The fastest way: compress to a target size
- Open the Image Compressor and drop in your photo. It's processed in your browser, so ID photos and documents aren't uploaded.
- Type the target, for example 100 KB. If you're not sure how the form counts kilobytes, set 1 KB = 1,000 bytes. It's the stricter of the two.
- Choose JPEG as the output for photos. Use WebP only if the form accepts it.
- Leave Shrink the dimensions if quality alone can't reach the target switched on, and set a maximum width, such as 1600 px, if the form gives one.
- Download the result. The exact size is shown in bytes, and if the target can't be met at a usable quality, the tool tells you instead of quietly handing you a broken file.
Why some photos won't fit: the pixel budget
A file size limit is really a budget of bits per pixel. 100 KB is 100,000 bytes, or 800,000 bits. Divide that by the number of pixels, and you get how much data each pixel can have:
| Dimensions | What it is | Pixels | Bits per pixel at 100 KB |
|---|---|---|---|
| 4,032 × 3,024 | 12 MP phone photo | 12,192,768 | 0.07 |
| 1,920 × 1,440 | Full HD width | 2,764,800 | 0.29 |
| 1,600 × 1,200 | Large web image | 1,920,000 | 0.42 |
| 1,200 × 900 | Typical upload size | 1,080,000 | 0.74 |
| 800 × 600 | Small web image | 480,000 | 1.67 |
As a rough guide, a detailed photo saved as JPEG at good quality needs somewhere around 1–2 bits per pixel. Below about 0.5, blocky artifacts start to show. So a full 12-megapixel phone photo, at 0.07 bits per pixel, can't hit 100 KB without looking terrible. At 1200 × 900, though, there are 0.74 bits per pixel to spend, enough for a clean result. The lesson: reduce the dimensions first, then the quality. Most upload forms display images much smaller than a phone captures them anyway.
Choosing the format
| Format | Best for | At 100 KB |
|---|---|---|
| JPEG | Photos and scans. Accepted everywhere. | The safe default. Easily fits 1200 px photos. |
| WebP | Photos and graphics on the web | Usually smaller than JPEG at the same quality, but some forms reject it |
| PNG | Screenshots, logos, line art | Lossless, so photos rarely fit. Fine for simple graphics. |
If the original has a transparent background, like a logo, saving it as JPEG fills the transparent areas with a background color (white by default). Use the Image Format Converter to switch formats in bulk, or let the compressor convert as it goes.
Common targets and settings that work
- Profile or ID photo, 20–50 KB: crop to the exact dimensions the form asks for (often around 600 × 600 px for a square photo), then compress. Use the Image Resizer & Cropper for the crop.
- Job or school application photo, 100 KB: 1000–1200 px on the long side, saved as JPEG.
- Document scan, 200 KB: about 1600 px on the long side keeps text readable. Grayscale scans compress better than color ones.
- Website image, under 150 KB: size it to the width it will actually be displayed at (often 1200–1600 px), and use WebP if your site supports it.
Doing it by hand
No target-size tool handy? Use any editor's "Export" or "Save for web" option. Set the long side to about 1200 px, export as JPEG at quality 80, and check the size. If it's over, try 70, then 60. Below 50, faces and text start to suffer, so shrink the dimensions again instead. Repeat until it fits. The compressor runs this same search automatically and stops at the highest quality that fits.
iPhone photos (HEIC)
iPhones save HEIC files by default, and many upload forms reject them outright. Convert to JPG first with the HEIC to JPG Converter, then compress. For more on why, see HEIC vs JPG.
Troubleshooting
- The photo comes out sideways: phone photos store their rotation as an EXIF tag. The compressor applies it before encoding, so the result is upright.
- The result is blurry: you've hit the pixel budget. Lower the dimensions rather than the quality.
- The form still rejects the file: check the required format (JPG vs JPEG is the same thing, but WebP and PNG may not be accepted), the pixel dimensions, and leave a few KB of margin.