File Size Calculator

TL;DR: To calculate the uncompressed file size, multiply the pixel dimensions (width × height) by the bit depth (bits per pixel), then divide by 8 to convert bits to bytes, and finally divide by 1,048,576 to convert bytes to megabytes — for a 1920×1080 image at 24-bit color, the calculation is (1920 × 1080 × 24) ÷ 8 ÷ 1,048,576 = 5.93 MB.

What Is the File Size Calculator?

This File Size Calculator determines the exact storage space required for an uncompressed digital image or video frame based purely on its raw pixel data. Unlike compressed formats like JPEG, PNG, or MP4, uncompressed files store every single pixel’s color information without any lossy or lossless compression algorithms. This tool is essential for digital photographers, video editors, graphic designers, and system administrators who need to estimate storage requirements for RAW photography, bitmap sequences, or uncompressed video workflows.

For example, a professional photographer shooting in RAW format knows that a 24-megapixel camera with a 14-bit sensor produces substantially larger files than a 12-megapixel camera with an 8-bit sensor. Similarly, a video editor working with uncompressed 4K footage must calculate frame sizes to predict how much SSD or RAID storage will be consumed over a professional editing session. This calculator eliminates guesswork by delivering a precise byte count based on three fundamental inputs: dimensions and color depth.

The calculation is deterministic — there is no randomness or variability. If you know the exact pixels and bit depth, you know the file size with 100% accuracy before the file even exists. This makes the tool invaluable for project budgeting, server capacity planning, and choosing the right compression settings when storage space is limited.

How to Use the Calculator

Using this calculator is straightforward — enter three values, and the result appears instantly. Follow these steps for accurate results:

1. Enter the image width in pixels: This is the horizontal dimension of the image. For a standard 1920×1080 display, enter 1920. For a 4K video frame, enter 3840. Ensure you are entering pixel counts, not print dimensions in inches or centimeters.
2. Enter the image height in pixels: This is the vertical dimension. For the same 1920×1080 example, enter 1080. For square images, this equals the width; for portrait orientation, this is the larger number.
3. Select or enter the bit depth: This is the number of bits used to represent color per pixel. Common values are 8 (256 colors per channel, standard for JPEG), 16 (65,536 colors per channel, high-quality TIFF), 24 (true color, 16.7 million colors — 8 bits per RGB channel), and 32 (24-bit color plus 8-bit alpha transparency channel). If you are unsure, 24 is the most common default for standard images.
4. Click or press Calculate: The calculator will instantly output the uncompressed file size in bytes, kilobytes (KB), megabytes (MB), and gigabytes (GB) so you can use the most convenient unit for your storage context.

That’s it — no hidden settings, no additional parameters. The calculator assumes no compression, no metadata overhead, and no file-system cluster slack. You are getting the pure raw pixel data size.

Formula and Calculation Method

The underlying formula is simple multiplication followed by unit conversion. The total number of bits in the image equals the total number of pixels multiplied by the number of bits per pixel. Since there are 8 bits in 1 byte, you divide by 8 to get bytes. To convert to kilobytes, divide by 1,024; to megabytes, divide by 1,048,576 (1,024 × 1,024).

The formula is:

File Size (bytes) = (Width × Height × Bit Depth) ÷ 8

Then for MB: File Size (MB) = (Width × Height × Bit Depth) ÷ 8 ÷ 1,048,576

Let’s walk through the exact scenario from the calculator description: a 1920×1080 image with 24-bit color depth.

1. Total pixels = 1920 × 1080 = 2,073,600 pixels
2. Total bits = 2,073,600 × 24 = 49,766,400 bits
3. Convert to bytes: 49,766,400 ÷ 8 = 6,220,800 bytes
4. Convert to megabytes: 6,220,800 ÷ 1,048,576 = 5.93 MB

So a full HD 1080p image at true color (24-bit) occupies 5.93 megabytes of uncompressed storage. If you store 100 such images, you need approximately 593 MB of free space. If this is a video at 30 frames per second, one second of footage requires 30 × 5.93 MB = 177.9 MB, meaning a 10-minute clip would consume over 100 GB.

Practical Examples

To show the formula in action across different real-world use cases, here are three scenarios with varying inputs and their implications.

Notice how bit depth dramatically affects size. In the medium-format example, dropping from 16-bit to 8-bit would halve the file to roughly 49 MB, but would also degrade the color gradient quality. In the 4K video example, opting for 12-bit RAW video instead of 24-bit standard color would reduce storage needs by half while still maintaining professional color grading flexibility.

