Image File Size
Estimate a photo's file size from resolution, bit depth and compression.
About Image File Size
Multiplying pixel count by bit depth gives the uncompressed data, which compression then shrinks to the stored file size. Estimating file size predicts storage needs, upload times and how many photos fit a memory card.
Formula
Image File Size
Raw bytes = W x H x bit depth / 8; file = raw x compression
- compression
- Fraction of raw size after compression (0.2 = 20%)
Worked example
With the default values below, Image File Size returns Compressed File Size of 6.87. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Pixel widthminimum 1
- 4,000
- Pixel heightminimum 1
- 3,000
- Bit depthminimum 1
- 24
- Compression factorminimum 0.001
- 0.2
Results
- Compressed File Size
- 6.87 MB
- Uncompressed Size
- 34.33 MB
- Compression Ratio
- 20.00%
Step by step
- 1Values used
- 2Image File Size
- 3Compressed File Size= 6.87 MB
- 4Uncompressed Size= 34.33 MB
- 5Compression Ratio= 20.00
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Image File Size calculated?
Raw bytes = W x H x bit depth / 8; file = raw x compression Multiplying pixel count by bit depth gives the uncompressed data, which compression then shrinks to the stored file size.
Why does Image File Size matter?
Estimating file size predicts storage needs, upload times and how many photos fit a memory card.
What values do I need to enter?
This calculator takes 4 inputs: Pixel width, Pixel height, Bit depth, Compression factor. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.