About the Text Size (Letter Height)

Hello. I am quite newbie for overall programming, so I’m unfamiliar with some terms used in building some experiments.

I set the font size (that is written as ‘letter height’ in the builder) as 0.07, but I am not sure what this value means.

Since I am familiar with point units, I wonder if I can change this 0.07 value into point value.

Anyone can help? It would be really helpful.


you can change the unit for the letter height. The default is “unit”, with 1 unit being the height of your screen. This also relates to the position coordinates: (0, 0) is exactly in the middle of the screen. So 0.07 is slighlty less than 1/10 of your screen size. You can change the unit to cm or pixel if you want.


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Answering more as a typography nerd than as a PsychoPy dev here…

“point” units in typography usually go off the Caxton scale I believe, so you can figure out the equivalent in PsychoPy by setting your units to “cm” and using the corresponding values from the left side of this handy ruler which I definitely didn’t spend my real life money buying just because I think it’s cool:

Caxton scale


Thanks for your reply.

I think I understood.

Thanks for your explanation.

I think I have to study more!

You might want to read read through this documentation page: