The eraser in Paint sits in the tool box under the name Eraser/Color Eraser. The left mouse button erases, and the right mouse button turns it into a Color Eraser that swaps a single color for another and leaves everything else alone. This guide covers both, along with how to make the eraser bigger or smaller, how to erase to a color other than white, and what changes when the picture is transparent.
Erase part of the picture by dragging the left mouse button
The left button is the plain eraser. The eraser is a square that you drag across the canvas.
- Click Eraser/Color Eraser in the tool box.
- Press and hold the left mouse button over the area you want gone.
- Drag across it. Fast drags still erase a continuous line.
- Let go of the button when the area is clear.
Make the eraser bigger or smaller
The eraser is always a square, and its size is measured in pixels. You can pick a preset or step through sizes from the keyboard.
- With the tool selected, the options area directly under the tool box on the left shows four preset sizes to click: 4, 6, 8 and 10 pixels, with 8 picked until you choose another.
- For a size the presets don't offer, press Numpad + to grow the square or Numpad - to shrink it. Each press changes the size by 1 pixel, anywhere from 1 up to 500 pixels.
Erase to a color other than white
On a normal, opaque picture the eraser doesn't truly remove pixels. It paints them with the secondary color, also called the background color, which is white until you change it. So if your picture has a blue background and you want erased areas to blend in, set blue as the secondary color before you start: right-click blue in the color box, the strip of colors at the foot of the window, then erase as usual. Anything you erase from then on turns blue instead of white.
Replace one color with the Color Eraser
Holding the right mouse button turns the same tool into the Color Eraser. Under the square, it checks each pixel and swaps a pixel for the secondary color only when it is an exact match for the primary (foreground) color. Pixels of any other color are skipped.
- Left-click the color you want to get rid of in the color box. That sets the primary color.
- Right-click the color you want in its place, so it becomes the secondary color.
- Click Eraser/Color Eraser in the tool box.
- Hold the right mouse button and drag over the area.
- Expect only exact matches to change, transparency included: a shade that looks close to the primary color but differs even slightly is left as it is. The color that goes in is exact too, since the tool uses the secondary color precisely as you chose it, including its transparency.
Erase to transparent instead of a color
In Transparent mode, the plain eraser clears pixels completely and leaves holes in the picture. You can switch between Opaque and Transparent in Image > Attributes..., under Transparency. A file that has any see-through pixel opens in Transparent mode automatically.
Other ways to clear areas and undo mistakes
A few other ways to clear parts of a picture:
- To clear a block, select it with a selection tool and press Delete.
- To wipe the whole canvas, choose Image > Clear Image or press Ctrl+Shift+N.
- To replace one color everywhere in the picture at once, hold Shift while you click with Fill With Color.
- To take back an eraser stroke, press Ctrl+Z. Each stroke counts as a single undo step.