Bitmap Size Calculator
Calculate the uncompressed memory size of a bitmap image from its dimensions and colour depth, useful for understanding raw image data.
Last reviewed by the Radiatus Cloud team
Calculate the uncompressed size of a bitmap image in memory.
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Calculate uncompressed bitmap size
A bitmap stores a colour value for every pixel, so its uncompressed size is simply the number of pixels multiplied by the number of bits used per pixel. This calculator computes that raw size from the width, height and colour depth. A nineteen-twenty by ten-eighty image at twenty-four bits per pixel, the usual depth for full-colour RGB, takes about six megabytes uncompressed, which is why image formats use compression to shrink files dramatically.
The colour depth sets how many bits each pixel uses: twenty-four for RGB, thirty-two with an alpha channel, eight for grayscale, and one for pure black and white.
Why raw size matters
Understanding the uncompressed size explains why formats like JPEG, PNG and WebP exist: without compression, images would be enormous. The raw size is also the amount of memory an image occupies once decoded for display, which matters for performance when many or very large images are loaded. Doubling the dimensions quadruples the pixel count and the raw size.
Compressed file sizes on disk are usually far smaller than this raw figure, varying with the content and format. All calculation happens locally in your browser.
Notes
This Bitmap Size Calculator tool runs entirely in your browser, so nothing you enter is uploaded or stored on a server. The generated output is plain, standards-compliant code that you can copy, paste, edit and reuse freely in your own projects, documents and designs without any attribution or sign-up.
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Frequently Asked Questions
How is bitmap size calculated?
Multiply the width by the height by the bits per pixel, then divide by eight to get bytes. It is the raw, uncompressed size.
What is colour depth?
The number of bits used to store each pixel colour: twenty-four for RGB, thirty-two with transparency, eight for grayscale and one for black and white.
Why is this bigger than my image file?
Image files use compression to shrink the data. This figure is the uncompressed size, which is also the memory used once the image is decoded.
How does size grow with dimensions?
It grows with the pixel count, so doubling both width and height quadruples the number of pixels and the uncompressed size.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Enter the width, height and bits per pixel.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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ImageExtract hidden EXIF data (Camera, GPS, Settings) from images.
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ImageGenerate favicons and app icons at every required size from one source image, with the exact HTML to reference them.
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ImageGenerate placeholder images at any size with custom colours and label text. Produced in your browser as downloadable files, no external hotlinking.