Image File Size Calculator
Calculate the uncompressed memory and raw bitmap size of an image using its pixel dimensions and color depth.
Calculate Image Size
Enter your image dimensions and select the color depth to calculate the raw uncompressed size.
Uncompressed Raw Size
Estimated memory required to store every pixel without compression.
Width × Height × Color Depth ÷ 8 = Bytes
How Image File Size Is Calculated
An uncompressed image stores information for every individual pixel. The total amount of raw memory required depends on the image width, image height, and number of bits used to represent each pixel.
This calculator estimates the raw uncompressed pixel data. It does not estimate the final file size of compressed formats such as JPEG, PNG, or WebP.
8-bit
An 8-bit grayscale image can represent up to 256 possible intensity levels per pixel.
24-bit
A 24-bit RGB image typically uses 8 bits each for red, green, and blue channels.
32-bit
A 32-bit image commonly uses 24 bits for RGB color plus an additional 8-bit alpha channel.
Image File Size Formula
The raw image size can be calculated by multiplying the image width by its height and then multiplying the result by the color depth in bits.
Width × Height × Bits Per Pixel ÷ 8
= Bytes
Example: 3840 × 2160 Image
A 3840 × 2160 image contains 8,294,400 pixels. At 24 bits per pixel, each pixel requires 3 bytes.
Therefore:
3840 × 2160 × 24 ÷ 8
= 24,883,200 bytes
24,883,200 bytes
≈ 23.73 MiB
Uncompressed vs Compressed Image Files
This calculator estimates the raw memory required when image pixels are stored without compression. The actual file size can be considerably smaller when a compression format is used.
JPEG, PNG, WebP, and other image formats use different compression methods. Their final file sizes depend on factors such as image content, compression settings, metadata, color information, and the selected format.
For example, a 3840 × 2160 image at 24-bit color requires approximately 23.73 MiB of raw pixel memory even if its compressed JPEG or WebP file occupies substantially less storage space.
Common Image Resolutions
The calculator includes several common display and video resolutions for quick calculations.
- Full HD: 1920 × 1080 pixels
- 2K / QHD: 2560 × 1440 pixels
- 4K / UHD: 3840 × 2160 pixels
- 8K / UHD: 7680 × 4320 pixels
Frequently Asked Questions
What does an image file size calculator calculate?
This calculator estimates the raw uncompressed memory required to store an image based on its pixel dimensions and color depth.
Does this calculate JPEG file size?
No. JPEG files are compressed, so their final file size depends on image content and compression settings. This calculator estimates uncompressed pixel memory.
What is 24-bit color?
24-bit color commonly uses 8 bits for each of the red, green, and blue channels, giving 24 bits or 3 bytes per pixel.
What is 32-bit color?
32-bit images commonly contain 24 bits of RGB color information plus 8 bits for an alpha transparency channel.
Why are the results shown in KiB and MiB?
The calculator uses binary units based on 1024 bytes. Therefore, the technically correct units are KiB, MiB, and GiB rather than decimal KB, MB, and GB.