How to reduce image size to 40 KB
- Click Choose images or drag photos into the box (you can add several at once).
- The target is already set to 40 KB. Change it if your form needs a different limit.
- Wait a second while each image is compressed, then click Download — or Download all (ZIP) for batches.
What is a 40 KB image used for?
- Job and exam portal photos
- Employee directory pictures
- E-commerce thumbnails
40 KB is a comfortable budget for a small portrait or product thumbnail — detail loss is rarely visible.
Tips for the best quality at 40 KB
- Crop first. Removing empty background gives the remaining pixels more of the size budget.
- Start from the original. Re-compressing an already heavily compressed image adds blockiness.
- Plain backgrounds compress better than busy ones — useful for ID and passport photos.
- Check the official requirements for pixel dimensions too. If a form also needs exact dimensions, use our image resizer with the "Max size" option.
Other target sizes
Frequently asked questions
How do I compress a photo to 40 KB?
Drop your photo into the box above. ImgToSize automatically finds the highest JPEG quality that fits under 40 KB, and only reduces the dimensions if quality alone isn't enough. Then click Download.
Will my image be exactly 40 KB?
It will be at or just below 40 KB — never over. Upload forms reject files that are even 1 byte too large, so we always stay under the limit while keeping as much quality as possible.
Can I compress a PNG or HEIC to 40 KB?
Yes. PNG, HEIC, WebP and AVIF are all accepted. The result is saved as JPG (or WebP), because those formats let us precisely control file size.
Is it safe to use for ID photos and documents?
Yes. Compression runs inside your browser using JavaScript — the image is never uploaded, stored or seen by anyone. You can even disconnect from the internet after the page loads.
My form needs between a minimum and 40 KB. What should I do?
Enter a number slightly below the maximum (for example 38) in the size box. Because we maximize quality, the result lands close to that number rather than far below it.