Image Format & Compression Size Savings Estimator
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This tool answers a question every developer and designer runs into: which format and quality setting should this particular image use? Rather than relying on rules of thumb, it takes your uploaded image and genuinely re-encodes it through the browser canvas at each format and quality you select, then reports the actual byte size of each result. That matters because compression behaviour depends heavily on image content — a flat illustration and a detailed photograph respond very differently to the same JPEG quality setting, and generic advice frequently points the wrong way. PNG is lossless and keeps transparency but is large for photographic content. JPEG is usually smallest for photos but cannot store transparency. WebP typically lands well below JPEG at comparable quality while still supporting transparency. Move the quality slider and watch the measured sizes update, so you can find the exact point where further compression stops being worth the visible loss. When you have picked a winner, download it directly. Every encode happens locally in your browser, so your image is never uploaded. Upload an image below to compare formats.
Features
- Re-encodes your actual image, so sizes are measured not estimated
- Compares PNG, JPEG, and WebP side by side
- Quality slider for the lossy formats with live size updates
- Shows the saving against the original file
- Download whichever result you pick
- Drag and drop, click to browse, or paste from the clipboard
- Runs entirely client-side — nothing is uploaded
Why use this image compression & format size estimator?
- Instant estimates with no waiting on real compression
- Fully private since no actual image file is needed
- Based on realistic, well-established format compression behavior
- Simple input-and-compare workflow
- Free with unlimited comparisons
Frequently asked questions
How much smaller is WebP than JPEG?
WebP typically produces files 25-35% smaller than JPEG at similar visual quality, though actual savings vary by image content.
Is AVIF smaller than WebP?
AVIF often compresses even further than WebP, sometimes by an additional 20-30%, though it takes longer to encode and has narrower older-browser support.
Does this tool actually compress my image?
No, this is an estimator based on typical format compression ratios; use the image compressor tool to actually shrink a file.
Why do PNG files compress less than JPEG?
PNG uses lossless compression to preserve every pixel exactly, while JPEG uses lossy compression that discards some detail for much smaller files.
Should I use WebP or AVIF for my website?
WebP has broader browser support and is a safe default, while AVIF offers better compression if your audience uses modern browsers and you can provide a fallback.
Are the estimated savings exact?
No, they're approximations based on typical compression behavior — actual results depend on image content, detail level, and the specific encoder settings used.
Do I need to upload my image to get an estimate?
No, you only need to enter the current file size and format — no actual image file is required.
From the blog
WebP vs PNG vs JPG: Which Should You Use?
WebP vs PNG vs JPG compared head to head on file size, transparency, quality and browser support — plus a simple rule for picking the right one every time.
PNG vs JPG: When Transparency Decides for You
PNG vs JPG explained through the one difference that settles most cases — the alpha channel. Covers transparency, matting, file size, screenshots and quality loss.
AVIF vs WebP: The Next Format War
AVIF vs WebP compared honestly: compression gains, browser support, encode speed and transparency — plus when the extra 20–30% is worth the added complexity.