Why sprinkler head spacing matters
A sprinkler doesn't apply water evenly across its whole circle. It puts down the most water close to the head and less and less toward the edge of its throw, so a lone sprinkler leaves a ring of dry turf beyond its most effective range. The fix is overlap: place the next head close enough that its stronger, close-in water fills in the weaker, far edge of its neighbor's pattern.
Rain Bird's Landscape Irrigation Design Manual describes the first 60% of a sprinkler's radius as generally well watered on its own, with the water beyond that point tapering off. Head-to-head spacing, meaning each head is placed at its neighbor's radius, is the spacing most commonly used in landscape irrigation, and corresponds to 50% of the sprinkler's diameter. Spacing any wider than that leaves a gap neither head fully reaches.
| Wind | Square | Triangular | Rectangular (S / L) |
|---|---|---|---|
| 0–3 mph (calm) | 55% | 60% | 50% / 60% |
| 4–7 mph (breezy) | 50% | 55% | 45% / 60% |
| 8–12 mph (windy) | 45% | 50% | 40% / 60% |
These percentages are wind adjustments, not a substitute for a manufacturer's own chart. Different equipment throws water differently in wind. Where you have the manufacturer's own wind performance data for your specific head and nozzle, use that instead.
How this sprinkler head spacing calculator works
The calculator doubles your radius to get the sprinkler's diameter, looks up the wind percentage for your pattern and wind band from the table above, and applies it. Triangular and rectangular patterns then use a second step to find the row spacing.
1. Square pattern
Spacing and row spacing
S = Diameter × wind percentage (55%, 50% or 45%)
L = S
In a square grid the row spacing equals the head spacing. The weak point is the diagonal between opposite corners, which is farther than S.
Diagonal between opposite heads (informational)
Diagonal = S × 1.414 (√2, the diagonal of a square)
Rain Bird's manual notes that in a square pattern the opposite-corner distance runs over 70% of diameter even when S itself is at 50%, which is why the center of a square cell is the first place to check for dryness.
2. Triangular pattern
Spacing and row spacing
S = Diameter × wind percentage (60%, 55% or 50%)
L = S × 0.866
0.866 is the height of an equilateral triangle relative to its side, and is the exact factor Rain Bird's manual uses to turn head spacing into row spacing for this pattern. Alternate rows are offset sideways by half of S.
3. Rectangular (strip) pattern
Spacing and row spacing
S (across the wind) = Diameter × wind percentage (50%, 45% or 40%)
L (with the wind) = Diameter × 60% (fixed at every wind band)
This pattern fights wind by closing up the spacing in the crosswind direction while keeping the downwind row spacing constant, so it needs to know which way the prevailing wind blows across the site.
Rounding
Every result here is an exact multiplication of the radius you entered by a published percentage or geometric factor, so nothing is rounded to "about." Distances are shown to 2 decimal places in feet or 1 decimal place in meters, matching the precision used in the calculation.
When this calculator isn't the right tool
It tells you spacing, not how many heads or how much water that spacing needs. Use a different tool for:
- How many heads a given area needs at this spacing. See the sprinkler head count calculator.
- How much area a given spacing and radius will cover. See the sprinkler coverage calculator.
- The precipitation rate that results from your spacing and flow. See the sprinkler precipitation rate calculator.
- Checking an existing, already-installed system's uniformity rather than planning a new one. See the catch-can test calculator and the distribution uniformity calculator.
- Drip or micro-irrigation spacing, which follows plant spacing rather than a throw radius. See the drip emitter spacing calculator.
Sprinkler head spacing example
A rotor's performance chart lists a 25 ft radius at the site's working pressure. The lawn is a plain rectangle, so the designer uses a square pattern, and waters in the early morning when it's typically calm (0–3 mph).
- Diameter: 25 ft × 2 = 50 ft.
- Wind percentage: square pattern, calm wind → 55%.
- Head spacing (S): 50 ft × 0.55 = 27.50 ft.
- Row spacing (L): equal to S in a square grid = 27.50 ft.
