Image File Size Calculator
Calculate the uncompressed size of an image from width, height and bit depth, in bytes, KB/MB and KiB/MiB, plus the exact size of a BMP file.
This is the raw pixel data, as held in memory or in an uncompressed BMP/TIFF. PNG, JPEG, WebP and HEIC files are compressed, so they are usually much smaller, and how much depends on the picture.
| Bits per pixel | Bytes | MB | MiB |
|---|---|---|---|
| 1 | 259,200 | 0.259 | 0.247 |
| 8 | 2,073,600 | 2.074 | 1.978 |
| 16 | 4,147,200 | 4.147 | 3.955 |
| 24 | 6,220,800 | 6.221 | 5.933 |
| 32 | 8,294,400 | 8.294 | 7.91 |
| 48 | 12,441,600 | 12.442 | 11.865 |
| 64 | 16,588,800 | 16.589 | 15.82 |
Every pixel of an image needs a certain number of bits, so the raw size of a picture follows directly from its width, height and colour depth. That raw size is what an image takes up in memory, in a graphics card or in an uncompressed BMP or TIFF file — and the starting point for judging how well PNG or JPEG compress it. Enter the dimensions and bit depth to get the size in bytes, decimal and binary units, and the exact BMP file size.
How to use this tool
- Enter the width and height in pixels.
- Pick the colour depth: 24 bits for normal photos, 32 with transparency, 8 for greyscale or 256-colour images.
- For animations or batches, enter the number of frames or images.
- Read the size in bytes, KB/MB and KiB/MiB; the table compares other depths.
Formula
size in bytes = ⌈width × bits per pixel ÷ 8⌉ × height × images
Each row is rounded up to whole bytes, which only matters below 8 bits per pixel. Decimal units use 1 KB = 1,000 bytes and 1 MB = 1,000,000 bytes, as storage makers and macOS do; binary units use 1 KiB = 1,024 and 1 MiB = 1,048,576 bytes, as Windows Explorer does while labelling them "KB" and "MB". A BMP file pads every row to a multiple of 4 bytes and adds a 54-byte header, plus a palette of 4 bytes per colour at 8 bits or less.
Example
A Full HD screenshot of 1920 × 1080 px in 24-bit colour holds 1920 × 1080 × 24 ÷ 8 = 6,220,800 bytes: 6.22 MB, or 5.93 MiB. Saved as a BMP it is 6,220,854 bytes; as a PNG it is typically far smaller, because PNG compresses repeated colours.
Frequently asked questions
Why is my JPEG so much smaller?
JPEG, PNG, WebP and HEIC compress the pixel data. A Full HD photo of 6.2 MB raw is usually well under 1 MB as a JPEG; how much smaller depends on the quality setting and the detail in the picture.
Should I use MB or MiB?
Both are correct but different: 1 MiB is 4.9% larger than 1 MB. Upload limits on websites are usually in decimal MB; Windows shows binary values but calls them MB.
How much memory does a photo need in an app?
Browsers and apps usually decode images to 32 bits per pixel, so a 12-megapixel photo takes about 48 MB of memory, whatever its file size.
Last updated:
Page address with these inputs: https://kakao.mobile/tools/image-file-size-calculator/
Cite or embed this tool
kakaoCalc. (2026, November 8). Image File Size Calculator. https://kakao.mobile/tools/image-file-size-calculator/
“Image File Size Calculator.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/image-file-size-calculator/.
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