To get an image under 20 KB, make it smaller in pixels first, then lower the JPEG quality. Resize the photo to about 300 px wide, then compress it to JPEG at around 60–70% quality, and check the size. For 50 KB, around 600 px wide at 70% usually works. You can do both steps free in your browser with ToolBrainy.
Exam registrations, job portals, scholarship forms and government sites love tight upload limits: “photo between 10 and 20 KB”, “signature under 10 KB”, “max 50 KB”. A phone photo is often 2–5 MB, more than 100 times too big. Here’s how to get it down without making it unrecognisable.
Why a quality slider alone isn’t enough
File size depends on two things: how many pixels the image has and how heavily each one is compressed. A 4000 × 3000 phone photo has 12 million pixels. Even at very low quality, that’s too much data for 20 KB, and the result looks blocky.
Cutting the pixels does most of the work. A 300 × 400 image has just 120,000 pixels, 1% of the original, so it fits under 20 KB at a quality where it still looks clean.
Step by step: resize an image to 20 KB
Step 1: Crop to what the form wants
Most forms want your face and shoulders on a plain background, not the whole room. Use the Crop Image tool to cut out everything else. If the form says “3.5 × 4.5 cm”, that’s a 7:9 ratio, slightly taller than wide.
Step 2: Reduce the pixel size
Open the Image Resizer, add your photo and type a width, keeping Lock aspect ratio ticked:
- Under 20 KB: 300 px wide (or the exact pixel size the form gives, such as 200 × 230).
- Under 50 KB: 500–600 px wide.
- Under 100 KB: 800–1000 px wide.
Set the output format to JPEG and download.
Step 3: Compress to the exact limit
Open the Image Compressor, add the resized image, choose JPEG and set Quality to about 70%. The tool shows the new file size:
- Still too big? Lower the quality in steps of 5–10%.
- Below 50% and still too big? Go back to Step 2 and use a smaller width. That looks better than crushing the quality.
- Too small? Some forms have a minimum, like 10 KB. Raise the quality until you’re inside the range.
Step 4: Check it like the examiner will
Open the final image at full size. Is your face clear, with no blocky patches around your eyes and hair? Is the background plain? If so, upload it.
Starting settings by target size
| Target | Width | JPEG quality | Typical use |
|---|---|---|---|
| Under 10 KB | 140–200 px | 60–70% | Signatures, small ID photos |
| 10–20 KB | 200–300 px | 60–75% | Exam and job form photos |
| Under 50 KB | 500–600 px | 65–75% | Profile photos, ID scans |
| Under 100 KB | 800–1000 px | 70–80% | Documents, certificates |
These are starting points. Busy backgrounds, grain and low light make files bigger, so always go by the size the tool shows.
Signatures: the easiest file to get tiny
Signature uploads often need to be under 10 KB and around 140 × 60 px. Sign in black ink on white paper, photograph it in daylight, crop tightly around the signature, resize to the requested pixels, then compress to JPEG at about 70%. A clean signature usually comes in at just a few kilobytes. If the paper looks grey, the Background Remover can help clean it up first.
Common mistakes
- Uploading a PNG. PNG is great for logos and screenshots, but photos come out much bigger than JPEG. Use JPEG (.jpg) unless the form asks for something else. Not sure why? Read JPG vs PNG vs WebP.
- Using WebP when the form wants JPG. WebP is smaller, but many government portals only accept .jpg or .jpeg.
- Compressing the same file again and again. Each pass loses more detail. Go back to the original and start over with a smaller width.
- Stretching the photo. Typing both width and height with the aspect lock off distorts faces. Crop to the right shape first, then resize.
Frequently asked questions
How do I reduce a photo to 20 KB on my phone?
Open the ToolBrainy tools in your phone’s browser. They work on Android and iPhone with nothing to install. Crop, resize to about 300 px wide, then compress to JPEG at 60–70%.
Will my photo look bad at 20 KB?
Not if you shrink the pixels first. A 300 px photo at 70% quality looks clean at the size forms display it. It only looks bad if you keep the full resolution and push the quality very low.
Is it safe to upload my ID photo to an online tool?
The ToolBrainy image tools process files in your browser, so your photo isn’t uploaded to a server.
What’s the difference between KB and pixels?
Pixels are the image’s dimensions (for example 300 × 400). KB is the file size on disk. Forms often specify both, and you need to meet both.
Can I compress several photos at once?
Yes. The Image Compressor and Image Resizer both accept multiple images and let you download them all together.
The short version
Crop → resize to about 300 px wide (600 px for 50 KB) → compress to JPEG at 60–70% → check the size → upload. Start with the Image Resizer, then finish in the Image Compressor. Need a PDF under a limit instead? See how to compress a PDF to 100 KB.
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