Garden Watering Calculator

Work out how much water your garden needs per week and per day, based on area and weather conditions.

Water need per week
1,250 liters
50 m² × 25 mm/week
Per day
179 liters
Equivalent rainfall
25 mm/week
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How to use the garden watering calculator

  1. Enter the garden area to be watered, in square meters.
  2. Choose the weather conditions — dry, hot weather gives a higher water need than cool, rainy weather.
  3. The calculator shows how much water the garden needs per week and per day.

How the water need is calculated

1 mm of rainfall over 1 m² equals 1 liter of water. The calculator multiplies the area by the recommended rainfall equivalent per week for the chosen weather conditions:

Water (liters/week) = Area (m²) × Amount (mm/week)

This figure covers natural rainfall and any watering together — if the garden gets a lot of rain during the week, you need to water correspondingly less yourself.

Note: Actual need varies with soil type, plant type and wind/sun exposure — sandy soil dries out faster than clay soil and may need more frequent watering.
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Frequently asked questions

How much is 1 mm of rainfall in liters?

1 mm of rainfall equals 1 liter of water per square meter. If your garden has an area of 50 m², 1 mm of rainfall equals 50 liters of water spread across the whole area.

Should I water every day or less often with more each time?

Less frequent, more thorough watering is usually best. It encourages plants to develop deeper roots, while frequent, shallow watering can give a weaker root system and increased water need over time.

How does soil type affect watering needs?

Sandy soil drains quickly and holds less moisture, so it often needs more frequent watering. Clay soil holds onto water longer, but can become hard and water-repellent if it dries out completely.

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