How to Compare Two Screenshots Side by Side

To compare two screenshots side by side on Windows, save both as files, open each one in an image viewer, and snap the windows to the left and right halves of the screen with Windows logo key + Left arrow and Windows logo key + Right arrow. That's enough to spot an obvious change. For small differences, such as a two-pixel shift, use a tool that highlights them: WinMerge's image compare (free) or ImageMagick's magick compare command.

Step 1: Get both screenshots into files

The clipboard holds one image at a time, so copying the second screenshot replaces the first. Save each capture as soon as you take it, with matching names such as login-before.png and login-after.png. How to save a copied image with your own file name covers Snipping Tool, Paint and PowerShell.

If clipboard history is on, Win+V keeps both captures for the session, so you can still paste the first one into Paint and save it after taking the second.

Side by side with Windows alone

1. Open login-before.png in Photos or any image viewer.
2. Press Windows logo key + Left arrow to snap it to the left half of the screen.
3. Open login-after.png in a second viewer window.
4. Press Windows logo key + Right arrow to snap it to the right. Windows logo key + Z opens snap layouts if you prefer to pick a layout.
5. Set both windows to the same zoom level before you compare.

This shows a missing button, a colour change or a moved block. It won't show a hairline that moved by a pixel or two; for that, use one of the tools below.

Flip between the two in Paint

Flipping one image on top of the other makes small shifts easier to see than side by side. Windows 11 Paint supports layers, and each layer can be shown or hidden.

1. Open login-before.png in Paint.
2. Open login-after.png in another Paint window, press Ctrl+A and Ctrl+C.
3. Back in the first window, select the Layers button in the toolbar, add a new layer and select it.
4. Press Ctrl+V and line the pasted image up with the top-left corner of the canvas.
5. Hide and show the top layer repeatedly. Anything that jumps is a difference.

Both screenshots need the same size and crop for this to work. Paint is fine for a quick look; it doesn't mark the changed areas for you.

Highlight the differences with WinMerge

WinMerge is an open-source compare tool for Windows that handles images as well as text.

1. Install WinMerge and open it.
2. Select File > Open and choose the before image as the left file and the after image as the right file.
3. Turn on Highlight to mark the changed areas with blocks. Turn on Blink to make the marks flash.
4. Try an Overlay mode (XOR, Alpha Blend or Alpha Blend Animation) to lay one image over the other.
5. If compression noise or anti-aliasing shows up as changes, raise the Color Distance Threshold slider (labelled CD) so small colour differences are ignored.

Generate a difference image with ImageMagick

ImageMagick is a free command-line image tool. Once it's installed, one command writes a third image that shows where the two differ:

magick compare login-before.png login-after.png login-diff.png

In login-diff.png, changed pixels are highlighted in red and unchanged areas are faded out. The diff file is useful to attach to a bug report next to the two originals, and because it's a command, you can run it on whole folders of screenshots from a script.

Make the two captures comparable

Most false differences come from how the screenshots were taken, not from the app:

• Same crop and size. Capture the same window or region both times, and include or exclude the taskbar in both.
• Same display scaling and monitor. A capture at 125% scaling won't line up with one at 100%.
• Same theme. Dark and light mode differ everywhere.
• Same data. Clocks, unread counts and "3 minutes ago" labels always change.
• PNG, not JPEG. JPEG compression changes pixels across the whole image, so every comparison tool reports noise.
• Same colour handling. An HDR capture next to an SDR one can look washed out; Do HDR screenshots survive the clipboard? explains why.

If you compare the same screens build after build, a visual regression testing tool that checks screenshots against a stored baseline will save you doing it by hand. For text rather than images, see how to diff two copied code snippets.

Keep the pair together for review

A before-and-after pair is only useful with a sentence saying what should have changed. When you file it, attach both originals (and the diff image if you made one), note the expected change, and mention anything that always differs, such as timestamps. How QA testers should stage repro data and screenshots and how to collect client feedback screenshots in one place cover the rest of that workflow.

Check the screenshots for anything private, such as email addresses or tokens, before you attach them; how to annotate a screenshot before you reuse it covers redacting them properly.

FAQ

Can I compare screenshots online?

Online image-diff sites work, but they upload both images to someone else's server. For screenshots of internal tools, customer data or unreleased designs, use WinMerge or ImageMagick, which run locally.

Why does every pixel show as different?

The screenshots probably differ in size, scaling or compression. Recapture both at the same scaling as PNG files, crop them to the same region, and compare again.

Can I compare two images copied to the clipboard without saving them?

Not directly. Comparison tools work on files, so save each image first.

Related reading

• How to Save a Copied Image With Your Own File Name
• QA Bug Reports: Stage Repro Steps, Logs, and Screenshots
• How to Annotate a Screenshot on Windows 11
• How to Keep Your Last Ten Screenshots Handy on Windows

Sources

• Keyboard shortcuts in Windows (Microsoft Support) — Win+Left and Win+Right snap windows; Win+Z opens snap layouts.
• Paint app update adding support for layers and transparency (Windows Insider Blog) — Layers button, adding, showing and hiding layers.
• Compare images (WinMerge manual) — File > Open, Highlight, Blink, overlay modes and Color Distance Threshold.
• WinMerge — open-source compare tool with image compare.
• Compare (ImageMagick) — magick compare usage and red highlighting of changed pixels.

Copy. Stack. Drop.

Transform your clipboard into an interactive edge shelf. Stack, pin, and drag assets into any app with zero friction.

Download for Windows Get from Microsoft Store

How to Install Guide · First 10 Minutes Guide · Drag & Drop Guide · Edge Drop vs Win+V · Support