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Planting Calculators

Watering Calculator

Water needed for a garden or lawn, per session and per week.

Enter values

Results update as you type.

Result

Water per week

1,000 litres

Water deeply and less often — a light daily sprinkle keeps roots shallow and makes plants less drought-tolerant.

Per session
500 litres
Watering time per session
41.7 minutes
Depth to apply
20 mm
Rainfall credit
250 litres
Watering cans (10 L)
50
Per month
4,350 litres

About the Watering Calculator

Water needed for a garden or lawn, per session and per week.

Also known as: garden watering calculator, how much to water plants, irrigation amount, watering schedule.

How to use this calculator

  1. Enter area, planting, watering sessions per week, rainfall this week and the other fields.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

litres = area × millimetres needed (1 mm over 1 m² = 1 litre)

Worked example

Using the values pre-filled in the calculator above:

  • Area = 50 m²
  • Planting: Lawn (25 mm a week)
  • Watering sessions per week = 2
  • Rainfall this week = 5 mm
  • Hose flow rate = 12 L/min

the calculator returns:

  • Water per week: 1,000 litres
  • Per session: 500 litres
  • Watering time per session: 41.7 minutes
  • Depth to apply: 20 mm