How to Add Rounded Corners in Paint.NET

Adding rounded corners to a rectangular image or button in Paint.NET creates a modern, polished look for web design and digital graphics. This guide walks you through the fastest native method to round any image or button corners using the Shapes tool and layer masking, ensuring transparent outer edges without requiring third-party plugins.

Method: The Shape Masking Technique

This native technique uses a temporary layer to define the rounded boundary and cut away the excess sharp edges.

  1. Open Your Project
    • Launch Paint.NET and open the image or button you want to edit.
    • If working with a standard background layer, double-click the layer in the Layers window and rename it, or simply leave it unlocked.
  2. Create a Mask Layer
    • Go to the Layers menu at the top and select Add New Layer (or press Ctrl + Shift + N).
    • Ensure this new layer is situated directly above your image layer and selected.
  3. Draw the Rounded Rectangle
    • Select the Shapes tool from the toolbar (keyboard shortcut: O).
    • In the top options bar, change the shape type dropdown from "Rectangle" to "Rounded Rectangle".
    • Set the fill style to "Draw Filled Shape".
    • Adjust the Corner size metric in the top toolbar to determine how round your corners will be (higher values create rounder edges).
    • Click and drag the shape over your button or the portion of the image you want to keep, aligning it with the edges.
  4. Select the Rounded Area
    • Choose the Magic Wand tool from the toolbar (shortcut: S until the wand is selected).
    • Click anywhere inside the solid rounded rectangle you just drew to highlight it with a selection outline.
  5. Invert and Delete the Corners
    • Go to the Edit menu and click Invert Selection (shortcut: Ctrl + I). The selection will now encompass only the four sharp corner areas outside the rounded shape.
    • In the Layers window, click on your original image or button layer to make it active.
    • Press the Delete key on your keyboard. The square corners will disappear, revealing the checkerboard transparency pattern.
  6. Clean Up and Save
    • In the Layers window, select the temporary shape mask layer and click the red Delete Layer icon (or press Ctrl + Shift + Delete).
    • Press Ctrl + D to clear your selection.
    • Save your file by going to File > Save As... and selecting **PNG (*.png)** to preserve corner transparency.