Garden Watering Calculator
Litres a garden needs each week, how long to run the hose, and what it costs over a year.
Results
Volume
800
L/semana
Minutes
80.0
min
Cost
1.440
Cost
74.88
Volume
41.60
m³/a
What this tool does
One millimetre of water over one square metre is exactly one litre, which makes garden watering easy to reason about once you think in millimetres like rainfall. Most established gardens want around 25 mm a week in summer, delivered in one or two deep soakings rather than daily sprinkling — shallow watering keeps roots near the surface where they dry out fastest.
Formula
litres = area × mm of watering (1 mm over 1 m² = 1 L)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
a | Area | m² |
mm | Watering depth | mm/semana |
rn | Annual rainfall | mm/semana |
fr | Flow rate | L/min |
pr | Water price | /m³ |
L | Volume | L/semana |
TM | Minutes | min |
CW | Cost | — |
CY | Cost | — |
M3 | Volume | m³/a |
Worked example
- Area40 m²
- Watering depth25 mm/semana
- Annual rainfall5 mm/semana
- Flow rate10 L/min
- Water price1.8 /m³
- Volume800 L/semana
- Minutes80.0 min
- Cost1.440
- Cost74.88
- Volume41.60 m³/a
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.