- Diagonal check: 27.50 ft × 1.414 ≈ 38.89 ft between opposite corners, the point most likely to run dry first.
The same calculation in metric, with a triangular pattern
A 9 m radius rotor on an open slope, laid out in a triangular pattern, watering in a typically breezy afternoon (4–7 mph):
- Diameter: 9 m × 2 = 18 m.
- Wind percentage: triangular pattern, breezy wind → 55%.
- Head spacing (S): 18 m × 0.55 = 9.9 m.
- Row spacing (L): 9.9 m × 0.866 ≈ 8.6 m.
Compare the two: the triangular layout uses a larger percentage of the diameter than a square pattern would at the same wind band, and it has no diagonal weak spot to check, which is why it often takes fewer heads to cover the same open area.
Measuring your inputs
Radius of throw
Use the manufacturer's nozzle or performance chart for the exact model and nozzle you're using, read at your actual operating pressure. Radius changes with pressure: too little pressure shortens the throw below the rated figure, and too much can turn the stream into a fine mist that also falls short. If you don't have the chart, run one head on its own and measure the wet radius from the head to the edge of the spray with a tape measure.
Wind, without an anemometer
The wind bands above come from the same speeds meteorologists use to describe visible effects, based on the Beaufort scale published by the National Weather Service. Calm (0–1 mph) means smoke rises straight up; light air and light breeze (1–7 mph) mean you feel the wind on your face and see leaves rustle; a gentle breeze (8–12 mph) keeps leaves and small twigs in constant motion and extends a light flag. Watch your site at the time of day you actually plan to run the system, since afternoon wind is often stronger than a calm morning.
Laying the pattern out on the ground
Mark head locations with stakes and a tape measure or spacing string before digging. For a square pattern, keep every row and column at the same spacing S. For a triangular pattern, offset every other row sideways by half of S, so each head sits between two heads in the row before it. For a rectangular pattern, orient the rows so the fixed 60% row spacing runs with the prevailing wind and the tighter S spacing runs across it.
Choosing a spacing pattern
Square spacing is the simplest to lay out and fits areas with square or rectangular borders at 90° angles. Its weakness is the diagonal between opposite corners of each grid cell, which is farther than the head spacing itself and can leave a dry spot at the center of the square if the spacing is stretched.
Triangular spacing offsets each row, so there's no long diagonal gap to worry about. It suits open or irregularly bordered areas and, because it tolerates a slightly wider spacing at the same wind band, it can cover an area with fewer heads than a square layout.
Rectangular (strip) spacing keeps the row-to-row distance fixed while tightening the head-to-head distance across the wind. It fits narrow, open strips such as center medians or fairways where the wind consistently comes from one direction, and where the designer can orient the rows with that wind.
| Pattern | Best suited to | Main drawback |
|---|---|---|
| Square | Square or rectangular lawns, enclosed borders | Diagonal weak spot at the center of each cell |
| Triangular | Open or irregular areas, large turf areas | Needs offset rows, which some installers find harder to stake out |
| Rectangular (strip) | Narrow strips with a known, consistent wind direction | Only fights wind from one direction; a shifting wind still causes gaps |
Real sites often combine patterns: rectangular near a straight, windy boundary and triangular through the open middle of the same lawn, for example. Plot each area separately in this calculator and use the result that matches its own pattern and exposure.
What changes the recommended spacing
| Factor | Effect | What to adjust |
|---|---|---|
| Wind | Blows spray sideways before it reaches its full radius, shrinking effective coverage. | Pick the wind band that matches your actual watering time, not just a calm morning. |
| Operating pressure | Low pressure shortens the throw below the rated radius; high pressure can fog the spray and shorten it too. | Check pressure at the head against the manufacturer's rated range before entering a radius. |
| Sprinkler type | Doesn't change the percentage, but spray heads, rotors and multi-stream nozzles all have very different radii. | Use the radius for your specific head and nozzle, not a rule of thumb from a different type. |
| Slope | Water continues moving downhill after landing, effectively stretching coverage on the low side and shrinking it on the high side. | Consider tighter spacing or check-valve heads on slopes. |
| Site shape | Square boundaries often force a square pattern even where it's not the most efficient choice. | Use triangular or rectangular spacing wherever the area's shape allows it. |
| Obstructions | Trees, structures and slopes can block part of a head's throw, shrinking its effective radius locally. | Space more closely near obstructions, or add a supplemental head. |
Frequently asked questions
What is head-to-head sprinkler spacing?
