More about PNG compression
PNG compression is lossless by definition - the DEFLATE algorithm inside the format rewrites pixel runs and palette indexes more efficiently without discarding a single bit of image data. A typical 24-bit PNG straight out of Photoshop or Figma carries unused alpha channels, redundant gAMA chunks, and a sub-optimal filter strategy that pngcrush, zopflipng, or oxipng can squeeze out for roughly 10-40% savings depending on content. UI screenshots and flat illustrations compress best; photographic PNGs improve less because pixel entropy is already high.
The biggest single win for PNG size is dropping from 24-bit truecolor to an 8-bit indexed palette when the image uses fewer than 256 unique colors - common for logos, icons, and game sprites. Posterized PNG-8 with a quantized palette is technically lossy at the indexing step but visually identical for flat-color art, and the resulting file is often 60-75% smaller than the truecolor source. Tools like pngquant and TinyPNG default to this hybrid approach. For lossless-only workflows stick with oxipng or zopflipng.
If your final destination is the web and you can drop PNG entirely, WebP lossless typically beats optimized PNG by another 20-30%, and AVIF goes further still on photographic content. Compress PNG when you specifically need the format for transparency support in legacy browsers, asset pipelines that reject WebP, app icons (iOS and Android still require PNG), or print workflows expecting RGBA. For everything else convert to WebP and serve PNG only as a fallback.
When you'd use this
You typically reach for Compress PNG when a PNG file is too large for its destination. Common situations include:
- Email attachments – Gmail caps at 25 MB, Outlook at 20 MB; a single phone photo is often 6–10 MB.
- Upload portals – real-estate listing sites, school portals and insurance forms commonly cap each file at 2–5 MB.
- Web performance – compressing hero images and gallery photos directly improves Core Web Vitals scores and reduces bandwidth costs.
- Storage – when archiving thousands of photos to a cloud drive, a 70–80% size reduction at quality 85 is invisible to the eye.
How to do it in jpg.now
- Open the Compress PNG tool on jpg.now.
- Drag your PNG file onto the drop zone, or click Select files. You can drop a whole folder of files at once.
- Pick a compression preset (Small, Balanced, High, Max) or move the quality slider for fine-grained control. Higher quality = larger file.
- Click Compress. The job runs on our server and finishes in a few seconds for typical photos.
- Download the result. Files stay in storage for 24 hours and are then permanently deleted.
The entire flow is free for the first 10 jobs per day with no signup required. A free account doubles that quota; a premium plan removes the limit entirely.
Tips and common pitfalls
- Quantize to PNG-8 with pngquant for flat-color UI work - 256 colors is invisible for icons, buttons, and illustrations, and saves 60-75% versus 24-bit.
- Strip ancillary chunks (tEXt, gAMA, sRGB, iCCP) with oxipng --strip safe - they add 200-800 bytes per file and rarely render anything visible.
- For sprite sheets and tilemaps, run zopflipng with --iterations=15 - it spends extra CPU finding better filter combinations and beats default DEFLATE by another 8-12%.
- Don't compress PNGs that will be re-saved later in Photoshop or Figma - the editors expand them back to uncompressed RGBA on load anyway, so optimize only at the final export step.
- If transparency isn't needed, convert to JPG at quality 90 instead - photographic PNGs are typically 4-6x larger than the equivalent JPG with no visible difference.