How to compress image to 300KB
300 KB is enough for a sharp 1600–1920 px photo, the size most full-width website images are shown at. Drop your image to get the best JPG or WebP under 300 KB, without uploading it.
- Drop, paste or choose your image (JPG, PNG, WebP, GIF, BMP or AVIF). A sample photo is loaded so you can try it first.
- The target is preset to 300 KB. Change it, or pick another preset, if your form asks for something different.
- Optionally choose an output format and a maximum width or height.
- Check the side-by-side preview and the exact byte count, then click Download.
What fits in 300 KB (measured)
| Photo | Format | Result | Quality | File size |
|---|---|---|---|---|
| Landscape, 3840×2743 | JPEG | 2167×1548 px | 45 | 306,379 bytes |
| Landscape, 3840×2743 | WebP | 2341×1672 px | 42 | 299,118 bytes |
| Landscape, 3840×2743, max 1920 px | JPEG | 1920×1372 px | 60 | 305,467 bytes |
| Landscape, 3840×2743, max 1600 px | JPEG | 1600×1143 px | 77 | 302,838 bytes |
| Portrait, 2848×4272 | JPEG | 1538×2308 px | 43 | 301,272 bytes |
Measured with this tool in Chrome on two test photos: a detailed 10.5-megapixel landscape (3840×2743, 3.4 MB) and a 12-megapixel portrait-orientation photo (2848×4272, 3.7 MB). Your results depend on how much detail the photo has; plain backgrounds compress far better.
How the compressor hits an exact size
The tool decodes your image in the browser, then re-encodes it with the browser's own JPEG, WebP or PNG encoder. For JPEG and WebP it runs a binary search on the quality setting — usually 6 to 10 test encodes — and keeps the highest quality whose file is at or under your target. If even a low quality (40%) is still too large, it reduces the pixel dimensions by the amount the byte count suggests, then searches quality again, so you get the largest picture that fits rather than a blocky one. PNG is lossless, so for PNG only the dimensions change. If your file is already under the target and you keep the same format, the original is returned untouched.
Everything happens on your device with the Canvas API; nothing is uploaded, and the re-encoded file does not carry the original EXIF metadata (camera, GPS).
Frequently asked questions
How big is a 300 KB photo in pixels?
With no size cap, our detailed 10.5 MP test landscape fit at 2167×1548 px (JPEG quality 45), and as WebP at 2341×1672 px. Capped at 1920 px wide it fit at quality 60, and at 1600 px wide at quality 77.
Is 300 KB good for a website hero image?
Yes. A 1600–1920 px JPEG or WebP around 200–300 KB is a common target for full-width images: sharp on laptops and quick to load. Pick the 1920 px or 1600 px preset so the bytes go to quality rather than extra pixels nobody will see.
How do I compress a scanned document photo to 300 KB?
Drop the scan, keep JPEG, and the tool fits it under 300 KB. Text stays readable best at a smaller width with higher quality, so try the 1600 px preset if letters look blocky.
Are my images uploaded to a server?
No. Compression runs entirely in your browser using the Canvas API. The image never leaves your device, which also makes it safe for ID photos and signatures.
Is it free?
Yes. Compressing one image at a time is free with no signup and no watermark. Gridloom Pro adds batch compression of many images with a single ZIP download.