How to make a photo smaller in KB for an online form
A photo's size in KB depends on three things, its number of pixels, the JPG quality it's saved at and its format. To get under an upload limit, save it as JPG with fewer pixels (1,200 on the longest side is plenty for most forms) and a quality of 70–85%. On tuul.io/image-compressor/ you can skip the guessing, choose Target file size and a limit such as 100 KB, and each photo gets the best quality that fits, in your browser, without being uploaded.
Why a phone photo is so big
A typical phone camera takes 12-megapixel photos, 4,032 × 3,024 pixels, and saves each one at about 2 to 5 MB as a JPG. An upload form, on the other hand, shows your photo in a box a few hundred pixels wide, and it often wants a file of 50, 100 or 240 KB. That’s 10 to 100 times smaller, and you can get there without the photo looking any worse where it’s used.
The three things that set the size
- Pixels. The file grows with the number of pixels. Halving the width and the height leaves a quarter of the pixels, and in our tests the file came out at about a quarter of the size too. This is the biggest lever, and it costs nothing visible on a form.
- JPG quality. JPG saves space by throwing away detail you can’t easily see. Going from 90% to 70% quality roughly halved the file in our tests. Between 70 and 85% a photo still looks clean; below about 60%, faces and edges get blotchy.
- Format. For photos, JPG is the one to use. PNG keeps every pixel and made our photos 7 to 13 times bigger. HEIC (from iPhones) and WebP are small, but most forms refuse them.
The photo itself matters too. Grass, leaves, gravel and busy patterns are hard to compress; a face against a plain wall is easy. In our tests, four photos with the same settings differed in size by up to four times.
How big a photo comes out
We resized four 12-megapixel photos (a fjord, a pine forest, a dog under a blanket and a lioness) and saved them as JPG at 80% quality:
| Size in pixels | Smallest file | Largest file |
|---|---|---|
| 1,600 × 1,200 | 145 KB | 554 KB |
| 1,200 × 900 | 82 KB | 316 KB |
| 800 × 600 | 40 KB | 142 KB |
| 600 × 450 | 25 KB | 82 KB |
The forest, full of needles and leaves, was always the largest, and the dog against a soft, blurred background the smallest. We measured with a standard JPEG encoder; browsers give similar, though not identical, sizes. Use the table to pick a starting point, then check your own photo.
Typical limits
| Where | Limit |
|---|---|
| US visa application (DS-160) | JPEG, square, 600 × 600 to 1,200 × 1,200 pixels, at most 240 kB |
| UK passport, online | At least 600 × 750 pixels, between 50 KB and 10 MB, not edited |
| Exam, job and government portals | Often 20–50 KB for the photo and 10–20 KB for a signature; the form’s instructions give the exact numbers |
| Gmail | 25 MB of attachments per email |
Read the form’s rules before you start. Some set a minimum as well as a maximum, like the UK’s 50 KB, and passport services usually want the photo unaltered, so only shrink it if the size is actually over the limit, and never edit the face or background.
Get under a size limit in your browser
- Open tuul.io/image-compressor on your phone or computer.
- Add the photo: drag it onto the page, or tap Choose files and pick it. iPhone HEIC photos work too and are saved as JPG.
- Under Compress by, choose Target file size. Under Make each file under, pick the form’s limit (50 KB, 100 KB, 200 KB, 500 KB, 1 MB or 2 MB), or choose Another size and type it.
- Under Largest side, pick a size such as 1024 or 800 px. Fewer pixels leave room for a higher quality, so the photo looks better at the same KB.
- Read the photo’s row. It shows the size before and after and the quality that was used. If even 40% quality was too big, the photo was also made smaller in pixels, and the row says so.
- Download the photo, or all of them as one ZIP file if you did several.
The compressor tries qualities between 40 and 92% and keeps the highest one that fits. It counts a KB as 1,000 bytes, so a file under its 100 KB also passes forms that count 1,024. A photo that’s already under the limit is kept as it is. Nothing is uploaded, and the photo’s metadata, including its GPS location, is removed; no form needs it.
If your photo is a PNG screenshot or scan, set Save as to JPG: PNG keeps every pixel and barely shrinks.
When the form wants exact pixels
Some forms set the shape too, like the US visa’s square photo. Make the size first, then the KB:
- To choose which part of the photo is kept, open tuul.io/crop-image, pick the 1:1 shape and drag the box over your face.
- To set the exact size, open tuul.io/bulk-image-resizer, choose Exact width and height under Resize by, enter 600 × 600, pick Crop to fill the size, and set Save as to JPG. The row shows the new file size.
- If it’s still over the limit, put the result through tuul.io/image-compressor with the target size, and leave Largest side on Keep the size in pixels.
tuul, like Windows, shows sizes with 1 KB as 1,024 bytes. When you resize by hand rather than with a target size, aim a few percent under the limit, because some forms count 1,000.
Without a website
- Windows 11: open the photo in Photos and choose Resize image. You can set the pixels or a percentage and the JPG quality, and Photos shows the new file size before you save.
- Mac: open the photo in Preview and choose Tools > Adjust Size. Enter a smaller width, keep “Resample image” ticked, and the new size is shown at the bottom. File > Export then lets you lower the JPEG quality.
- iPhone and Android: the Photos and Gallery apps can’t save a photo at a set size, so use a browser tool.
What not to do
- Don’t rename a .heic, .webp or .png file to .jpg. The form may accept the name and then reject or garble the file.
- Don’t screenshot the photo to make it smaller. You lose detail and often get a large PNG.
- Don’t push quality below 60% to hit a tiny limit. Shrink the pixels instead; on a form, a 400-pixel photo at 70% usually looks better than an 800-pixel one at 30%.
Sources
- U.S. Department of State: Digital image requirements for visa photos: JPEG, 600 × 600 to 1,200 × 1,200 pixels, at most 240 kB.
- GOV.UK: Photos for passports: at least 600 × 750 pixels, 50 KB to 10 MB, unaltered.
- Gmail Help: Attachment size limits: 25 MB.
- Apple Support: Crop, resize or rotate an image in Preview on Mac.
- Office Watch: Great image resize options now in Windows (May 2024): resizing and saving at a set quality in the Photos app.
Questions
How do I make a photo under 100 KB?
On tuul.io/image-compressor/ choose Target file size and 100 KB, set Largest side to 1024 or 800 px, and add the photo; it gets the best quality that fits. By hand, resize it to about 800 pixels on the longest side and save it as JPG at 80% quality, which gave 40 to 142 KB in our tests; if it's still over, go to 70% or 600 pixels.
How do I reduce a photo to 20 KB or 50 KB?
Make it small in pixels first, then lower the quality. For 50 KB, try 500 to 600 pixels on the longest side at 70% JPG quality; for 20 KB, about 400 pixels at 60 to 70%. On tuul.io/image-compressor/ choose Target file size, then 50 KB or Another size, and it finds the quality for you.
Does making a photo smaller in KB ruin the quality?
Not if you shrink the pixels before you lower the quality. A form shows your photo a few hundred pixels wide, so 1,200 or 800 pixels looks just as sharp there. JPG quality between 70 and 85% looks clean; below about 60%, faces and edges start to look blotchy.
Why did my photo get bigger when I saved it as PNG?
PNG is lossless, so it keeps every pixel exactly and can't throw away detail the way JPG does. For photos that makes files many times bigger; in our tests PNG copies were 7 to 13 times the size of 80% JPGs. Use JPG for photos and PNG for screenshots, logos and signatures with few colours.