As soon as you move beyond the defaults and attempt to change the “Advanced Settings” it seems to be pretty clear that Rachio was designed for sprinkler irrigation. Period.
Yes, you can specify different kinds of emitters, but the advanced settings seem have little to no relationship to industry standards such as GPH for drip systems. I’ve noticed several people attempting to work around this mismatch (e.g. the spreadsheet from @azdavidr), but it doesn’t seem like they really reflect the reality of drip irrigation vs sprinklers. For example, drip irrigation is a point source of water. The “cup” test doesn’t apply. Also, the total area of a planting area is not really useful because the actual area and depth of water penetration is dependent more on the dispersion characteristics of water in the particular soil type. For example, if I had a single shrub with a 2GPH drip emitter, the actual area and depth of water penetration would not vary whether the shrub was in the middle of a 100 sq ft planter or a 1,000 sq ft planter.
Am I wrong?
If I’m not wrong, it seems to me that Rachio could be tremendously useful to a lot more people, if they provided advanced setting more appropriate to the type of water distribution system chosen, e.g. drip vs spray. All the drip systems I’ve encountered are rated by GPH. I’ve never come across a system rated by inches per hour.
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It’s not that you’re wrong, but more that area and catch cup don’t really apply to drip. I agree that it’d be nice to have what I did in the spreadsheet integrated into the software though, or something similar if it works, for the reason you state that in/hr just doesn’t apply.
Flex works great on drip though, and I’d never to back to what I was doing before. It’s saved me tons of water and hassle, while keeping my vegetation happy in a right desert environment. It’s the initial setup that is hairy due to the translation needed. At least you didn’t have to spend time figuring out the equations that are in the spreadsheet. 
Thank you @azdavidr, for your quick response. I think you have been overly kind to Rachio, since it seems to me that you have essentially “jury-rigged” the Rachio software using a spreadsheet by reverse engineering how it works. I think it’s a travesty that Rachio doesn’t either incorporate settings appropriate for drip systems, or clearly state their product is specifically intended for spray systems. But enough ragging on Rachio. I have a question about your spreadsheet.
I have a large concrete planter area that contains 5 shrubs and some ground cover — all on the same zone. Each plant has its own emitter: 2 GPH for the shrubs and 1 GPH for the ground cover. My plan is to set the irrigation values for the shrubs, and not worry about the ground cover. When I enter the values for the shrubs into your spreadsheet (2 GPH, apply 4 gal, 8" of water), I get a “Nozzle inches per hour” value of 4, and an area of 4. There are 2 things that stand out to me. First, doesn’t the chart showing gal to apply take into account both the width and depth of water dispersion? If so, why also include the inches of water parameter? Second, what does the “Area” value correspond to in real world terms? According to the chart, the 4 gal to apply corresponds to a canopy and root system of 2’ for each plant. That would be π r^2 * 5 or roughly 3.1415 * 1 * 5 = 15.7 sq ft
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@bearish
For both of your questions, the answer is that the ‘area’ parameter in Rachio has no relationship to physical parameters when applied to a drip system, at least that I know of. All the spreadsheet is doing is taking the ‘Inches Applied’ number that Rachio spits out (in your case 8"), and converting it to a PR value that will make sure the zone runs for the right amount of time to give you the total gallons that you want to deliver. In your case you want to apply 4 gal in your case, so given that you have 2 GPH emitters you want the system to run for 2 hours. To confirm this was done properly, once you put in the custom PR number the spreadsheet gives you into Rachio, go to your schedule and look for what it says the watering duration is. It should say 2 hours now, so you’ll deliver 4 gallons with 2GPH emitters.
The only reason to update the ‘Area’ number is if you care about the usage data where the app. lists the number of gallons used. It won’t change anything in terms of irrigation time or schedules, and it doesn’t corresponding to an actual, physical area at all. It’s just giving you a number to put into the app. such that you’ll get accurate estimates of water usage, nothing more.
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Can I get the spreadsheet?
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Sounds like @azdavidr has you heading in the right direction. Yes Rachio take a bit to really dial in a Flex Daily schedule, but one you do, it is amazing how well it works year round.
I do agree that for a consumer based product, it would be nice if the front end UI utilized the common terminology that everyone sees at the box stores when they look at emitters (1gph, 2gph, etc) and do the calculations on the backend. Or at the very least, like @azdavidr mentioned, a linkable chart in the app that would cross things over. But what I will say is the concept of in/hr is exactly how commercial irrigation and ag irrigation figures out watering. So while it may be a bit foregn to consumers, it is a bit more of an irrigation “industry standard”.
It is my understanding that Rachio is primarily a consumer product. If that is true, I believe a truly great UI would allow the user to use values commonplace in the consumer world.
IMHO Rachio does a great job with its UI in so many ways — which makes it all the more frustrating and unbelievable, that they still don’t directly support drip systems (and no, I don’t consider linking to a consumer’s spreadsheet direct support).
I would love to recommend Rachio to friends and neighbors, but I can’t because of the lack of true, direct support for drip. I live in a high desert, and at least in my neighborhood, the majority of people use drip systems almost exclusively.
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