Square vs Triangular Sprinkler Spacing

Square vs triangular sprinkler spacing is a choice between two grid patterns for the same heads. In a square layout, head spacing and row spacing are equal. In a triangular layout, rows are offset and row spacing is head spacing multiplied by 0.866, which gives tighter rows, more even overlap and a higher precipitation rate from the same flow.

What square spacing means

Square spacing puts each head at the corner of a square. If head spacing is 5 m, row spacing is also 5 m, and the layout is 5 m by 5 m. The next head along a row is 5 m away, and the head diagonally across the square is about 7.07 m away. That diagonal distance is the key weakness of the pattern. Area per head is head spacing multiplied by row spacing, so at 5 m spacing it is 25 square metres per head. Precipitation rate is full circle flow multiplied by 60, divided by head spacing multiplied by row spacing. With a full circle flow of 10 litres per minute at 5 m by 5 m, the rate is 10 multiplied by 60, divided by 25, which is 24 mm per hour.

What triangular spacing means

Triangular spacing keeps head spacing along a row the same, but it shifts every second row by half a head spacing and pulls the rows closer together. Row spacing is head spacing multiplied by 0.866. At 5 m head spacing, row spacing is 4.33 m. At 4 m head spacing, row spacing is 3.46 m. At 6 m head spacing, row spacing is 5.20 m. Every head has six near neighbours at about the same distance. In a triangular grid the nearest head in the next row is also about one head spacing away. That even distance is the reason the calculator page says triangular spacing gives more even coverage.

Square vs Triangular Sprinkler Spacing: Row Spacing and Area per Head Compared

The table below uses the same head spacing in both layouts. Row spacing in the triangular column is head spacing multiplied by 0.866. Area per head is head spacing multiplied by row spacing.

Head spacing m	Square row spacing m	Triangular row spacing m	Square area per head sq m	Triangular area per head sq m
4	4.00	3.46	16.00	13.86
5	5.00	4.33	25.00	21.65
6	6.00	5.20	36.00	31.18

Triangular row spacing is about 13.4 percent smaller than square row spacing at the same head spacing, because 1 minus 0.866 is 0.134. Triangular area per head is also about 13.4 percent smaller. That smaller area per head is tighter packing, which gives the more even overlap. At the same head spacing, triangular spacing gives less area per head, as the table shows. The benefit the calculator page notes comes from the other direction. Because every neighbour is about one head spacing away, you can often use a slightly wider head spacing in a triangular layout and still keep even overlap.

Precipitation rate compared

Precipitation rate is full circle flow multiplied by 60, divided by head spacing multiplied by row spacing. The table below uses the verified example flow of 10 litres per minute.

Head spacing m	Square rate mm per hour	Triangular rate mm per hour
4	37.5	43.3
5	24.0	27.7
6	16.7	19.2

At 5 m spacing, the square rate is 24 mm per hour, which is the verified worked example. The triangular rate is 600 divided by 21.65, which is 27.7 mm per hour. A higher rate means the same depth is applied in less time, but the lawn must take water faster without runoff. The calculator page notes that most lawns take 12 to 25 mm per hour without runoff, and that clay soils prefer the lower end of that range.

The imperial example below is a separate worked example, labelled as an example input worked through the same formulas. It uses 2.5 gallons per minute at 15 ft spacing. The square rate is 1.07 inches per hour, which matches the verified imperial example. The triangular rate, at about 13 ft row spacing, is 1.23 inches per hour.

Run time is depth divided by precipitation rate. For the verified example, 12 mm at 24 mm per hour takes 30 minutes square, and about 26 minutes triangular. If you change pattern without changing run time, you will apply more depth than planned. The irrigation run time calculator can help once you know the new rate.

The weak point of a square grid

The weak point of a square grid is the centre of four heads. Picture four heads at the corners of a 5 m square. The point in the middle is 3.54 m from each head, because half the diagonal of a 5 m square is 3.54 m. The point midway between two heads along an edge is only 2.5 m from each of those two heads. If each head throws 5 m, both points are inside the throw, but the centre relies on heads at a longer distance, where spray is thinner. Spray is usually stronger near the head and weaker near the edge of the throw, so the centre gets less overlap. Wind and low pressure reduce real throw, so the centre gets weaker still. Triangular spacing shortens that centre distance to about 2.89 m at the same spacing.

