How to Compress a PNG in Photoshop

You open a file in Photoshop, and the first big question is how to compress png in photoshop without wasting time on an export path that changes nothing. The actual file size comes from two sources: the raw pixel data and the metadata wrapped around it. Photoshop gives you three separate tools to attack both, and each one works in a completely different way.

The palette reduction checkbox in Export As is the same lossy process that online compressors like TinyPNG use. It is called "Smaller File (8-bit)" in Photoshop, but underneath it rebuilds the image from an adaptive palette of up to 256 colours. That one checkbox combines two compounding effects: each pixel needs 7 or 8 bits instead of 24 or 32, and thousands of near identical shades collapse into one entry, creating the repetition that PNGs compression algorithm feeds on.

The Three Export Routes Ranked

File > Save As gives you nothing. The dialog offers no compression setting, no colour reduction, no size readout. It saves a perfectly lossless PNG with all metadata intact. Use it only when you need the exact original bytes.

File > Export > Export As is the middle option. It shows a panel with a "Smaller File (8-bit)" checkbox. Tick that checkbox and Photoshop converts the image to an indexed palette of 256 colours. This is palette reduction under a friendlier name. The panel also includes an Image Size section that scales the export without altering the document. The export preserves transparency through a tRNS chunk, one alpha value per palette entry, so semi transparent pixels may lose the soft edge you designed.

File > Export > Save for Web (Legacy) gives the finest control. The dialog offers a PNG-8 mode with a Colors dropdown that goes down to 2 colours. A Dither slider lets you trade smoothness against size. A live file size readout updates as you change any setting. And here is the key advantage: Save for Web is where you can go below 256 colours in Photoshop. Reducing the palette to 128 or 64 colours typically cuts file size by another 20 to 30 per cent, with visible banding only in gradients.

Photoshop Save for Web PNG-8

To use Photoshop Save for Web PNG-8 effectively, open Save for Web (Legacy) from the File menu. In the top right preset dropdown choose PNG-8. The Colors value defaults to 256. Lower it step by step watching the live size readout at the bottom left of the dialog. The readout is your honest guide.

A screenshot or UI element at 128 colours often shows no visible difference and cuts file size by 50 per cent or more. A photograph stored as PNG needs 256 colours and even then may show banding. For a photograph stored as PNG the honest answer, if size matters, is to change format to JPEG. JPEG discards high frequency detail the eye struggles to notice and can shrink a photo by 90 per cent compared to PNG of the same dimensions.

The visible failure mode for palette reduction is banding in smooth gradients. A soft fade needs many closely spaced colours to look continuous. The second failure mode is a stair step fringe on semi transparent edges, worst on curves and diagonals. A gentler dither setting in the Save for Web dialog softens both.

Photoshop Export as Smaller File 8 Bit

Photoshop Export As smaller file 8 bit is the simplest one click reduction in the program. Open File > Export > Export As. Set Format to PNG. Tick the checkbox labelled "Smaller File (8-bit)". That is the entire instruction.

The checkbox forces the export to build an indexed palette of exactly 256 colours. You cannot go lower in Export As. You cannot control dithering or see the resulting file size before you save. The panel does show a pixel dimension preview, and the Image Size section lets you rescale before export, which is a separate saving that multiplies the effect of palette reduction.

A UI screenshot at 8-bit typically shrinks by 70 to 85 per cent. A logo or icon by 60 to 80 per cent. A photograph stored as PNG by 40 to 70 per cent. And an already optimised PNG by zero per cent. Re compressing a palette reduced file a second time gives a worse result than going to the low colour count once, because the second pass chooses from an already impoverished set of colours. Keep the original.

Which Photoshop Export Route Gives the Smallest PNG

The answer is Save for Web (Legacy) with PNG-8 and a reduced colour count. It is the only route that lets you set a palette smaller than 256 colours and the only one with a live size readout. That readout means you can tune the file to hit a target like 100 KB without guessing.

Export As with the 8-bit checkbox is the fastest route if you only need 256 colours and you accept whatever size results. Save As gives no size reduction at all. A chart or diagram at 64 colours in Save for Web can land at 30 KB. The same file saved the naive way through Save As may be 300 KB. The difference is non negotiable back end work the other routes skip.

For a photograph stored as PNG the honest answer is that none of the three routes solves the problem. Palette reduction on a photo at 256 colours typically saves 40 to 70 per cent, but the output is still two to five times larger than the same frame as a JPEG at reasonable quality. JPEG handles photographic noise the way PNG cannot, because PNG promises exact pixels and noise is incompressible. Switch format instead.

How PNG Compression Works in Photoshop

PNG is always compressed and always lossless. There is no uncompressed PNG. The algorithm works in two stages. First filtering: for each row the encoder picks one of five filter types that predicts each pixel from its neighbours and stores the difference. Then DEFLATE, the zlib algorithm, compresses the filtered bytes.

What Makes PNG Small

Flat colour, sharp edges and repeated patterns make the prediction correct. The differences become mostly zero, and zeros compress to almost nothing. A solid colour icon at 100 by 100 pixels can be under 1 KB.

What Makes PNG Huge

Photographic sensor noise makes the prediction wrong nearly every time. The differences are small random numbers that DEFLATE cannot compress. A photograph as PNG is roughly ten times the size of the same photo as JPEG at a quality difference invisible at normal viewing distance.

Lossless Optimisation in Photoshop

Photoshop does not expose a lossless optimisation pass like optipng or zopflipng. Those tools search harder for the best filter per row, re run DEFLATE at maximum effort, and strip metadata chunks. Typical saving from such tools is 5 to 15 per cent, sometimes zero on an already optimised file. If you need that last 10 per cent, run the exported file through a lossless optimiser on the command line or use ImageOptim on macOS.

Practical Steps for Compressing in Photoshop

Open the PNG you need to shrink. Do not use Save As. You are about to learn how to compress png files in photoshop properly, and that starts with the Export menu.

For a first attempt go to File > Export > Save for Web (Legacy). Select PNG-8. Set Colors to 256. Watch the size readout. If the file is still too large, reduce the color count to 128, then 64. Each step costs you some gradation smoothness and gains you kilobyte. The readout shows the result instantly.

If the image has soft transparency like a drop shadow or a rounded logo, use a dither setting of 80 to 100 per cent in the Save for Web dialog. That softens the stair step fringe at a tiny cost in file size.

Resize the image in the Image Size panel before you apply colour reduction. File size scales with pixel count, so doubling the width quadruples the data. For a blog image aim at roughly 1600 pixels on the long edge. For high density screens about 2560 pixels covers full screen use. Resizing before compressing is doubly effective because the compressor performs better on the smaller image.

To know how to compress png image in photoshop thoroughly, keep the original file. Palette reduction cannot be undone. Compress a copy and keep the print ready original aside. Print resolution is far higher than screen and exposes banding invisible on a monitor. Send the untouched original to print.

Realistic File Size Targets for a Screenshot or Graphic