Calculator
What the Image Format Converter does
Image Format Converter: convert between PNG, JPEG, and WebP locally. Everything runs in your browser and the file is never uploaded.
The Image Format Converter works on a file you choose, without sending it anywhere. Everything runs on your own device, which means no waiting and no copy left on a server.
It is mostly used by people preparing images for the web. A smaller file that still looks right is usually only a few settings away.
Nothing is transmitted: the file is decoded and re-encoded entirely in the browser.
The meaning of each field, the formula in use, and a worked example that starts from the default inputs are all further down.
What do the Image Format Converter fields mean?
The Image Format Converter uses 3 inputs. The defaults are there to be replaced. They exist so the tool is never showing an empty result.
| Field | What to enter | Default |
|---|---|---|
| Image file | stays on your device | none |
| Convert to | choose from PNG, JPEG or WebP | PNG |
| Quality % | accepts 10 to 100 | 90 |
How does the Image Format Converter work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same conversion.
Validation is deliberately strict: silently coercing a bad value is how wrong numbers get trusted.
What a typical run looks like
You provide: Image file, Convert to and Quality %
What happens: the file is read into memory by your browser, processed locally, and offered back as a download. It is never uploaded.
You get back: a processed file plus a short status summary in the tool panel.
The tab does the processing, so speed tracks your hardware and very large files fail on memory rather than on a quota.
Read next: JPEG, PNG, WebP or AVIF: Choosing an Image Format
How to use it
- Choose your file under Image file, or drag it onto the drop area.
- Pick a value for Convert to: the options are PNG, JPEG or WebP.
- Put Quality % (10 to 100).
- Press Convert Format.
- You get Status back.
- Both Copy Link and Print capture the current state, so pick whichever suits how you file things.
What this tool does not do
- EXIF metadata may be dropped during processing, which is usually desirable but is worth knowing.
- Re-encoding a lossy format such as JPEG always loses some detail, even at maximum quality.
- Assumptions built into the method are stated above, but they are still assumptions.
- It validates ranges, not intent. A value can be accepted and still be the wrong one to use.
- Performance scales with your own hardware, since no server does the work.
Frequently asked questions
Only Image file, Convert to and Quality %. A starting value is in place for each, letting you treat it as a what-if tool rather than a data-entry form.
Quality % accepts 10 to 100. Out-of-range entries are refused up front, which is safer than silently clamping them.
It is not uploaded. Everything happens on your device, so no copy of your file exists on any server.
It costs nothing, and there is no limit on repeat use.
It matches what you would get working it out by hand, with fewer opportunities to slip.