Sq Ft vs Sprinkler heads


I suppose that square footage is fine for such things as lawns and gardens. But it seems a bit cart before the horse to me. Specially for something like pots. Wouldn’t it make sense to allow configuration of the number of sprinkler heads if you know that?

For instance I have three zones that are app plants in pots. I know that there are 4 drip heads on one zone, 16 on the second, and 18 on the last. I guess that I would enter those numbers as square foot measurements but it seems strange to supply an area when the software will then use it to estimate the number of heads.


Hi @sbillard, good evening. You ask a good question.

For each zone, the Iro needs to know the precipitation rate at which water is applied to the lawn, pot, etc. At first glance, it does make sense to configure this number around the number of heads, however, each head can have a different type of nozzle/insert which makes the math around output per head tricky.

The software isn’t calculating the number of heads, but rather it’s using the total water being applied by the heads/emitters, etc (as a whole) within the given area (sq ft).

This article does a great job of explaining precipitation rates and ways to calculate it on a zone by zone basis.

Yes, but no – pots and drip zones in general are usually watered with emitters and bubblers. As such, the coverage area is very small due to the point source emission of the water. You’ll need to take the total water output to each pot and the surface area of the soil at the top of the pot to calculate the precip rate.

I hope this helps. Please let us know if you have any other questions we can help with. Happy to help calculate your custom nozzle precip rates if needed.

Best, Emil



I’d even want to go a step beyond what is suggested here and be able to specify every sprinkler head in a zone and precisely what nozzle, etc it has so I can precisely map out a zone. For example, I have a zone in my yard which includes the east side yard + the shrubs/trees in two shrub beds next to my front door. So there are multiple different sprinkler/nozzle combinations at work here (If I recall, there are actually four distinct different sprinkler heads in play making picking a sprinkler for this zone unreasonable, as nothing I pick is going to be accurate for the whole zone). I’d love to be able to draw a little map of the zone, place each different sprinkler head where it actually resides, annotate the exact custom nozzle it is, so that the exact precip rate and water usage is calculated based on exactly what is in a zone. It’d also be useful to be able to specifically annotate in such a map exactly what vegetation is where. I have multiple zones where the vegetation is a mix of grass in some parts, a tree or two, a shrub bed, etc. This would also enable different precip rates for different types of vegetation to be more accurately described.


Ok, I have read the article. I am still missing something, I guess. From the article:

Pr = 96.25 X Total GPM
Total Area

Pr - Precipitation rate in inches per hour.
96.25 - A 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.
Total GPM - The cumulative flow from all sprinklers in the specified area, in gallons per minute (refer to sprinkler charts)
Total Area - The area being irrigated, in square feet.

For the Iro config I can set the nozzle type which implies a cu ft/hour rate. Is this the rate for an individual nozzle or for the combined set of nozzles? If it is for a single nozzle, how does it scale up to the water spread on the whole area?


@cfagyal – I’d love to see this too! Defiantly much easier said than done, but I’ll pitch this idea to the development team and see what they think. I know a few other users have requested the ability to map up their zones via Google Maps, but no one has requested the ability to map out heads yet (at least from my memory).

@sbillard – Great question. The precip rate of the nozzle should be the rate for the combined set of nozzles. If you happen to know the flow rates of the different heads on the zone and the square, I have a custom spreadsheet we could run the numbers through if you need help calculating the precip rate. Sorry for any confusion on this topic.

Best, Emil

 I have a custom spreadsheet we could run the numbers through if you need help calculating the precip rate. Sorry for any confusion on this topic.

I know what the heads are and have an approximate flow rate for each, so, yes, I would like the spreadsheet.


@sbillard, sure thing.

Happy to email you a copy, or feel free to reply with your heads and flow rates and I’ll reply with the precip rates. Let me know your preference.

Best, Emil


That would be ideal Emil, to be able to map zones with Google Maps, and then place pins in spots where sprinkler heads are.

Also useful would be an option in custom nozzles to define the radius that the rotor is covering. My rotors can do anywhere from 40 degrees to 360 degrees, so it’d be cool to be able to define the arc each rotor is covering. Then you could visually see where you are overlapping, which means certain spots are getting more water than others. It’d enable you to customize your nozzle setup in your rotors, and customize the arcs to maximize efficient watering and minimize overlap which is obviously somewhat wasteful.

Sorry for all the ideas…I just have grand visions…this is just such cool technology and i’m quite enjoying it. My Rachio correctly skipped a watering cycle for the third time in a row last night!


I would prefer the spreadsheet. That way as I get better data I can keep things revised.


@sbillard, I’ll send you a copy of the spreadsheet via support. If anyone else wants a copy, feel free to ask.

@cfagyal, that sounds like a great lawn mapping experience! I don’t know of anyone currently doing this, but it’s exactly what professional irrigation designer create. I think the ultimate solution would involve adding some technology to the sprinkler head itself to be able to fine tune it’s adjustment. There’s a few products on the market doing this now (such as Droplet) but they are pretty expensive if one plans on replacing their entire lawn with them.

No need to apologize! Please keep sharing any and all ideas you have. We rely on our users feedback to drive the Iro to the next level.


1+ on the idea of mapping zones & heads using google maps! Or even integrating with an app that does this (not that I’ve found one yet…)


Seams like a installed flow sensor with back end flow reports would alleviate a lot of the disconnects, or just manually reading a meter to get gallons per minute. Maybe Rachio could offer a spreadsheet that automatically pulls in the minutes each zone runs to help with calculations.