Drip Emitter Spacing Calculator – L/h, GPH

Drip design counts emitters, then multiplies by discharge. One hectare at 1.5 m row spacing holds 6,667 lateral-m; with emitters every 0.3 m that is 22,222 emitters, and at 2 L/h the zone demand is 44,444 L/h. If the wetted strip is 1.5 m wide, 44,444 L over 10,000 m² = 4.4 mm/h application — so a 6 mm net irrigation runs 6 ÷ 4.4 ÷ 0.9 (efficiency) ≈ 1.5 hours. Worked example in imperial: on 1,000 ft of row with emitters every 2 ft, 500 emitters at 0.5 GPH each draw 250 GPH for that lateral. Match emitter spacing to soil: sand 20–30 cm (water goes down), clay 40–60 cm (water spreads), and pick 1–2 L/h in tight soils, 2–4 L/h on sands.

1. 1

   Step 1

   Enter row spacing, row length and area for emitter counts.

2. 2

   Step 2

   Choose emitter discharge (1–4 L/h / 0.25–1 GPH).

3. 3

   Step 3

   Read emitters, total L/h and GPH per zone.

4. 4

   Step 4

   Enter target mm to get run time in hours.

• 1

  PC emitters above 2% slopes or 100 m laterals

• 2

  Filter 120–150 mesh; flush ends every 2–4 weeks

• 3

  Tape 8 mil for single-season, 15 mil+ for multi-year

• 4

  Pulse irrigation on sand: 3 × 1 h beats 1 × 3 h

• Mixing emitter rates inside one zone — uneven wetting

• Ignoring slope: non-pressure-compensating emitters gain 8–10% flow downhill per 5 m drop

• Spacing emitters for clay behavior on sand — columns of wet

• Running zones longer than the pump can sustain pressure