Work
Estimated file size
At a fixed quality setting, size tracks pixel count. A detailed and noisy frame runs larger than a flat one at the same megapixels, so the figure is a ceiling for planning rather than a promise.
The Formula
estimated megabytes = output megapixels x megabytes per megapixel at the chosen quality
At a fixed quality setting, size tracks pixel count. A detailed and noisy frame runs larger than a flat one at the same megapixels, so the figure is a ceiling for planning rather than a promise.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| MP | Output megapixels | megapixels | Output width times output height, divided by a million. |
| q | Quality tier | MB per MP | Roughly 0.15, 0.30 or 0.60 MB per megapixel. |
| B | Estimated size | MB | The file the export is likely to produce. |
What Each Symbol Means
MPmegapixels
Output megapixels
Output width times output height, divided by a million.
qMB per MP
Quality tier
Roughly 0.15, 0.30 or 0.60 MB per megapixel.
BMB
Estimated size
The file the export is likely to produce.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to resize product images page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Resize Product Images, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.