How is RAW file size calculated?

The uncompressed size is pixels times bytes per pixel. A RAW file stores one value per photosite at the chosen bit depth, so size in bytes equals megapixels times one million times bit depth divided by eight. A 24 MP 14-bit sensor is about 42 MB uncompressed.

Why is my real RAW file smaller than the uncompressed figure?

Most cameras apply lossless or visually lossless compression to RAW, typically saving 30 to 60 percent. The tool shows both the theoretical uncompressed size and a realistic compressed estimate using a 0.6 factor, which matches typical lossless-compressed RAW.

How is JPEG size estimated?

JPEG is a lossy compressed format and stores three colour channels of eight bits. The tool starts from the full RGB size (megapixels times three bytes) and divides by a compression ratio you choose, where higher quality means a lower ratio and a larger file.

How many photos fit on my memory card?

Divide the usable card capacity by the per-shot file size. The tool does this automatically once you enter your card size, and accounts for the fact that a 64 GB card holds about 59.6 GiB of usable space due to binary versus decimal gigabytes.

Does bit depth change the JPEG size?

No. JPEG is always eight bits per channel, so RAW bit depth has no effect on the JPEG estimate. Bit depth only affects RAW file size, because RAW preserves the sensor's full tonal range while JPEG discards it.

Image File Size Calculator

Running out of card space mid-shoot is avoidable. This calculator estimates how big your RAW and JPEG files will be from just your sensor resolution and bit depth, then tells you how many frames fit on the card you carry — so you can pack the right capacity before you leave.

How it works

A RAW file records one brightness value per photosite at the camera’s colour bit depth. The uncompressed size is therefore:

bytes = megapixels × 1,000,000 × (bit depth ÷ 8)

For a 24 MP sensor at 14-bit: 24,000,000 × (14 ÷ 8) = 42,000,000 bytes ≈ 40.0 MiB uncompressed.

Real cameras apply lossless or visually lossless compression, which typically shrinks RAW by 30–60%. The tool applies a 0.6 multiplier as a realistic compressed estimate.

A JPEG stores three 8-bit colour channels and then applies lossy DCT compression. We start from the full RGB size and divide by a quality-dependent compression ratio:

jpeg bytes = (megapixels × 1,000,000 × 3) ÷ compression ratio

A ratio of 10 is a good high-quality JPEG; a ratio of 4 is near-maximum quality; a ratio of 20 is a smaller web-grade file.

Shots per card

Memory cards are sold in decimal gigabytes (1 GB = 1,000,000,000 bytes) but filesystems report binary gibibytes. The tool converts your card size to bytes, applies a small formatting overhead, and divides by the per-shot size to give a realistic shot count.

Notes and tips

Bit depth only affects RAW. JPEG is always 8-bit per channel, so changing bit depth never changes the JPEG estimate.
Pixel dimensions beat the megapixel label. Marketing megapixels are rounded; if you know the exact width and height, enter them for an exact figure.
Burst shooting fills cards fast. A 45 MP camera at 14-bit RAW produces roughly 50–80 MB per frame after compression — a 20 fps burst can write over a gigabyte per second.

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