How to Resize a Photo to 20 KB (Without Making It Blurry)
Resize a photo to 20 KB for an exam or job form: the pixel sizes that fit, the order of steps that keeps it sharp, and fixes if the portal rejects it.
By Awais, Founder and editor-in-chiefPublished
A 20 KB limit sounds impossible when your phone takes 3 to 5 MB photos. It isn’t. The trick is to make the image smaller in pixels first and only then squeeze the file. Do it in that order and a 20 KB photo looks sharp. Do it the other way round and you get a blocky smear.
The quick version: crop the photo to the shape the form wants, resize it to roughly 200 × 230 pixels (or the exact size in the notice), then set 20 KB as the maximum in Compress Image to KB. The rest of this guide explains why that works and what to do when it doesn’t.
Why 20 KB is mostly about pixels
A JPG’s size depends on two things: how many pixels it has and how hard each pixel is compressed. Pixels matter far more.
20 KB is 20,000 bytes, or 160,000 bits. Spread those bits over the image and you get a budget per pixel:
| Image size | Pixels | Bits available per pixel at 20 KB | Likely result |
|---|---|---|---|
| 4,032 × 3,024 (phone photo) | 12.2 million | 0.01 | Unrecognisable |
| 1,200 × 1,600 | 1.92 million | 0.08 | Heavy blocks and smearing |
| 600 × 800 | 480,000 | 0.33 | Soft, visible artefacts on faces |
| 300 × 400 | 120,000 | 1.33 | Acceptable for most forms |
| 200 × 230 | 46,000 | 3.48 | Sharp |
| 140 × 60 (signature) | 8,400 | 19 | Far more than needed |
As a rough rule, a photo saved as a decent-quality JPG needs somewhere around 1 to 2 bits per pixel, more for busy detail and less for plain backgrounds. That’s why exam boards that set a 20 KB limit also ask for small dimensions. They know the two go together.
So if a form says “maximum 20 KB” and nothing about pixels, aim for about 300 × 400 px or smaller. If it does give pixels, use exactly those.
Step by step: a photo under 20 KB
- Read the notice. Write down three numbers: the pixel size (for example 200 × 230), the KB range (for example 10–20 KB or 20–50 KB) and the format (almost always JPG or JPEG).
- Crop to the right shape. Open Crop Image and type the exact pixel size, or a matching ratio. For 200 × 230, that’s a portrait shape slightly taller than wide. Keep your face centred with a little space above the head.
- Resize to the exact pixels. In Resize Image, type the width and height. Because you cropped to the right ratio, nothing gets stretched.
- Compress to 20 KB. In compress image to 20KB the target is already set; in Compress Image to KB, choose 20 KB (or Custom and type the number). The tool searches for the highest quality that still fits and never goes over.
- Check it at 100%. Open the result and zoom in on the eyes. If the face edges look blocky, go back to step 3 and use slightly fewer pixels.
Everything above runs inside your browser. Your photo isn’t uploaded anywhere, which matters for ID scans and documents with your name on them.
Step by step: a signature under 20 KB
Signatures are the easy case. They are mostly white space, so they compress very well.
- Sign in black ink on plain white paper. Blue ink and lined paper both add colour noise that costs bytes.
- Photograph it straight from above in daylight, with no shadow from your phone.
- Crop tightly, leaving a small white margin around the ink.
- Resize to the size in the notice. 140 × 60 px is common in Indian bank exam notices.
- Compress to the KB range.
A typical cropped signature at 140 × 60 px lands well under 20 KB even at high quality. If it’s over, the background probably isn’t white. Brighten the photo or rescan it on whiter paper.
When the form says “10 KB to 20 KB”
Some notices set a minimum as well as a maximum. A small, clean signature can easily come out at 6 KB, and the portal then rejects it as “too small”.
To push a file up into the range without changing how it looks:
- Use the full pixel size allowed. If the notice says “up to 140 × 60”, don’t send 100 × 43.
- Raise the quality. In the compressor, set the target to the top of the range (20 KB). It uses the best quality that fits, so the file grows towards the limit.
- Don’t add a border or padding to bulk the file up. Many portals check the dimensions as well as the size.
Why the portal still rejects your file
| Error message (or symptom) | Likely cause | Fix |
|---|---|---|
| “File size exceeds limit” but your phone shows 20 KB | Your phone rounds the size down, so the file is really a few bytes over | Make the file with a tool that measures exact bytes. Ours counts 1 KB as 1,000 bytes, so the result passes on portals that count 1,024 too |
| “Invalid file type” | The file is PNG, HEIC or WebP renamed to .jpg | Re-save as a real JPG; the compressor always outputs JPG |
| “Invalid dimensions” | Pixels don’t match | Resize to the exact numbers in the notice |
| Upload works but the preview is sideways | Rotation is stored as a hidden tag | Re-save the image; good tools apply the rotation |
| Photo rejected after review | Background, lighting or glasses | Retake against a plain wall in daylight |
iPhone photos are HEIC by default. If your file is HEIC, convert it first with HEIC to JPG, or the form may refuse it even after you rename it.
Phone or computer: which is easier?
Both work the same way in the browser. On a phone, the hard part is usually finding the file afterwards. On Android, compressed images go to the Download folder. On iPhone, Safari saves them in Files > Downloads, and many forms let you pick from there with Choose File. If your form only offers Photo Library, open the downloaded JPG in Files, tap Share and choose Save Image first.
Do you need exactly 20 KB?
No. “Maximum 20 KB” means anything from the minimum (if there is one) up to 20 KB passes. A sharp 14 KB photo is better than a blurry 19.9 KB one. Don’t chase the exact number unless the notice gives a range and you’re below it.
If you need a bigger target, such as 50 KB or 100 KB, the steps are identical. Our longer guide on reducing image size in KB lists the photo and signature rules from several real exam notices. For passport-style photos with set head sizes and background colours, start with the passport photo maker.
FAQ
How do I reduce a photo to 20 KB on my phone?
Open Compress Image to KB in Chrome or Safari, pick 20 KB, set a maximum width and height if the form gives one, and choose the photo. The tool resizes and compresses it on your phone and saves a JPG to your downloads.
What pixel size is a 20 KB photo?
There is no fixed answer, because file size depends on detail as well as pixels. In practice, around 200 × 230 px to 300 × 400 px gives a sharp photo under 20 KB. Larger images need such heavy compression that faces turn blocky.
Is 20 KB the same as 0.02 MB?
Yes, if 1 MB is counted as 1,000 KB. Some systems use 1,024, which makes 20 KB about 0.0195 MB. Aim a little under the limit to be safe.
Why does my 20 KB photo look blurry?
It was probably compressed while still large. Resize it to the form’s pixel size first, then compress. Fewer pixels means each one can keep more detail.