Erik--this might be a dumb question (decent chance of that) but what causes the inflation when you average uphill and downhill putts?

I'll confess to being a complete simpleton here as I had just presumed that averaging the uphill and downhill speed would get you a accurate number.

Kalen answered it, I think. The steeper the slope or the higher the stimp, the farther the difference between uphill and downhill putts will be.

Think about it this way. If the stimp is 1, and the slope is 1%, the

*by far* dominant factor is the friction of the green, not the pull of gravity. Conversely, if you had a 10% slope on a stimp 10 green, the ball wouldn't even stop downhill (it'd actually accelerate), so you'd be averaging infinite distance and maybe 7' or something. Gravity is the dominant factor, or a much bigger factor, than the first example.

Averaging almost always leads to a higher number, and since almost no greens have 11' or more of actually flat surface… stimp ratings tend to be high even if you try to get them accurate.

PGA Tour greens are 10.5-11, typically. The Masters (ANGC) can creep toward 12. It's been just over 12 a few times.

A quick way to find an accurate stimp rating is to find the point at which the ball rolls away (i.e. you set a ball down and, on its own, it starts rolling).

`70/stimp = % slope for roll-away`. So at stimp 10, a ball will roll away at 7% slope.