Compress Image to a Target Size

To compress an image for an online form, you need two things: the size limit the form states, and a tool that aims for that limit instead of guessing. Dokurapi does exactly that. You set a target (200 KB by default), and it lowers JPEG quality step by step until the file is safely under it, then shows you the quality it ended up using.

What the tool does to your image

The image is decoded by your browser, so any format your browser can open works, including JPG, PNG and WebP. Then:

• If the longest side is larger than 2400 px, the image is scaled down to 2400 px.
• It is encoded as JPEG starting at the starting quality slider value, 84% by default.
• If the file is still too big, quality drops by 10 points per step, for up to 7 steps, and never below 18%. If the file is still too big at the 18% floor, the tool then shrinks the pixel dimensions step by step (never below 640 px on the longest side) and shows the final dimensions in the result.
• It stops at the first result under the safe target, which is your limit times 0.94.

The output is always JPEG. Transparent areas in a PNG become white, which is fine for photos and documents but worth knowing if you are compressing a logo.

Picking a size

Presets cover the common cases, and the custom KB field overrides them when your form uses another number:

KB on this site means 1000 bytes, so 200 KB is 200,000 bytes and the safe target is 188,000 bytes.

Reading the result

After compression you see the original size, the new size and the JPEG quality used. A quality in the 60s to 80s generally looks close to the original on screen. If the tool had to go down to the 20s or 30s, look closely for blocky edges around text and faces. In that case, cropping away empty background before compressing gives the encoder less to store and lets it keep a higher quality.

If the target cannot be reached even at the minimum quality, the tool says so and still offers the smallest version. Try a lower resolution source or a tighter crop.

Privacy and metadata

Your photo is never uploaded; the work happens in the browser tab. Re-encoding also drops EXIF metadata, which removes camera details and GPS location from the file you share. That is a quiet benefit when you send personal photos to forms you do not control. If you need several photos in one document, convert them with photo to PDF instead.