Image File Size Calculator
Inputs
| Width | 1,920 |
|---|---|
| Height | 1,080 |
| Bit depth | 24 |
Image File Size Calculator
Enter an image resolution and bit depth to calculate the uncompressed file size and total pixel count. Useful for understanding raw camera sensor output, GPU framebuffer allocation, and texture memory.
Inputs
Image Properties
Results
Enter a value to see results.
File Size
Image File Size
Every digital image is a rectangular grid of pixels. Before any compression is applied, each pixel stores a fixed number of bits, and the total bit count determines the raw file size. Understanding this relationship matters for camera sensor design, GPU framebuffer allocation, print resolution planning, and texture memory budgeting in real-time graphics.
The formulas
File size (bytes)=8W×H×b Megapixels=1,000,000W×Hwhere is the width in pixels, is the height in pixels, and is the bit depth (bits per pixel). Dividing by 8 converts bits to bytes.
Worked example. A standard 1080p frame at 24-bit RGB:
F=81920×1080×24=849,766,400=6,220,800 B≈5.9 MiBThat same frame has megapixels.
Bit depth values
| Bit depth | Encoding | Colors / tones per pixel |
|---|---|---|
| 8 bits | Grayscale | 256 gray levels |
| 24 bits | 8-bit RGB | ~16.7 million colors |
| 32 bits | 8-bit RGBA | RGB + 256 alpha levels |
| 48 bits | 16-bit RGB | ~281 trillion colors |
Higher bit depth preserves more detail during post-processing. Editing a 24-bit JPEG repeatedly introduces banding because 8 bits per channel cannot represent the subtle tonal shifts that heavy color grading produces. Professionals shoot 14-bit RAW (stored as 16-bit integers) to maintain headroom.
Why real files are much smaller
This calculator computes the raw, uncompressed size — the size you would need if you stored every pixel without any compression. In practice, image formats reduce this substantially:
- JPEG (lossy): typically 10–20 % of the raw size for photographic content at quality 80.
- PNG (lossless): 40–80 % of the raw size; works best on graphics with flat colors.
- TIFF with LZW: 50–70 % of the raw size, commonly used in professional workflows.
- Camera RAW formats (CR3, ARW, NEF): 30–50 % of the raw size using lossless compression.
Megapixels and print size
At 300 DPI — the standard for high-quality print — each square inch of paper requires pixels. A twelve-megapixel image (four thousand by three thousand pixels) covers roughly thirteen inches horizontally and ten inches vertically at that density, suitable for a large-format print without resampling.
Related calculators
Once you know the raw image size, you can estimate how much space a compressed format will consume using the Compression Ratio Calculator calculator, or check how long a batch of raw files will take to transfer with the Download Time Calculator calculator.
Frequently Asked Questions (FAQ)
What does bit depth mean?
Bit depth is the number of bits assigned to each color channel in a pixel. An 8-bit channel can represent 256 levels of intensity; a 16-bit channel supports 65,536. Standard photographs use 8 bits per channel (24-bit total for RGB), giving over 16 million possible colors. Professional editing workflows often use 16 bits per channel to avoid banding when making large color corrections.
Why is the calculated size larger than my actual image file?
This calculator shows the raw, uncompressed size — every pixel stored as a fixed number of bits with no compression applied. Real image formats reduce this substantially: JPEG typically compresses 24-bit photos to 10–20 % of the raw size, PNG losslessly compresses by 20–50 %, and camera RAW files apply lossless compression that usually cuts the size roughly in half.
What can I do with the megapixel count?
One megapixel is one million pixels. At 300 DPI (the standard for print), each inch of paper needs 300 × 300 = 90,000 pixels, so a 12 MP image can fill a roughly 13 × 10 inch print without resampling. For on-screen display, pixel count maps directly to resolution: a 2 MP image fills a 1920 × 1080 monitor with some cropping room.
What are typical resolutions and their file sizes?
A standard 1080p frame (1920 × 1080) at 24-bit depth is about 6 MB uncompressed. A 4K UHD frame (3840 × 2160) is about 24 MB. A 12 MP smartphone sensor (4000 × 3000) produces roughly 34 MB per raw frame, which is why JPEG compression is so important for everyday photography.