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Image data, before saving

Image file size calculator

Find the storage needed for the pixels themselves before choosing a file format. Set the image dimensions, color channels and bits per channel; the result deliberately excludes compression and file overhead.

Enter your values

Result

Results are based only on the inputs and assumptions shown here. Nothing you enter is sent or saved.

Formula: bytes = width × height × channels × bits per channel ÷ 8

Worked example

A 4,000 × 3,000 RGB image at 8 bits/channel has 36,000,000 pixel-data bytes: 36 MB or about 34.33 MiB.

What this number includes

This is the raw, tightly packed pixel array for a single flattened image. RGB at 8 bits per channel has 24 bits, or three bytes, per pixel. A fourth alpha channel adds another byte at this depth. Adobe explains why increasing bit depth increases stored color information and image size.

Why a saved file differs

JPEG compression, PNG filters, TIFF options, headers, metadata, color profiles, layers and row padding can all change the saved size. A compressed file cannot be predicted from dimensions alone because its content and encoder settings matter. Treat the answer as a pixel-data estimate, not a download-size promise.

Choose the right dimensions

Use actual pixel dimensions, not print inches or a DPI tag. For a planned print, use the main pixels-to-inches calculator first; for a planned scan, use the scan-resolution calculator. The arithmetic on this page stays in your browser.

Explore the related calculation

For a different starting point, try the scan resolution planner or return to the main calculator. Browse the complete tool directory for this site.

Reference and corrections

The definitions and assumptions above follow these sources; the examples and calculator arithmetic are original to this page.

Found a problem? Email contact@pixelstoinches.org.