Sprinkler Head Spacing and Head-to-Head Coverage Explained
Sprinklers spray a doughnut-shaped pattern that is weakest at its edges, so heads must overlap all the way to each other. Space heads at about their radius, choose a triangular or square grid, and derate for wind, and you'll get the even coverage that eliminates dry spots.
Why Sprinklers Need to Overlap
Every sprinkler applies the most water close to the head and progressively less toward the outer edge of its throw. Plotted out, the coverage looks like a doughnut: soaked in the middle band, thin at the rim, and dry at the very edge. If you space heads so their patterns just barely touch, the thin outer rings meet and you get chronic dry spots, rings, and stripes exactly where the two weak edges overlap.
The fix is head-to-head coverage: each head is placed so its spray reaches all the way to the next head. Every point on the lawn is then watered by at least two heads, the strong inner water from one filling in the weak edge of another. This overlap is not optional or excessive; it is the designed, intended way sprinklers achieve uniform coverage.
The Core Spacing Rule
Head-to-head coverage means the distance between heads should equal the radius of their throw, which is the same as spacing them at roughly 50 percent of their diameter. A rotor that throws 30 feet (a 60-foot diameter) should have its neighbors about 30 feet away. A spray head throwing 12 feet should have neighbors about 12 feet away.
This is a starting point, not a ceiling. Real yards have wind, pressure variation, and pattern imperfections, so most designers treat "space at the radius" as the maximum and pull heads slightly closer when conditions call for it.
Tip: When in doubt, space heads a little tighter rather than wider. Overlapping too much costs a few extra heads; overlapping too little bakes permanent dry spots into your lawn.
Triangular vs. Square Spacing
There are two common layout grids, and the choice affects how many heads you need and how even the coverage is.
Square (grid) spacing places heads in straight rows and columns, each head at the corner of a square. It is simple to lay out and works well along straight edges and rectangular lawns.
Triangular (staggered) spacing offsets every other row so heads form triangles instead of squares. This packs the coverage circles more efficiently, letting each head sit slightly farther apart while still overlapping. Triangular spacing covers roughly 15 percent more area per head than square spacing, so it uses fewer heads for the same lawn and generally gives more uniform coverage in open areas.
Use triangular layouts in large open turf where you have room to stagger. Fall back to square spacing along narrow strips, borders, and rectangular areas where a staggered grid won't fit cleanly. Rotors and rotary nozzles are covered by type in spray, rotor, and drip heads.
Derating for Wind
Manufacturer radius figures assume calm conditions. Wind pushes water off target and shrinks effective coverage, so you must reduce your spacing in windy sites. A common approach is to derate spacing by 10 to 30 percent based on typical wind:
- Light wind (under ~4 mph): derate about 10 percent
- Moderate wind (~4–8 mph): derate about 20 percent
- Strong or frequent wind (over ~8 mph): derate about 30 percent
To derate, multiply the radius-based spacing by the remaining percentage. A 30-foot rotor spacing in a moderately windy yard becomes about 24 feet (30 × 0.80). Large-droplet heads like rotors and rotary nozzles resist wind better than fine spray mist, so fixed sprays usually need the more aggressive derating.
Matched Precipitation on the Zone
Spacing and coverage only stay even if every head on a zone applies water at the same rate. This is matched precipitation. Nozzles are made so a quarter-circle head puts out roughly a quarter the flow of a full-circle head covering the same radius, so a corner and a middle head deposit the same depth per hour. If you mix mismatched nozzles, or mix head types, some areas over-water while others stay dry no matter how perfectly you spaced them. Keep one head type and matched nozzles per zone, and size the zone to your flow using water pressure and GPM.
Worked Spacing Examples
The table below shows maximum head-to-head spacing before wind derating, for both square and triangular layouts. Square spacing equals the radius; triangular spacing can extend to about 115 percent of the radius because the staggered geometry keeps the overlap. Round down in practice, then derate for wind.
| Head radius | Max square spacing | Max triangular spacing | Example after 20% wind derate (triangular) |
|---|---|---|---|
| 8 ft | 8 ft | ~9 ft | ~7 ft |
| 12 ft | 12 ft | ~14 ft | ~11 ft |
| 18 ft | 18 ft | ~21 ft | ~17 ft |
| 25 ft | 25 ft | ~29 ft | ~23 ft |
| 35 ft | 35 ft | ~40 ft | ~32 ft |
Reading the table: a spray head with a 12-foot radius on a calm rectangular strip can sit up to 12 feet from its neighbors in a square grid. The same head in an open, moderately windy lawn laid out triangularly starts at about 14 feet, then derates to roughly 11 feet once you account for wind.
Note: Always place heads at the corners and edges of an area first, then fill the interior. Perimeter heads define the shape; interior heads just maintain the overlap between them.
Turning Spacing Into a Layout
With spacing and overlap understood, you can position every head, count them per area, and roll them up into zones. See how spacing fits the larger workflow in how to design a sprinkler system, and turn your head counts into properly sized circuits with how to calculate sprinkler zones.
Getting spacing right by hand is doable but fiddly. To skip the geometry, design your system from a satellite photo and let the tool place heads at head-to-head spacing, staggered and derated, across your actual yard.