ファイルサイズ計算機

共有リンク

はじめに

File Size Calculator — Estimate uncompressed image file size from resolution, bit depth, and channels. Enter Image Width, Image Height, Bit Depth, Channels (RGB=3, RGBA=4) to get an instant, accurate result.

計算式

Uncompressed file size (bytes) = width (px) × height (px) × (bit depth / 8) × number of channels. This is exact for raw/uncompressed image data only — compressed formats like JPEG produce smaller files.

ステップごとの説明

Enter the Image Width.
Enter the Image Height.
Enter the Bit Depth.
Enter the Channels (RGB=3, RGBA=4).
Click Calculate to see your result instantly.

実例

Example: With Image Width = 6000 px, Image Height = 4000 px, Bit Depth = 8 bits, Channels (RGB=3, RGBA=4) = 3, the File Size Calculator gives Bytes: 72000000, Mb: 72, Gb: 0.072.

よくある質問

Why is my actual JPEG file smaller than this estimate?

This calculator computes the uncompressed size; JPEG and other compressed formats apply lossy or lossless compression that substantially reduces the final file size.

What does "channels" mean?

The number of color components per pixel — 3 for standard RGB, or 4 if an alpha (transparency) channel is included.

What inputs does the File Size Calculator need?

You'll need to provide: Image Width, Image Height, Bit Depth, Channels (RGB=3, RGBA=4). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.

How accurate is the File Size Calculator?

The File Size Calculator applies the formula exactly as calculated — Uncompressed file size (bytes) = width (px) × height (px) × (bit depth / 8) × number of channels. This is exact for raw/uncompressed image data only — compressed formats like JPEG produce smaller files. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.

Is the File Size Calculator free to use?

Yes, the File Size Calculator is completely free, requires no signup, and runs instantly in your browser.