Head-to-head spacing means each sprinkler's spray reaches the base of its neighbor, so every point in the yard gets water from more than one direction. It corresponds to a spacing equal to the sprinkler's radius, or 50% of its diameter. Rain Bird's Landscape Irrigation Design Manual identifies head-to-head, or 50% spacing, as the spacing most commonly used in landscape irrigation. Closer spacing costs more heads but improves uniformity; wider spacing leaves dry spots between heads.
How far apart should sprinkler heads be spaced?
It depends on the head's radius of throw, the layout pattern and local wind. In calm conditions, spray and rotor heads are typically spaced at 50 to 60% of their diameter depending on the pattern; in wind, that percentage drops so the spray still reaches the next head before it drifts off course. Enter your radius, pattern and typical wind above for the specific distance.
Does wind affect sprinkler head spacing?
Yes. Wind blows spray sideways before it reaches its full radius, so manufacturers recommend closing up the spacing in windy conditions to avoid dry strips. Rain Bird's design manual reduces the maximum spacing for a square pattern from 55% of diameter in calm conditions down to 45% at 8 to 12 mph, with similar reductions for triangular and rectangular layouts. Above about 12 mph, check the manufacturer's own wind performance data, since spray irrigation becomes inefficient at higher wind speeds.
What is the difference between square, triangular and rectangular spacing patterns?
Square spacing places heads at the corners of a square grid; it is simple to lay out but leaves a weak spot along the diagonal between opposite corners. Triangular spacing offsets alternate rows, removing that diagonal weak spot and generally allowing wider spacing for the same coverage. Rectangular, or strip, spacing keeps rows a fixed distance apart while closing up the spacing across the prevailing wind, which suits narrow, open strips exposed to wind from one side.
What is the row spacing in a triangular pattern?
In an equilateral triangular pattern, the distance between rows (L) is the head spacing (S) multiplied by 0.866, the height of an equilateral triangle relative to its side. For example, heads spaced 80 ft apart would have rows about 80 x 0.866, or roughly 69.3 ft, apart, following the example in Rain Bird's design manual. This calculator applies the same 0.866 factor to your own radius, pattern and wind inputs.
Can I space sprinkler heads wider than head-to-head to save money?
Stretching the spacing beyond head-to-head, beyond 50% of diameter, leaves gaps that no head fully reaches, and those gaps show up as dry, yellowing or dead turf between heads. It is rarely worth the small savings in head count, since owners typically respond by overwatering the whole zone to compensate for the dry spots. Use the recommended percentage for your pattern and wind instead of stretching the layout.
How do I find my sprinkler head's radius of throw?
Check the manufacturer's nozzle or sprinkler performance chart for the radius at your operating pressure, since radius changes with pressure and nozzle selection, not just the model name. If you don't have the chart, run one head and measure the wet radius with a tape measure from the head to the edge of the spray pattern. Measure at your system's actual working pressure, since low pressure noticeably shortens the throw.
The nozzle flow rate calculator can help cross-check a nozzle's rated numbers.
Who built and checked this calculator
Licensed Professional Engineer and Irrigation Association Certified Irrigation Designer with more than 20 years in irrigation design, system auditing and landscape water management. Full profile
How this page was checked
- Spacing percentages entered exactly as published in Rain Bird's design manual, for each pattern and wind band.
- Formulas and both worked examples, including the triangular 0.866 row-spacing factor, verified by hand.
- Unit conversions checked in both directions between US and metric.
Sources
- Rain Bird Corporation. Landscape Irrigation Design Manual, "Spacing sprinklers and calculating precipitation rates."
- Hunter Industries. Residential Sprinkler System Design and Installation Guide.
- National Weather Service, NOAA. Beaufort Wind Scale.