Image File Size
Calculate uncompressed raster image file size from width, height, and bit depth. Free image file size calculator for photographers and designers with charts.
About This Calculator
The Image File Size Calculator estimates the uncompressed file size of any raster image based on its pixel dimensions and bit depth. Photographers, graphic designers, web developers, and digital artists use it to plan storage requirements, compare format efficiency, and understand how resolution and color depth impact file sizes before exporting or uploading images.
The calculation follows the standard formula for uncompressed raster data: multiply the image width by height to get the total pixel count, then multiply by the bit depth (bits per pixel) to get total bits. Divide by 8 to convert to bytes, then by 1024 sequentially to get kilobytes (KB), megabytes (MB), or gigabytes (GB). This gives the raw data size before any compression is applied — actual file sizes in JPEG, PNG, WebP, or HEIF formats will be smaller due to compression algorithms.
Regional Notes
Global: This calculator is unit-agnostic and works for any region. The pixel dimensions (width × height) and bit depth are universal measurement units. File size is displayed in KB, MB, and GB using the binary convention (1 KB = 1024 bytes), which matches how operating systems like Windows, macOS, and Linux report file sizes.
Frequently Asked Questions
How do I calculate image file size?
Multiply the image width by height to get the pixel count, then multiply by the bit depth (bits per pixel). Divide by 8 to get bytes, then by 1024 to get kilobytes (KB) or 1,048,576 for megabytes (MB). For a 1920×1080 image at 24-bit depth: pixel count = 2,073,600, total bits = 49,766,400, file size ≈ 5.93 MB.
What is bit depth in image files?
Bit depth determines how many colors each pixel can display. A 1-bit image shows 2 colors (black and white), 8-bit shows 256 colors, 24-bit (true color) shows 16.7 million colors, and 48-bit deep color shows 281 trillion colors. Higher bit depth means larger file sizes but better color accuracy and smoother gradients.
Does this calculator work for compressed images like JPEG or PNG?
This calculator estimates the size of uncompressed raster image data. Compressed formats like JPEG, PNG, or WebP use lossy or lossless compression algorithms that reduce file size significantly. Actual compressed sizes depend on image content, compression quality settings, and format-specific optimizations. The result gives the upper bound before compression.
What image file formats are raster-based?
Common raster image formats include BMP, TIFF (uncompressed), JPEG, PNG, GIF, WebP, and HEIF. Vector formats like SVG, AI, and EPS use mathematical equations instead of pixel grids and have file sizes that depend on complexity rather than dimensions and bit depth.
How many megapixels is a 1920×1080 image?
A 1920×1080 image has 2,073,600 pixels, which is approximately 2.07 megapixels (MP). Megapixels are calculated by multiplying width by height in pixels and dividing by one million.
What is the difference between raster and vector images?
Raster images store color data for each pixel in a grid, making them resolution-dependent — they lose quality when enlarged. Vector images store shapes and curves as mathematical formulas, so they scale infinitely without quality loss. Raster file size depends on dimensions × bit depth, while vector size depends on object complexity.
How does resolution affect image file size?
File size grows linearly with pixel count. Doubling both width and height quadruples the pixel count and file size. For example, a 640×480 image at 24-bit is 921.6 KB, while a 1920×1080 image at the same bit depth is about 5.93 MB — roughly 6.4× larger for 6.75× more pixels.