Calculator
What the Image File Size Reducer does
Image File Size Reducer: compress, resize, or convert images in-browser. Everything runs in your browser and the file is never uploaded.
Pick a file and the Image File Size Reducer calculates it right here in the page. Everything runs on your own device, which means no waiting and no copy left on a server.
Getting the dimensions right before upload avoids a lot of downstream cropping. That is usually what brings writers preparing assets for a post here.
The work is done by JavaScript already loaded in your browser, so your input never crosses the network.
Everything needed to verify a result is further down: the fields, the method and one fully worked example.
What do the Image File Size Reducer fields mean?
The Image File Size Reducer uses 4 inputs. None of the boxes start empty. The page loads with a worked set of values you can edit or replace.
| Field | What to enter | Default |
|---|---|---|
| Image file | stays on your device | none |
| Max dimension (px) | choose from Original, 512px, 1024px, 1536px or 2048px | 1024px |
| Quality % | accepts 10 to 100 | 80 |
| Format | choose from WebP, JPEG or PNG | WebP |
How does the Image File Size Reducer 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 calculation.
If something is off you are told which field, not given a generic failure.
What a typical run looks like
You provide: Image file, Max dimension (px), Quality % and Format
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: the output file, and a status line reporting what the tool read and wrote.
A fast machine finishes sooner than a slow one, and the only ceiling on file size is the memory available to the page.
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 Max dimension (px): the options are Original, 512px, 1024px, 1536px or 2048px.
- Type Quality % (10 to 100).
- Pick a value for Format: the options are WebP, JPEG or PNG.
- Press Process Image.
- Read Status in the results panel.
- Use Copy Link if you want the same setup again later, or Print for a paper copy.
What this tool does not do
- Re-encoding a lossy format such as JPEG always loses some detail, even at maximum quality.
- EXIF metadata may be dropped during processing, which is usually desirable but is worth knowing.
- It handles the common case well and the unusual case literally.
- A number that passes validation has been checked for plausibility, not for correctness.
- Performance scales with your own hardware, since no server does the work.
Frequently asked questions
Image file, Max dimension (px), Quality % and Format, nothing else. Each field is pre-filled with a sensible default, so the form is usable immediately, without filling anything in first.
Quality % accepts 10 to 100. The range is enforced before the calculation runs, so a bad entry never reaches the formula.
No. The file is read by your browser and processed inside the page. It is never sent to us, which is also why it keeps working offline once loaded.
Free for any use, personal or commercial.
The formula is shown above precisely so you do not have to take the accuracy on trust.