How to compress an image to 300KB
- Select Choose files, or drop a JPG, PNG or WebP image on the box.
- The tool aims for under 300KB, which is 307,200 bytes here. It tests quality levels from 95 down to 40 percent and keeps the sharpest result that fits.
- If 40 percent is still too big, it shrinks the width and height by 15 percent at a time until the file fits.
- Select Download. The result ends in
-compressed, so your original is untouched.
Where a 300KB limit comes from
A 300KB ceiling appears on upload fields for documents, listing photos and attachments where a few images are expected. It is roomy enough for a full-width web photo.
What 300KB means in pixels
300KB is 307,200 bytes, or 2,457,600 bits. Divide that by the number of pixels and you get the bits each pixel can use. Photos look fine at about 1.5 bits per pixel or more, and the table shows how common sizes fare at 300KB.
| Picture size | Pixels | Bits per pixel | At 300KB |
|---|---|---|---|
| 640×480 | 307,200 | 8.00 | comfortable, the tool keeps all pixels |
| 1024×768 | 786,432 | 3.13 | comfortable, the tool keeps all pixels |
| 1600×1200 | 1,920,000 | 1.28 | fine for photos |
| 4000×3000 | 12,000,000 | 0.20 | too tight, the tool shrinks the picture |
At 1.5 bits per pixel, 300KB holds a picture of about 1,478×1,109 pixels in a 4:3 shape (1,639,102 pixels). At 300KB an image around 1600 pixels wide keeps fine detail. A 12 megapixel phone photo is reduced to about that width. Graphics with flat colour and text, such as screenshots, usually fit with little visible change.
Tips
- If you only need to get under 300KB once, skip resizing. The tool shrinks the size for you when quality alone is not enough.
- Screenshots in PNG are saved as WebP here, which is typically much smaller and still sharp.
- For a hard pixel requirement, use the image resizer first.
- See also: compress to 200KB, compress image to 500KB, compress image to 150KB, image resizer.
Your images stay on your device. Nothing is uploaded, and there is no sign-up.