Reduce Image Size in KB — Free, No Signup
Reduce an image to a specific size in kilobytes. The tool shows the before and after size after every run, so you can nudge the quality slider until the number fits whatever limit the form is enforcing.
How to do it
- Drop the image onto the upload box.
- Drag the quality slider down and watch the KB readout update.
- Stop when the number is just under your target — the preview shows what that quality actually looks like.
- Download the file at that size.
Why forms demand an exact KB figure
Government portals, exam boards, job applications, and visa systems almost all specify a hard ceiling — 100 KB, 200 KB, sometimes 50 KB for a passport photo. The limit exists because these systems store millions of documents and were often designed years ago against tight storage budgets. The form rarely explains how to meet it, and rejecting an upload without saying by how much you missed is depressingly common. Being able to see the resulting size before you submit is the whole point of doing this yourself rather than guessing.
Getting to a target size
Work downwards. Start at quality 70, look at the resulting size, and adjust. Roughly speaking, dropping from 70 to 50 cuts the file by another third, and 50 to 30 cuts it by about half again. If quality 30 still will not fit, the problem is resolution rather than encoding — a 12-megapixel photo simply cannot become a good-looking 100 KB file. Resize the long edge to 1000 or 1200 pixels first, then compress; you will hit the target at a much higher quality setting and the result will look far better.
Passport and ID photo targets
The typical requirement is a JPEG between 20 and 50 KB at around 600 by 600 pixels. Two things make this easier than it sounds. First, ID photos are a face against a plain background, which is exactly the content JPEG compresses most efficiently. Second, the small pixel dimensions do most of the work before compression even starts. Resize to the specified dimensions first, then compress at quality 70 and check — you will usually be inside the range immediately, and you can raise the quality if you have headroom left.
Why the size varies so much between photos
Two photos with identical dimensions and identical quality settings can differ threefold in file size. Detail is the reason. A portrait against a plain wall compresses to a fraction of what a photo of foliage, gravel, or a crowd does, because the encoder has to describe every leaf and pebble. Noise from a low-light shot has the same effect. If a photo stubbornly refuses to shrink, it is usually busy or grainy rather than badly compressed, and reducing the dimensions is the reliable lever.
What comes out
Output is always JPEG, which is what these forms almost always want. Quality is clamped between 10 and 95. Input can be JPG, PNG, or WebP up to 5 MB, and transparency is flattened onto white. Everything runs in your browser, which matters here more than usual — identity documents and application photos never leave your device.
Frequently asked questions
How do I get an image under 100 KB?
Start at quality 70 and check the resulting size. If it is still too large, resize the long edge to 1200 pixels first, then compress again — resolution matters more than quality below 200 KB.
How do I compress a passport photo to 50 KB?
Resize to the required dimensions first, usually around 600 by 600, then compress at quality 70. Plain backgrounds and small dimensions together usually land inside 20 to 50 KB.
Why do two photos at the same quality have very different sizes?
Busy or noisy images cost more bits to encode. A portrait against a plain wall compresses to a fraction of a photo of foliage at identical settings.
Can I set the target size directly?
Not as a number. You set quality and the tool shows the resulting size, so you adjust and re-run. Two or three attempts normally land on any target.
Does the tool change the pixel dimensions?
No, compression only changes the encoding. Use the image resizer first if you also need smaller dimensions, which is usually the faster route to a very small target.
Is my ID document uploaded anywhere?
No. The image is processed entirely inside your browser and never sent to a server, which is exactly why this matters for identity documents.