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File Size Estimator
Estimate how large a compressed image will be from its pixel dimensions, quality setting and content type.
Estimate an image file size
Estimated size: —
Megapixels: — · Uncompressed: —
How to use the File Size Estimator
- Enter the pixel width and height of the image you plan to export.
- Choose the output format, the content type and the quality setting.
- Read the estimated size and compare qualities and formats in the table.
Features
- Bits-per-pixel estimate for JPEG, WebP and PNG
- Quality, content type and dimensions all affect the model
- Table across five qualities and three formats
- Megapixel and uncompressed size figures
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Frequently Asked Questions
Common questions about the free online file size estimator.
The tool multiplies the pixel count by a bits-per-pixel figure for the chosen format, quality
and content type, then adds a small header overhead.
It is usually within about 30 percent for photos. Very noisy or very flat images can differ
more, so treat the number as a guide.
Smooth graphics and screenshots compress far better than detailed photographs, so the model
uses a lower bits-per-pixel value for them.
Quality 80 to 90 keeps good detail at a reasonable size. Below 60 the file shrinks fast but
blocking artefacts start to show.
Usually yes. At the same quality WebP is often 25 to 35 percent smaller, which the estimate
table shows side by side.
The estimator also shows the raw size, which is three bytes per pixel or roughly 36 MB for a
12 megapixel photo.
PNG is a lossless format, so there is no quality setting. Its size depends on the content and
the number of distinct colours.
No. The estimate is simple arithmetic performed in your browser, so nothing you type is sent
to a server.
Yes. The estimator is fully responsive and works on phones, tablets and desktop browsers.
Last updated: October 10, 2026