Images & files
Compare image exports by their actual file size.
Choose an original image and its finished export to measure the exact byte change—without uploading either file. Optional page-payload projections are labeled as estimates because caching, responsive delivery, and CDN behavior change what a visitor actually transfers.
- Two real files
- Runs entirely in your browser
- Exact bytes + labeled estimates
Two-file comparison
Choose the files to measure.
Browser-only measurement. Both files stay on this device. No image, filename, or result is sent or persistently stored.
Measured result
Compare the actual file bytes.
Select the original and finished export. The tool will report real bytes for those files—not predict what an encoder might create.
Choose the original image and its finished export to begin.
What the result means
Measure the export. Keep the projection honest.
| Result | How it is calculated | What it can tell you |
|---|---|---|
| Actual file bytes | Reads each selected file's byte length locally | The exact stored size of those two files |
| Signed byte change | Finished export minus original | Whether this export is smaller, identical, or larger |
| Bits per pixel | Export bytes × 8 ÷ exported pixel count | A descriptive density—not a visual-quality score |
| Nominal payload estimate | Export bytes × image count × page views | A simple planning ceiling before delivery behavior |
Image content, dimensions, quality, metadata, and encoder choices all affect output size. The tool compares two files that already exist instead of inventing a precision formula. File-size labels use binary units: 1 KB equals 1,024 bytes.
Browser caches, responsive image choices, compression in transit, CDN transforms, request headers, and repeat visits can all change the transferred byte total. Use the projection to compare scenarios—not as an analytics or hosting-bill forecast.
The calculator accepts static PNG, JPEG/JFIF, and WebP files. It rejects SVG and animation, verifies file signatures and header dimensions, and does not decode or display the image. Need to make an export first? Use the Image Compressor & Resizer or Image Format Converter.
Primary sources
The boundary between stored and transferred bytes.
Reviewed August 24, 2026. The exact comparison uses the browser File API; the delivery caveats follow HTTP caching, Resource Timing, and responsive-image behavior.