The fastest way to reduce PNG size in Affinity Photo 2

Export your PNG with fewer colors instead of trying to compress an already-saved file. In Affinity Photo 2, open your image, go to File > Export, choose PNG as the format, then click the Options button. Under Color Depth, change from 32-bit (which includes transparency information for every pixel) to 8-bit if your image doesn't need smooth gradients or many colors. This single change often cuts file size in half or more.

If you need to keep 32-bit color depth because your image has gradients or many colors, turn on Interlacing in the same Options panel — it doesn't reduce file size but makes the image appear faster as it loads. The real savings come from reducing color depth, not from interlacing or compression settings.

Key Takeaways

  • PNG files shrink most when you reduce color depth from 32-bit to 8-bit, which works best for images with solid colors or limited palettes.
  • Affinity Photo 2's export options let you choose color depth before saving, so you don't have to re-export multiple times to find the right balance.
  • Interlacing makes a PNG load progressively in web browsers but does not reduce the file size itself.
  • If your image has smooth gradients or photographs, 32-bit color depth is usually necessary and color reduction will make banding visible.

When 8-bit color depth works and when it doesn't

8-bit PNG uses a palette of up to 256 colors, which is plenty for logos, icons, screenshots, and solid-color graphics. If your image is a flat design with distinct color blocks, switching to 8-bit will shrink the file noticeably with no visible loss. You can see the difference when ready in the export preview — if the image looks the same, 8-bit is safe.

Photographs, images with gradients, or artwork with many color variations need 32-bit depth. Forcing these into 8-bit creates visible banding — flat stripes of color where smooth transitions should be. If you see banding in the preview, switch back to 32-bit. The file will be larger, but it will look correct.

Reducing dimensions if color depth doesn't help enough

If you've already switched to 8-bit and the file is still too large, the image itself is probably bigger than it needs to be. Before exporting, go to Image > Resize and reduce the width and height. Cutting the dimensions in half reduces file size to about one-quarter, because you're removing pixels, not just compressing them.

Know what size you actually need before you resize. If the PNG will display at 400 pixels wide on a website, exporting at 800 pixels wide wastes space. If it's a print file or will be enlarged, keep the larger dimensions. Resizing is permanent once you export, so do it only if you're sure the smaller size is what you need.

Using Affinity Photo 2's compression slider

In the PNG export options, there is a Compression Level slider that ranges from 0 (no compression) to 9 (maximum compression). Moving this slider to 9 makes the file smaller without changing how the image looks, but the difference is usually small — often 5 to 15 percent. Compression takes longer to process, so if you're exporting many files, a middle setting like 6 or 7 is a reasonable trade-off.

Compression only works on the data structure of the PNG, not on the image content itself. It cannot replace reducing color depth or dimensions. If you've already switched to 8-bit and the file is still large, increasing compression will help a little, but resizing the image will help much more.

Comparing PNG to other formats when size matters most

PNG is lossless, meaning it keeps all the original image data. If file size is critical and the image is a photograph or has many colors, JPEG is usually smaller because it discards some color information in a way the human eye doesn't notice. Affinity Photo 2 exports JPEG the same way — go to File > Export, choose JPEG, and adjust the quality slider. A quality setting of 75 to 85 is often invisible to viewers but produces a much smaller file than PNG.

JPEG doesn't support transparency, so use it only for images that don't need a transparent background. For logos, icons, or anything with a transparent area, PNG is the only choice. For photographs or complex artwork without transparency, test both formats at the size you need and pick the one that looks right and is small enough.

Batch exporting multiple PNGs with the same settings

If you have many images to export with the same color depth and compression settings, use File > Export As to set your options once, then use File > Batch Export to explore those settings to multiple files at once. This saves time and ensures consistency across all your exports.

Batch export works on multiple artboards within a single document or on multiple separate documents. Set up your first export with the color depth and compression you want, then Affinity Photo 2 will remember those settings for the batch. You can still override individual files if one needs different settings.

Frequently Asked Questions

What's the difference between 8-bit and 32-bit PNG?

8-bit PNG uses a palette of up to 256 colors and is smaller. 32-bit PNG stores full color information plus transparency for every pixel and is larger. Use 8-bit for logos and icons, 32-bit for photographs and gradients.

Does interlacing make PNG files smaller?

No. Interlacing makes the image appear gradually as it loads in a web browser, but the file size stays the same. It's useful for web images but doesn't reduce the read size.

Should I always use maximum compression?

Maximum compression (level 9) saves 5 to 15 percent compared to no compression, but takes longer to process. For most uses, level 6 or 7 is a good balance. The bigger savings come from reducing color depth or image dimensions.

Can I convert a PNG to JPEG to make it smaller?

Yes, if the image doesn't need transparency. JPEG is usually smaller than PNG for photographs and complex images. Open the PNG in Affinity Photo 2, go to File > Export, choose JPEG, and adjust the quality slider. Lower quality means smaller file size but more visible loss.

What if I need the PNG to stay 32-bit but still be smaller?

Reduce the image dimensions before exporting, or increase the compression level to 9. If the image is a photograph, consider JPEG instead. If it's artwork with transparency, you may have reached the smallest size PNG can achieve without losing quality.