Sprinkler spacing calculator
Choose a nozzle and the radius you want it to throw. You get the head-to-head spacing, the nozzle's adjustable range and the flow of each arc — and, with a lawn size, the layout Topoform's engine draws with that nozzle.
Head-to-head spacing
The calculator assumes a plain rectangle. In the app you trace your real lawn, mark beds and paths, and the same engine places the heads, zones and pipes and builds a parts list.
Draw your actual yardHead to head: the one spacing rule that matters
The most common sprinkler mistake is spacing heads so their sprays just touch. Water does not land evenly along a spray: most of it falls in the near and middle part of the throw, and only a little reaches the far end. If two heads only meet in the middle, the strip between them gets far less water than the ground near each head. The lawn shows it within weeks: green rings around every head and dry bands between them.
The fix is head-to-head spacing. Each head throws all the way to the next head, so every patch of lawn is reached by two or more sprays and the light outer edge of one spray is filled in by its neighbour. Put simply: the distance between heads equals the throw radius. Topoform's layout engine uses exactly that — the spacing between its grid of heads is the nozzle's radius — and this calculator reports the same number.
The radius range of each nozzle
Every MP Rotator nozzle can be turned down with its radius adjustment screw, so each model covers a range rather than one fixed throw. These are Hunter's published ranges as stored in Topoform's catalog:
- MP800SR: 6–12 ft (1.8–3.7 m) — for narrow side yards and small areas.
- MP1000: 8–15 ft (2.5–4.5 m) — for small lawns and strips.
- MP2000: 13–21 ft (4.0–6.4 m) — the all-round size for a typical back lawn.
- MP3000: 23–30 ft (6.9–9.1 m) — for large open lawns.
Enter a radius inside the range of the nozzle you picked; the calculator tells you if it is out of range. Leave the radius empty to use the nozzle's standard radius, the one Topoform's Auto-design places it at. The strip and corner nozzles are not in the list: strip nozzles spray a fixed rectangle (for example 5 × 30 ft for the side strip) rather than a circle, so there is no radius to space by.
Turning the radius down
The radius screw trims a nozzle's throw within its range, which is handy for fitting a head to a lawn edge. If you find yourself cutting a nozzle down to the bottom of its range, the next size down is usually the better choice: it fits the space at its natural throw and keeps the watering rate in step with its neighbours. This is why Topoform's Pick nozzle size per area option chooses a smaller model for narrow strips instead of throttling a big one.
Flow per arc
The calculator also lists the flow of one head at each arc it can be set to. MP Rotators are matched-precipitation nozzles: the flow follows the arc, so a half circle uses half the water of a full circle and a quarter circle uses a quarter. Each head puts down water at the same rate whatever its arc, which is what lets edge, corner and middle heads share one zone. Hunter rates these flows at 2.8 bar (41 psi); for the MP2000, a full circle is 1.47 GPM (5.6 L/min).
You will need those flows next: add them up per zone in the zone calculator to see how many heads one zone can run on your supply.
Square or triangle?
On a large open lawn, heads can sit on a square grid or a staggered (triangular) grid; both work at head-to-head spacing. The knowledge base Topoform's engine was built from notes that the pattern changes how much water lands per hour, which is one more reason to keep one layout style per zone. Topoform's engine lines its grid up with the dominant edge of your lawn and puts half and quarter circles along the edges, so the coverage stays head to head right up to the border.
See it laid out
Add a lawn width and length to see the layout Topoform's Auto-design draws for that rectangle using only the nozzle you picked, at its standard radius. The preview shows each head's coverage circle to scale, so the overlap is easy to see. To compare models, change the nozzle and run it again; for the count with the nozzle size chosen per area, use how many sprinklers do I need.
From spacing to a real plan
Spacing is the first decision, not the last. A real yard has curves, a house, beds and paths, and it matters where your water comes in. In the Topoform app you trace the lawn, mark what not to water and run Auto-design: it places the heads at head-to-head spacing on your real shape, groups them into zones that fit your supply, routes the pipes and builds a parts list. Every head can still be moved, re-aimed or changed by hand.
Questions and answers
What is head-to-head spacing?
Placing sprinklers so the spray of each head reaches the next head. The distance between heads equals the throw radius, which gives every patch of lawn overlapping coverage and even watering.
Can I space sprinklers farther apart to save heads?
Not without dry patches. Most of the water lands in the inner part of the throw, so heads spaced wider than their radius leave under-watered bands between them.
Should I turn the radius down or use a smaller nozzle?
A small reduction to fit an edge is fine. For a much shorter throw, a smaller nozzle at its natural radius is the better fit and keeps pace with its neighbours.
Why are the strip nozzles not in the list?
They spray a fixed rectangle instead of a circle, so there is no radius to space them by. The how-many-sprinklers calculator uses them automatically on narrow strips.
Draw your actual yard
The calculator assumes a plain rectangle. In the app you trace your real lawn, mark beds and paths, and the same engine places the heads, zones and pipes and builds a parts list.