Radius question

[nuke]

If anyone wants to actually measure, a set of under-string radius gauges is pretty cheap, under $10 from the usual online sources. 

 

Or for $0, get a string, a pencil, an exacto blade, a ruler and some poster board, index card or some other sturdy bit of paper. 

Tie the pencil to the string and a fixed point like a thumbtack at 12 inches, draw an arc on the index card. Repeat for 10, 11, 13. Trim the arc off with the exacto just wider than the width of your fingerboard. Then measure what you got.  (how we did it before pre-made guitar tools became commonplace).