Drip Irrigation Calculator
Design your drip irrigation system.
Enter number of plants, emitter flow rate, and water pressure to calculate system requirements and run time.
Drip irrigation flow calculation ensures your system delivers the right amount of water to each plant without over- or under-watering. The key is matching emitter flow rate and run time to your plants’ water requirements.
The Formula:
Run Time (minutes) = (Plant water need in liters) / (Emitter flow rate in L/hour) × 60
Total flow rate (L/hour) = Number of emitters × Emitter flow rate
Emitter Flow Rate Reference:
| Emitter Color (Netafim standard) | Flow Rate |
|---|---|
| Black | 1 L/hour |
| Red | 2 L/hour |
| Blue | 4 L/hour |
| Green | 8 L/hour |
Plant Water Requirement Reference:
| Plant Type | Daily Need (liters, summer) |
|---|---|
| Herbs | 0.5–1 L |
| Tomatoes | 2–3 L |
| Peppers | 1.5–2 L |
| Squash | 3–5 L |
| Trees (established) | 10–40 L |
Worked Example:
12 tomato plants, each needing 2.5 L/day. Using 2 L/hour emitters, 2 emitters per plant:
- Total emitters: 24
- Total system flow: 24 × 2 = 48 L/hour
- Total water needed: 12 × 2.5 = 30 L/day
- Run time: 30 / 48 × 60 = 37.5 minutes per day
System Pressure:
Drip emitters need 0.5–2.0 bar (7–30 PSI). Pressure regulators are essential if your main line exceeds 3 bar.
Practical Tips:
- Run drip lines early morning — minimizes evaporation and fungal disease risk
- Flush lines monthly — emitters clog with mineral deposits and organic matter
- Use a filter (130-mesh minimum) before any drip zone to prevent emitter blockage
- In clay soil, reduce flow rate — clay absorbs slowly and water pools around roots