Why triangular gives more even coverage

Triangular spacing gives more even coverage because the distance to the nearest head is more nearly the same in every direction. In a square grid, a point can be 2.5 m from the nearest head along a row, or 3.54 m from the nearest heads at a square centre. In a triangular grid, the nearest heads are spaced more evenly around each point, so the overlap is more balanced. The offset is the key. By shifting every second row by half a spacing, the heads in the next row sit in the gaps of the row in front.

Where square fits better

Square spacing fits better where the lawn itself is square or rectangular, with straight edges, straight paths and straight beds. Heads along an edge can sit in a straight line, parallel to the edge, and corners can be placed with a simple right angle. A triangular offset along an edge can leave a staggered edge line.

Choosing between the two

Choose by lawn shape first, then by evenness, then by rate. If the lawn is rectangular with straight edges, square spacing is a sound default. If the lawn is open and wide, triangular spacing is a sound default. Check the precipitation rate next, against the range the calculator page gives for lawns, 12 to 25 mm per hour, with clay soils preferring the lower end. If the triangular rate is above that range, consider a wider spacing, a lower flow, or a split run.

Check the throw last. Coverage of one head is pi multiplied by radius squared multiplied by arc divided by 360. For a full circle head throwing 5 m, that is about 79 square metres. For a full circle head throwing 15 ft, that is about 707 square feet. Use the sprinkler coverage calculator to work the rate and run time for your own spacing and flow, and use the sprinkler calculator if you need to check head numbers.

Common mistakes

1. Using the same row spacing in both patterns, instead of 0.866 times head spacing for triangular rows.
2. Forgetting that the rate changes when the pattern changes, from 24 to 27.7 mm per hour at 5 m spacing.
3. Mixing nozzles without checking matched precipitation, so one head applies more water than its neighbours.
4. Trusting the catalogue throw on a windy site or at low pressure, which leaves dry centres in a square grid.
5. Placing heads by eye along a curved edge, instead of placing edge heads first and then filling the middle with the grid.

How to check the real rate with a catch cup test

A catch cup test confirms the real rate on your lawn, after wind, pressure and nozzle differences have had their effect. Place straight sided cups across the lawn, covering the middle and the points between heads. Run the zone for 15 minutes, measure the average depth in the cups, and multiply by 4 for the hourly rate. That is the method the calculator page gives. Compare the measured rate with the calculated rate. If the cups show similar depths, the pattern is working. If the measured rate is much lower, check pressure and throw first. If some cups are much fuller than others, check the pattern, the offset and nozzle flows.

Frequently Asked Questions

Q: What is the main difference between square vs triangular sprinkler spacing?
A: In square spacing, head spacing and row spacing are equal, so a 5 m head spacing gives 5 m row spacing. In triangular spacing, rows are offset and row spacing is head spacing multiplied by 0.866, so a 5 m head spacing gives 4.33 m row spacing.

Q: Does triangular spacing use more water?
A: No, not for the same depth over the same lawn. Triangular spacing applies the same flow over a smaller area per head, so the rate is higher and run time is shorter. At 5 m spacing, the square rate is 24 mm per hour and the triangular rate is 27.7 mm per hour, so 12 mm takes 30 minutes square and about 26 minutes triangular.

Q: Which layout is best for a rectangular lawn?
A: Square spacing is often the best fit for a rectangular lawn with straight edges, because edge heads sit in a straight line.

Q: Why is the centre of four heads dry in a square grid?
A: The centre of four heads is further from its nearest heads than a point midway along an edge. At 5 m spacing, the centre is 3.54 m from each head, while the edge midpoint is 2.5 m from its two nearest heads. The spray is weaker near the edge of the throw, so the centre gets less overlap.

Q: How do I work out row spacing for triangular spacing?
A: Multiply head spacing by 0.866. For 4 m head spacing, row spacing is 3.46 m. For 5 m head spacing, row spacing is 4.33 m. For 6 m head spacing, row spacing is 5.20 m. Mark the second row offset by half a head spacing, and check row spacing with a tape.

Q: Should I change run time if I change from square to triangular spacing?
A: Yes. Run time is depth divided by precipitation rate, and the rate rises when row spacing falls. At 5 m spacing with 10 litres per minute, the rate rises from 24 mm per hour to 27.7 mm per hour, so 12 mm takes about 26 minutes instead of 30 minutes.