THE NUMBERS, EXPLAINED
How to use this calculator.
One millimetre over one square metre is one litre. Uniform application is assumed.
Start with your inputs
Enter area (m²), target water depth (mm), measured flow (l/min). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Area (m²) | 20 |
| Target water depth (mm) | 10 |
| Measured flow (L/min) | 10 |
A worked example
With the example inputs above, runtime (minutes) is 20. Change the inputs to explore your own scenario.
Putting the example numbers into the formula
Runtime (minutes)
(20) × (10) ÷ (10) = 20
Water required (L)
(20) × (10) = 200
| Result | Example answer |
|---|---|
| Runtime (minutes) | 20 |
| Water required (L) | 200 |
How this is calculated
Runtime (minutes)
a × b ÷ c
Water required (L)
a × b
Symbols and units
- a
- Area (m²)
- b
- Target water depth (mm)
- c
- Measured flow (L/min)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
One millimetre over one square metre is one litre. Uniform application is assumed.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Runtime (minutes); Water required (L). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: One millimetre over one square metre is one litre. Uniform application is assumed.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →