (it looks like a bucket tipping paint). Click it once to select the bucket fill tool.

Next, click the color square in the toolbar to open the color picker. Choose the color you want as your background. Once you have selected it, click anywhere on the background area of your image. The bucket tool will fill that area with your chosen color, as long as the pixels are connected and similar in shade.

If the fill spreads into areas you did not want to change, undo the action by pressing Ctrl+Z and try again. The bucket tool works best on images with clear, defined edges between the background and the object you want to keep.

Key Takeaways

  • The bucket fill tool is the quickest method — select it from the left toolbar, pick your color, and click the background area.
  • If the bucket fill spreads into unwanted areas, your image edges may be too soft or blended; undo with Ctrl+Z and try a different approach.
  • For images with fuzzy or gradual edges, the selection tools let you isolate the background before filling, giving you more control.
  • You can also create a new layer underneath your image and fill that layer instead, which preserves your original image on top.

When the bucket tool does not work cleanly

The bucket fill tool works by detecting edges — it stops filling when it hits a color that is different enough from the area you clicked. If your image has soft edges, a feathered outline, or a gradient background, the bucket will either leave gaps or spill into areas you want to keep.

In these cases, use a selection tool first. Click the "Select" menu at the top, then choose "Select by Color" or "Free-form Select" depending on your image. Trace around the object you want to keep, leaving the background unselected. Then go to the Edit menu, choose "Fill with Color", and pick your new background color. This method gives you precise control over what gets filled.

Using layers to protect your original image

If you want to experiment with background colors without changing your original image, create a new layer underneath it. Go to the Image menu and look for "Canvas Size" or "Layers" (the exact menu name varies by Paint version). Create a new layer, move it below your current image layer, and fill that new layer with your chosen color.

This approach is useful if you think you might want to change the background color again later or try multiple options. You can always delete the colored layer and start over without affecting the image on top.

Removing a background before adding a new color

If your image has a background you want to remove entirely before adding a new color, use the eraser tool or a selection method. Select the background using "Select by Color" from the Select menu, then press Delete to remove it. This leaves a transparent background (shown as a checkerboard pattern in Paint). You can then add a solid color layer underneath, or fill the transparent area with a new color using the bucket tool.

Be aware that Paint's transparency support is limited compared to other image editors. If you plan to use transparency, save your file as a PNG rather than a JPG, since JPG does not support transparent areas.

Choosing the right color format

When you click the color square to pick a color, Paint shows you several ways to choose. You can click a preset color from the palette, use the color picker to sample a color from your image, or enter specific values if you know the exact shade you want. The RGB (red, green, blue) system is the most common — each color is made from a mix of red, green, and blue light, with values from 0 to 255.

If you are matching a color from somewhere else — a logo, a brand guideline, or another image — the eyedropper tool (usually near the color square) lets you click any color on your screen and use it. This is faster and more accurate than trying to guess or manually enter numbers.

Saving your work in the right format

Paint saves files in several formats. JPG works well for photographs and images with many colors, but it does not support transparency. PNG preserves transparency and is better for images with solid colors or if you might edit the background again later. BMP is Paint's native format but creates larger files. For most background color work, PNG or JPG are your best choices depending on whether you need transparency.

Go to File, then "Save As", and choose your format from the dropdown menu. If you are not sure, PNG is the safer choice — it handles both solid colors and transparency without quality loss.

Frequently Asked Questions

Why does the bucket tool fill my entire image instead of just the background?

This usually means the background and your main object are not separated by a clear color boundary. The bucket tool sees them as connected. Use a selection tool instead: go to Select menu, choose "Select by Color", click the background, then use Edit > Fill with Color to change only the selected area.

Can I undo a bucket fill if I made a mistake?

Yes. Press Ctrl+Z when ready after the fill, and Paint will undo the last action. You can undo multiple steps by pressing Ctrl+Z repeatedly. If you have already saved the file, undo will not work — you will need to reopen the original version.

What is the difference between filling on a layer versus filling the background directly?

Filling directly changes your image permanently. Filling a separate layer underneath keeps your original image intact on top and lets you change or remove the background color later without affecting the main object. Layers give you more flexibility if you think you might want to adjust your choice.

How do I match a specific color I see in another program?

Use the eyedropper tool in Paint's color picker. Click the eyedropper icon, then click anywhere on your screen — even in another window — to sample that exact color. Paint will load it as your current color, and you can then use it to fill your background.

Does Paint work with images that have transparent backgrounds?

Paint can open PNG files with transparency, but its transparency support is basic. You can see transparent areas as a checkerboard pattern, but Paint is not designed for detailed transparency work. If you need to add a background to a transparent image, fill a new layer underneath it or use the bucket tool to fill the transparent area directly.