Project Results
Results appear above the form after every calculation.
Design Warnings
Review these items before using the estimate for construction.
- Pipe velocity exceeds the selected design limit.
- Available flow requires more zones than requested.
- Estimated overlap is very high.
- Application rate may exceed soil intake. Use cycle-and-soak.
Detailed Results
Review coverage, hydraulic performance, water demand, and cost details.
Layout and coverage
| Gross area | 2,400.00 ft² |
|---|---|
| Excluded area | 150.00 ft² |
| Net area | 2,250.00 ft² |
| Effective radius | 15.00 ft |
| Row spacing | 13.95 ft |
| Column spacing | 13.95 ft |
| Covered area | 2,250.00 ft² |
| Uncovered area | 0.00 ft² |
| Overlap area | 7,646.02 ft² |
| Overlap percentage | 339.8% |
Head schedule
| Total heads | 23 |
|---|---|
| Quarter-circle heads | 4 |
| Half-circle heads | 12 |
| Full-circle heads | 7 |
| Heads per zone | 6 |
| Maximum heads per zone | 6 |
| Flow per head | 3.00 GPM |
| Total installed flow | 69.00 GPM |
| Zone flow | 18.00 GPM |
| Distribution uniformity | 81.7% |
Hydraulic summary
| Mainline pressure loss | 3.07 PSI |
|---|---|
| Lateral pressure loss | 1.22 PSI |
| Elevation loss | 2.17 PSI |
| Total pressure loss | 23.46 PSI |
| Pressure at last head | 36.54 PSI |
| Pressure margin | 6.54 PSI |
| Pipe velocity | 6.68 ft/s |
| Suggested pipe size | 1.25 in |
Watering schedule
| Precipitation rate | 1.25 in/hr |
|---|---|
| Weekly runtime | 63.9 min |
| Runtime per watering day | 21.3 min |
| Cycle-and-soak cycles | 3 |
| Minutes per cycle | 7.1 min |
| Runoff risk | High |
| Weekly water use | 1,869 gal |
| Monthly water use | 8,121 gal |
| Annual water use | 97,188 gal |
Cost summary
| Head bodies | $149.50 |
|---|---|
| Nozzles | $74.75 |
| Pipe | $165.00 |
| Fittings | $69.00 |
| Valves | $140.00 |
| Materials subtotal | $932.85 |
| Labor | $720.00 |
| Tax and waste | $150.19 |
| Contingency | $205.30 |
| Annual water cost | $437.35 |
Adjustment factors
| Wind spacing reduction | 4.0% |
|---|---|
| Exposure reduction | 3.0% |
| Slope reduction | 0.0% |
| Base spacing | 15.00 ft |
| Corrected spacing | 13.95 ft |
| Requested zones | 1 |
| Zones required by flow | 4 |
| Final zone count | 4 |
Interactive Layout Planner
Drag generated heads, add custom heads, remove heads, and inspect coverage circles.
Example Data Table
Sample layouts demonstrate how radius, spacing, flow, and zones interact.
| Application | Head type | Typical radius | Spacing pattern | Pressure range | Design note |
|---|---|---|---|---|---|
| Small residential lawn | Fixed spray | 8–15 ft | Square head-to-head | 25–35 PSI | Use matched precipitation nozzles. |
| Medium open lawn | Rotary nozzle | 15–35 ft | Triangular or square | 35–45 PSI | Good choice for lower precipitation. |
| Large turf area | Rotor | 25–60 ft | Square or triangular | 40–65 PSI | Check available zone flow carefully. |
| Narrow planting strip | Strip spray nozzle | 4–15 ft | Rectangular | 25–35 PSI | Control overspray onto pavement. |
| Shrub or garden bed | Micro-spray | 4–15 ft | Custom | 15–30 PSI | Use filtration and pressure regulation. |
Formula Used
The calculator combines geometric, hydraulic, scheduling, and cost formulas.
The formula uses GPM and feet, then converts metric results.
How to Use This Calculator
Follow these steps for a practical preliminary irrigation layout.
1. Define the site
Select the area shape. Enter dimensions and excluded surfaces. Use polygon points for irregular boundaries.
2. Select the head
Choose the head type. Enter radius, flow, pressure, nozzle model, and precipitation information.
3. Set spacing rules
Use head-to-head coverage initially. Adjust spacing for wind, slopes, boundaries, and manufacturer limits.
4. Enter supply data
Use measured static pressure and available flow. Add pipe lengths, elevation, and device losses.
5. Review warnings
Check pressure margin, pipe velocity, required zones, dry areas, overlap, and runoff risk.
6. Export the plan
Download CSV data, print a PDF, save the project, or export the canvas image.
Understanding Spray Head Spacing
Good spacing supports uniform coverage and predictable water application.
Why head-to-head coverage matters
Spray patterns usually apply less water near their outer edge. Adjacent heads should reach each neighboring head. This overlap reduces weak coverage between individual patterns.
Rated radius assumes suitable pressure and calm conditions. Wind can shorten or distort spray distribution. Slopes can increase runoff before water reaches roots.
Square and triangular layouts
Square layouts place heads along aligned rows and columns. They are simple to install and measure. Their diagonal gaps require reliable head-to-head performance.
Triangular layouts offset every second row. This arrangement often improves overlap in open areas. Row spacing commonly uses about eighty-seven percent of radius.
Pressure and flow considerations
Every nozzle needs a specific operating pressure. Pipe friction reduces pressure as flow travels downstream. Elevation changes also alter pressure at remote heads.
Available flow limits heads operating together. Large layouts usually require several control zones. Each zone should group heads with similar precipitation rates.
Preventing overspray and runoff
Use quarter arcs at corners and half arcs along boundaries. Keep full circles inside larger open areas. Narrow strips need purpose-built strip nozzles.
Application rate should remain below soil intake capacity. Clay and compacted soils accept water slowly. Cycle-and-soak scheduling helps water infiltrate between shorter cycles.
Use manufacturer data before installation
This calculator provides useful preliminary quantities and checks. Actual nozzle performance varies with pressure and model. Verify final spacing using current manufacturer performance charts.
Measure dynamic pressure while the zone is flowing. Confirm backflow rules and local water restrictions. Professional review improves reliability for complex systems.
Frequently Asked Questions
Common questions about spray head layouts and calculations.
What is head-to-head spacing?
It means each sprinkler reaches the next sprinkler. The spacing normally equals the effective spray radius.
Should spacing equal the catalog radius?
Not always. Wind, low pressure, slopes, and obstructions can require closer spacing.
Is triangular spacing better than square spacing?
Triangular spacing can improve overlap in open areas. Square spacing remains easier near straight boundaries.
Can different nozzle types share one zone?
Only when their precipitation rates match closely. Mixed rates can cause dry or overwatered sections.
How many heads can one zone support?
Divide available flow by head flow. Also confirm pressure remains adequate under simultaneous operation.
Why does pipe size matter?
Small pipes increase velocity and friction loss. Excess loss reduces pressure at distant heads.
How does slope affect irrigation?
Steep slopes increase runoff risk. Shorter cycles and closer spacing may improve performance.
How accurate is the cost estimate?
Accuracy depends on entered unit prices and labor assumptions. Local bids may differ significantly.
Can the calculator design irregular areas?
Yes. Enter polygon coordinates and excluded area. The visual grid remains an approximate planning view.
Does the PDF button create a file?
It opens the browser print dialog. Choose the browser option that saves output as PDF.
Is this a final engineering design?
No. Confirm all values with manufacturer data, field tests, codes, and qualified professionals.
Design Disclaimer
This report is a preliminary estimate. Verify final design conditions before purchasing or installing materials.