How to reduce an image's file size without ruining it
Upload limits are everywhere – applications, government portals, email, marketplaces. Here's what actually makes an image file big, and the order of steps that keeps it looking good.
What makes an image file big
Four things decide how many kilobytes a picture needs:
- Number of pixels. A 12-megapixel phone photo has twelve million of them. Halve the width and height and you keep only a quarter.
- Format. JPG, WEBP and AVIF throw away detail you barely notice; PNG keeps every pixel and is much bigger for photos.
- Quality setting. Lowering JPG quality from 95 to 80 often halves the file with hardly any visible difference.
- Content. Grass, gravel and noisy low-light shots are expensive. A plain wall or a blue sky is cheap.
The right order of steps
- Crop. Remove what isn’t needed – borders, background, empty desk around a document. It’s free quality.
- Use a sensible pixel size. Few forms need more than 1,200–2,000 pixels on the long side. Fewer pixels means more kilobytes per pixel and a sharper result.
- Choose JPG for photos and scans. It’s accepted everywhere and gives the best size for the quality.
- Compress to the limit. Let a tool find the highest quality that fits, rather than guessing a quality number.
Compress to an exact size does steps 2 to 4 automatically: it searches for the best quality under your limit and only reduces the pixel size when quality alone isn’t enough.
What fits in common limits
| Limit | Typical use | What fits well |
|---|---|---|
| 50 KB | Signatures, small ID photos | A small portrait or a signature on a white background |
| 100 KB | Application portals, profile photos | A portrait at around 800–1,200 px |
| 200 KB | Forms, listings | A sharp photo at around 1,200–1,600 px |
| 500 KB | Document uploads | A readable A4 scan or a detailed photo |
| 1 MB | Email, marketplaces | A full-HD photo in very good quality |
Mistakes to avoid
- Compressing again and again. Every round adds artefacts. Always start from the original.
- Enlarging small pictures. It adds pixels without detail and makes the file bigger.
- Changing the DPI. It doesn’t change the file size at all.
- Renaming the file extension. A PNG renamed to .jpg is still a PNG – and often rejected.
If the form still says no
Check the other rules: many portals also require a specific format, minimum dimensions or an aspect ratio such as 3:4. A file under the limit but in the wrong shape will still be rejected. For the most common limit, the 100 KB compressor has tips for application photos.
Set your limit and compress here
Drop your images here
or
You can also paste an image with Ctrl+V.
Converted on this device. Nothing is uploaded.
Frequently asked questions
What's the difference between KB and KiB?
Strictly, 1 KB is 1,000 bytes and 1 KiB is 1,024 bytes, but many forms say "KB" when they mean 1,024. If your file is under the limit counted in thousands, it passes either way – that's how KeepPixels counts.
Why is my screenshot bigger than my photo?
Screenshots are usually saved as PNG, which is lossless. A PNG of a busy screen can be larger than a JPG photo. Convert it to JPG or compress the PNG with colour reduction.
Can I reduce the size of a PDF here?
No, KeepPixels works with images only. If the form accepts an image, export the PDF page as a JPG first.
Does changing the DPI make the file smaller?
No. DPI is just a note in the file for printing; the number of pixels stays the same, and so does the size. Only fewer pixels or stronger compression shrink the file.