You have your calculations wrong. Q is gallons per minute, and your Moen gave you gallons per hour.
Precipitation rate ( PR ) is a calculation of the flow rate (application rate) over the square footage of the zone. Let’s break down the equation:
PR = (96.25 * Q) / A
96.25 = constant that converts gallons per minute (GPM) to inches per hour. It is derived from 60 minutes per hour divided by 7.48 gallons per cubic foot, times 12 inches per foot.
Q = gallons per minute (GPM)
A = zone square footage (area in ft2)
(96.25*0.011667)/20.6 = .0545"/hr. Seems much closer to what I’d expect from a drip emitter system.
Another option is to check out the excel file that our own @azdavidr created years ago. Makes it REALLY easy!