GardenCalcs.uk
Drip Irrigation Calculator — Pipe & Dripper Layout
Calculate dripper spacing, flow rates, and pipe lengths for drip systems.
How We Calculate This
Total pipe = Row length × Number of rows. Drippers per row = Row length ÷ Spacing + 1 (the +1 counts the emitter at the very start of the run).
Total system flow = Drippers × Flow rate per dripper. This is how a drip system's demand is sized: the flow you need at the tap is simply the sum of every emitter's output.
Wetted area assumes rows are laid one dripper-spacing apart — the layout UK suppliers recommend so each 30 cm wetting cone overlaps its neighbour (e.g. 30 cm drippers ⇒ rows 30 cm apart). If you space rows wider than the drippers, enter a higher Watering Rate to compensate.
Run time = (Wetted area × Watering rate) ÷ System flow. The default 4 L/m² roughly matches a UK summer crop loss of ~4 mm/day (1 mm over 1 m² = 1 L), so a typical session lands in the usual 30–60 minute window.
Frequently Asked Questions
For veg gardens: 30 cm. For shrubs: 45-60 cm. For close-planted beds: 20-30 cm. Sandy soil needs closer spacing than clay.
2 L/hr is standard for most garden use. 4 L/hr for thirsty plants or sandy soil. 1 L/hr for containers or precise watering.
Most drip systems work at 1-2 bar. Use a pressure reducer if mains pressure is higher. Low-pressure kits (0.5 bar) work from water butts.
Typically 30-60 minutes per session, 2-3 times per week in summer. Adjust based on soil and plant needs.
Yes, but you need a low-pressure system. Standard drip kits need 1-2 bar. Water butt gravity systems produce about 0.2-0.5 bar, so use low-pressure drippers designed for rain barrels.
Related Calculators
Water Pressure Calculator
Calculate water pressure and flow rate for garden irrigation systems.
Water Butt Size Calculator
Calculate the ideal water butt size based on your roof area and rainfall.
Irrigation Timer Calculator
Work out watering duration and frequency for your irrigation system.
Watering Can Calculator
Calculate how many watering cans you need for your garden beds.
Hose Flow Rate Calculator
Estimate water flow rate based on hose diameter and pressure.
Was this calculator helpful?
Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.