Many of you may be aware that no matter what the zoom level SumatraPDF Measure tool will report the page dimensions accurately.
However on occasion, it is useful to know that 100% scale in SumatraPDF is as close as is possible to real size on screen for quick diagonal measurements.
And we can alter per user settings to ensure the physical scale on screen is reasonable. You can edit and save the values as you alter them, and press R in SumatraPDF to quickly see the effect, so here I need a CustomScreenDPI setting of 101 to take quick measurements with a scale rule.
However, I also know that will not work for a screen grab since pasting into MS paint shows it as 5% oversized
And for that task I need to reset to the Microsoft 100% Screen default value of 96
These values are for my system @ 100% screen scaling it will differ for each machine so I keep a note on each machine If I need to change it quickly.
If you want a fixed inch grid to load into SumatraPDF here it is Dimensions should be 1057 x 769 pixels