Image File Size Calculator

Image File Size Calculator – How Big is My Image?

This free online image file size calculator helps you estimate the uncompressed and compressed file size of a raster image based on its pixel dimensions, bit depth, and compression ratio. Perfect for photographers, designers, and anyone working with digital images.

How to Calculate Image File Size

• Enter the width and height of your image in pixels.
• Select the bit depth (bits per pixel) – common values are 24-bit for color photos, 8-bit for grayscale.
• Choose a compression ratio (e.g. 10:1 for JPEG, or None for uncompressed).
• The calculator instantly shows the file size in bits, bytes, KB, MB, and GB for both uncompressed and compressed images.

Image File Size Formula

To get bytes, divide by 8. For kilobytes (KB), divide by 8, then by 1000. For megabytes (MB), divide by 8, then by 1,000,000. For gigabytes (GB), divide by 8, then by 1,000,000,000.

What is Bit Depth?

Bit depth is the number of bits used to represent each pixel. Higher bit depth means more colors and larger file size. For example, 24-bit is standard for true color (RGB), 8-bit for grayscale or 256 colors.

What is Compression Ratio?

Compression ratio is how much the file size is reduced by compression. For example, a 10:1 ratio means the compressed file is 10 times smaller than the uncompressed file. JPEG images often use 10:1 or higher. Lossless formats (like PNG) have lower ratios.

Use Cases

• Estimate storage needs for digital photos and scans.
• Check if your image will fit in an email or upload limit.
• Compare file sizes for different bit depths, resolutions, and compression settings.

References

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