Tips for Accurate Results

Common mistakes can lead to wildly incorrect file size estimates. Here are the most frequent pitfalls and how to avoid them:

• Never forget to divide by 8: The most frequent error is leaving the result in bits rather than bytes. A 1920×1080×24 image computes to 49,766,400 bits — that number looks like a plausible file size, but it is wrong. The actual file is 6,220,800 bytes (about 5.93 MB), not 49.76 MB. Always divide bits by 8.
• Do not confuse bits with bytes in naming: Internet speeds are measured in bits per second (Mbps), but file sizes are in bytes (MB). A 5.93 MB image at 25 Mbps connection takes 1.9 seconds to transfer, but a 49.76 Mb (megabit) misconception would imply a transfer time of 2 seconds — the difference matters when calculating total workflow time.
• Compression is not accounted for: This calculator gives the uncompressed size. A JPEG of the same image might be only 500 KB to 2 MB. If you are estimating final file sizes after saving in JPEG or PNG, this tool will overestimate by 3–10×. Use it for RAW, BMP, TIFF (uncompressed), or video codecs like FFV1 or uncompressed AVI.
• Bit depth selection must match your actual pixel format: A 24-bit image has 8 bits per channel (Red, Green, Blue). A 32-bit image adds an 8-bit alpha channel (transparency). If you export a PNG with alpha, but compute at 24-bit, you will underestimate by 33%. Check your software’s settings to confirm the exact bits per pixel.
• Check dimension units: Ensure your width and height are in pixels, not DPI-adjusted print sizes. A 10×8 inch photo at 300 DPI is 3000×2400 pixels, but if you enter 10 and 8 with a 24-bit depth, the calculator gives you a completely invalid result.
• Consider file system overhead: The calculator output is the logical file size. On a disk, the file will take up additional space due to cluster allocation (typically 4 KB per file minimum). For this image, the overhead is negligible (4 KB), but for thousands of tiny 1 KB files, overhead can consume 75% of allocated space.

Frequently Asked Questions

Why does my JPEG file show a different size than this calculator?

The File Size Calculator computes the size of a completely uncompressed image — that is, the raw bitmap stored in memory or as a BMP/TIFF-file. JPEG uses lossy compression that removes visual data the human eye is unlikely to notice, often reducing file size by 90–95%. For a 1920×1080 24-bit image that computes to 5.93 MB uncompressed, a high-quality JPEG (quality setting 90) might only be 800 KB to 1.5 MB, while a low-quality JPEG might compress to 300 KB. PNG uses lossless compression, typically yielding 2–4 MB for the same image. If your JPEG is larger than the uncompressed estimate, check that you entered bit depth correctly — some software defaults to 32-bit (adding alpha), and avoid saving screenshots with complex gradients as high-quality JPEGs where compression is less effective.

How do I calculate video storage requirements using this tool?

To find how much storage an uncompressed video file will consume, first calculate the file size of a single frame using the calculator, then multiply by the frame rate (frames per second) and the duration in seconds. For example, a 1080p (1920×1080), 24-bit color video result is 5.93 MB per frame. At 30 fps, one second of video is 5.93 × 30 = 177.9 MB. A 10-minute clip (600 seconds) therefore requires 177.9 × 600 = 106,740 MB, or about 104.2 GB. For 4K at 60 fps, each frame is 23.73 MB, so one second is 1,423.8 MB, and a 2-hour movie would require over 10 TB — which is why uncompressed video is rarely used outside of high-end editing suites. Always calculate for the exact frame rate; 24 fps (cinematic) vs 30 fps vs 60 fps makes a huge difference in total storage.

What is the difference between 24-bit, 32-bit, and 16-bit — when should I use each?

Bit depth directly determines file size and color accuracy. 24-bit is “true color” — 8 bits each for Red, Green, and Blue, giving 16.7 million color combinations. It is the standard for web graphics, digital photography, and most displays. 32-bit adds an 8-bit alpha channel for transparency, making the file 33% larger (as seen in the formula where bit depth is 32 vs 24). Use 32-bit when you need PNG files with transparency for logos, icons, or image composites. 16-bit (often called high color) uses 5–6 bits per channel, producing only 65,536 colors — you should only use it for very old game assets or cases where the final file will be viewed on a 16-bit display. For professional photography editing, you might work with 48-bit (16 bits per channel) in tools like Photoshop to avoid banding in gradients; this doubles the file size compared to 24-bit. The calculator handles any bit depth you enter, so just ensure you match the number to your software’s actual pixel format setting.