Image File Size Estimator

Uncompressed Image Size

The raw, uncompressed size of an image is calculated as:

Size (bytes) = Width × Height × Channels × (Bit Depth ÷ 8)

For example, a 6000×4000 pixel image at 14-bit RGB has 24 million pixels, each storing 3 channels at 14 bits = 5.25 bytes per pixel, totaling about 126 MB uncompressed.

Compression Ratios

Different formats apply different levels of compression to reduce file size:

• RAW: Camera sensor data with light lossless compression. Typically 50–70% of the theoretical uncompressed sensor data size, depending on the camera manufacturer's compression algorithm.
• TIFF (uncompressed): Stores the full pixel data without compression, 100% of the calculated uncompressed size.
• TIFF (LZW): Lossless compression reduces size to roughly 50–70% of uncompressed, depending on image content.
• PNG: Lossless DEFLATE compression typically achieves 30–60% of uncompressed size for photographic content.
• BMP: No compression, 100% of uncompressed size plus a small header.
• JPEG: Lossy DCT-based compression. Quality 100% yields roughly 1:4 ratio, quality 80% roughly 1:10, quality 60% roughly 1:18, quality 20% roughly 1:40.
• WebP: Modern format with better compression than JPEG. Lossy WebP at equivalent quality is roughly 25–35% smaller than JPEG.

Bit Depth Explained

Bit depth determines how many distinct values each color channel can represent:

• 8-bit: 256 levels per channel (16.7 million colors for RGB). Standard for displays and JPEG.
• 10-bit: 1,024 levels. Used in video and some displays.
• 12-bit: 4,096 levels. Common in entry-level RAW files.
• 14-bit: 16,384 levels. Standard for professional camera RAW files.
• 16-bit: 65,536 levels. Used in TIFF for high-quality editing.
• 32-bit float: HDR imaging, scientific data, and compositing.

Important Notes

• These are estimates. Actual file sizes vary based on image content — images with more detail or noise compress less efficiently.
• RAW file sizes depend heavily on the camera manufacturer's proprietary format and compression.
• JPEG compression efficiency varies with image complexity — smooth gradients compress better than detailed textures.
• Metadata (EXIF, ICC profiles, XMP) adds a small overhead not included in these estimates.

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