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Sprinkler System Calculator

Sprinkler System Calculator

Create a preliminary lawn irrigation plan from area, sprinkler radius, overlap efficiency, head flow, available water flow, pipe allowance, and installation costs.

22-calculator project library Reviewed 2026-07-25Calculations run privately in your browser

Enter project details

Example values are prefilled

Coverage and water

Irrigated length

Irrigated width

Head type

Nominal throw radius

Effective coverage after overlap

Flow per head

gpm

Available design flow

gpm

Material and labor

Price per head

Valve/manifold allowance per zone

Controller and sensor allowance

Pipe/fittings per linear ft

Installation labor per head

Location and tax assumptions

The location factor adjusts labor only. Replace all default prices with actual local quotes before purchasing.

Local labor-cost factor

A coarse planning adjustment—not a ZIP-code quote.

Sales tax on materials

Enter the tax rate that applies to taxable materials.

All default prices are editable examples. Cost scenarios vary the entered plan; they do not represent bids or guarantees.

How to use this sprinkler system calculator

Estimate sprinkler heads, zones, flow, pipe, valves, materials, labor, and project cost.

Formula

Effective area per head = π × radius² × overlap efficiency. Heads = lawn area ÷ effective head area, rounded up. Zones = total head flow ÷ available design flow, rounded up.

Worked example

Example: A 5,000 sq ft lawn using 15 ft spray heads at 55% effective coverage yields about 389 sq ft per head, or roughly 13 heads before layout adjustments.

Accuracy and limitations

Hydraulic design requires verified static/dynamic pressure, pipe sizing, elevation, backflow rules, matched precipitation, head-to-head spacing, and a scaled site plan.

Frequently asked questions

Why is effective coverage less than the circle area?

Sprinklers overlap for even watering, and boundaries prevent using the full circular pattern.

Can spray heads and rotors share a zone?

They often have different precipitation rates and generally should be designed separately.

Is available flow the same as bucket-test flow?

A bucket test is a useful screen, but final design should account for operating pressure and supply limitations.