McLaren synthetic chanter reed strength guide

You’ve probably heard by now about Malcolm McLaren’s synthetic bagpipe chanter reeds. He gives a rough guide as to the strength ratings he uses (13-20) by giving the equivalent values in inches of water for 3 of his reed strengths (13 = 18 in. H2O, 17 = 28 in. H2O, 20 = 35 in. H2O). It is immediately obvious that the scale is roughly linear. So this is a trivial post, I’m just going to fill in the gaps for ya.

McLaren in. H2O McLaren in. H2O
12.97 18 13 18.07
13.38 19 14 20.5
13.79 20 15 22.93
14.2 21 16 25.36
14.61 22 17 27.79
15.02 23 18 30.23
15.43 24 19 32.66
15.84 25 20 35.09
16.26 26
16.67 27
17.08 28
17.49 29
17.9 30
18.31 31
18.72 32
19.13 33
19.54 34
19.95 35

The equations are:
McLaren = 0.41095890411 * (in. H2O) + 5.570776255708
in. H2O = 2.431432432432 * (McLaren) – 13.540540540541