What 100 KB looks like
A hundred kilobytes is a comfortable budget for a photo on a page that needs to load quickly on a phone. The test photo came out at 97 KB with JPEG quality 56 and all of its 2000 x 1333 pixels. The screenshot reached quality 40 at 99 KB, and the illustration stopped at quality 92.
That last result shows how the search ends. When a file already fits at quality 95, the tool stops there, because going higher makes the file much bigger for almost no visible gain. You get a file under 100 KB, not a file of exactly 100 KB.
| Test image | Original | Result | JPEG quality | Pixels | Time |
|---|---|---|---|---|---|
| Photo | 694 KB | 97 KB | 56 | 2000 x 1333 | 3.5 s |
| 12 MP photo | 1.81 MB | 99 KB | 40 | 2483 x 1655 (from 4000 x 2667) | 7.8 s |
| Screenshot | 46 KB | 94 KB | 92 | 1600 x 900 | 2.2 s |
| Illustration | 94 KB | 81 KB | 95 | 1200 x 1200 | 392 ms |
Test images are synthetic files made by this project: a 2000 x 1333 landscape photo, a 1600 x 900 interface screenshot and a 1200 x 1200 transparent illustration. The 12 MP photo is the same photo scaled up to 4000 x 2667, the size a phone camera saves. Quality is lowered first and the image is only scaled down when quality alone cannot reach the target. A JPEG that is already under the target is left as it is. Timings: one thread of WebAssembly on Node v22.23.4, Intel(R) Xeon(R) Processor @ 2.10GHz, 2 cores, measured 2026-10-31. Other devices will differ.
Where 100 KB helps
- Product and blog photos that should load fast on mobile data.
- Attachments when a mailbox or portal caps the total size.
- Upload forms that reject anything larger than 100 KB.
Choosing the format
This page makes a JPEG, because it opens everywhere and forms accept it. If your site serves modern formats, switch the output to WebP under Save as. For the same 100 KB, WebP in the home page test used quality 50 against 56 for JPEG, with a PSNR of 33.8 dB against 33.9 dB. The JPG to WebP page has the details.
Keep the original
A 100 KB file is a finished copy, not a master. Keep your original for later edits, and make the small version from it each time you need one.
A good order of steps
- Cut away what you do not need with the crop tool.
- Set the pixel size you will actually show with resize. A picture displayed 600 pixels wide gains nothing from 3000 pixels.
- Compress to 100 KB here and compare with the original at 100% zoom.
- If detail you care about looks soft, raise the target to 150 KB, or lower the pixel size and try again.
Doing the pixel size first matters most. Fewer pixels leave more bytes for each one, so the same 100 KB buys a higher quality.
Reading the result
The result line gives the original size, the new size, the percentage saved and the JPEG quality the search settled on. Above 80 a photo usually looks clean. Between 60 and 80, look closely at skies and skin. Below 50 the picture is carrying a lot of compression, and a smaller pixel size will probably serve you better than more squeezing.
A kilobyte here is 1000 bytes. The result is always at or under 100,000 bytes, so it also passes a check that counts 1024 bytes to the kilobyte.
Questions
Will the picture be exactly 100 KB?
No. The result is the best quality that fits under 100 KB, so it is usually a little smaller.
Why not just resize it?
You can. Resizing is the stronger lever for photos, and the <a href="/resize-image/">resize page</a> does it. Many people combine the two.
Can I compress a batch to 100 KB?
Yes, within the daily limit of 10 images. The <a href="/bulk-image-converter/">bulk page</a> adds a ZIP download.
Does it remove my location data?
Yes, by default. Metadata removal is on and you can switch it off in Advanced settings, under Metadata.