: Given one exact measurement, how can I use it to measure the rest? I'm asking how to use a given measurement to create a custom scale that I can use to accurately measure the rest. I have

@Michele215

You can do this with Photoshop using the Ruler Tool and a Custom Measurement Scale.

Using your provided image as an example, do the following:


Activate the Ruler Tool (you may have to click and hold the eyedropper tool)
Check the Use Measurement Scale tickbox on the top toolbar
Measure the width of the provided scale (541 pixels)
Go to Analysis → Set Measurement Scale → Custom...
Enter the known values and hit OK




The ruler measurements will now use your custom scale. For instance, it looks like the tires are 752mm tall



To revert back to pixel measurements, you can untick "Use Measurement Scale"

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