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Drip Irrigation Calculator — Pipe & Dripper Layout
Calculate dripper spacing, flow rates, and pipe lengths for drip systems.
Length of one drip run, end to end, in metres.
How many parallel drip runs feed the bed.
Gap between emitters along the pipe: 30 cm for veg, 45–60 cm for shrubs, 20 cm for sandy soil.
Emitter output: 2 L/hr is the standard garden dripper, 4 L/hr for thirsty plants or sandy soil, 1 L/hr for containers.
Litres per m² per session. Default 4 L/m² suits most gardens.
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.
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Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.