What Happens When You Merge Down in Paint.NET

Merging a layer down in Paint.NET combines the currently selected layer with the layer directly beneath it into a single, unified layer. This process permanently blends the visual elements, opacity levels, and blend modes of the upper layer into the lower layer, simplifying your project structure and reducing the overall layer count by one.

Pixel Integration

When you trigger the "Merge Layer Down" command, Paint.NET renders the upper layer's pixels directly onto the canvas of the layer below it. Any transparent areas in the upper layer allow the lower layer's content to remain visible, while opaque pixels overwrite or combine with the content underneath. Once merged, the elements from both layers occupy the same pixel space and can no longer be moved, transformed, or selected independently without manually cutting them out.

Blending Modes and Opacity

Any layer properties applied to the upper layer—such as reduced opacity or blend modes like Multiply, Screen, or Overlay—are permanently baked into the resulting layer. During the merge, Paint.NET calculates how the upper pixels interact with the lower pixels based on those settings and produces a flat, standard pixel result. The merged layer retains the layer properties (name, visibility, and blend mode) of the original lower layer.

Layer Stack Changes

The upper layer is removed from the Layers window entirely. The resulting combined layer sits at the exact position in the stack previously occupied by the lower layer. This helps declutter complex projects, minimizes system memory usage, and organizes complex compositions into manageable components.

Permanence and Reversibility

Merging down is a destructive editing action. While you can immediately undo the operation using the History window or by pressing Ctrl + Z, you cannot unmerge the layers once the project is closed or the history states are cleared. If you save the file in Paint.NET's native .pdn format after merging, the layers remain fused the next time you open the document.

To merge a layer down in Paint.NET, select the upper layer in the Layers window and either click the Merge Layer Down icon (two overlapping sheets with a down arrow) at the bottom of the window or press the keyboard shortcut Ctrl + M.