Water Use Efficiency & Crop per Drop
Measures kg/m³
Enter yield and water used to get water productivity in kg per m³ and kg per mm, plus litres of water per kg of produce — so you can measure and lift crop per drop.
Yield & water applied
Next: lift WUE with drip/mulch to cut losses, deficit irrigation at less sensitive stages, and matching variety and agronomy to the water you have, rather than just applying more.
WUE varies by crop, climate and whether you count irrigation only or rainfall too; compare like with like before drawing conclusions.
Water use efficiency — key facts
- WUE
- yield ÷ water used
- Water applied
- depth (mm) × area (m²) ÷ 1000
- 1 mm over 1 m²
- = 1 litre of water
- kg/m³
- crop per cubic metre
- L/kg
- inverse of kg/m³
- Lift WUE
- drip, mulch, deficit irrigation
- Compare
- like with like (rain in or out)
- Privacy
- Runs in your browser; nothing uploaded
More crop per drop, not just more water
Yield alone hides whether water is being used well. Water use efficiency divides what you harvest by the water it took — yield ÷ water used — so a field that grows the same crop on less water scores higher. Measure water as a depth over an area (one millimetre over a square metre is one litre, so it converts straight to m³) or enter a metered volume. The result, in kg/m³, kg/mm and litres per kg, is the honest scorecard for how productively your water turns into harvest.
This tool reports water used in m³, kg per m³, kg per mm, litres per kg and an efficiency band. Use it to compare seasons, fields and practices, and to test whether a change is really helping. The proven ways to lift WUE are to cut losses with drip and mulch, apply deficit irrigation at less-sensitive growth stages, and match the variety and agronomy to the water you have. Pair it with the Pan Evaporation ET, Irrigation Scheduling and Drip Water Saving tools for a water-tight plan.
Score your water
See kg/m³ and litres per kg of produce.
Depth or volume
Enter mm over an area or a metered m³.
Test what works
Compare practices on crop per drop, not yield alone.
Cut the losses
Drip, mulch and deficit irrigation lift WUE.
Frequently Asked Questions
What is water use efficiency?+
Water use efficiency (WUE), also called water productivity, is the yield you harvest per unit of water used: WUE = yield ÷ water used. It answers "how much crop per drop?" Expressed as kg per m³ or kg per mm, it lets you compare fields, seasons and practices on how productively they turn water into harvest rather than just on total yield.
How is water use efficiency calculated?+
Divide the crop yield by the water used over the season. If yield is in kilograms and water in cubic metres, WUE is kg/m³. The tool also reports kg per mm of water depth and its inverse — litres of water per kilogram of produce — which is an intuitive way to see how water-hungry a crop or practice is.
How do I convert irrigation depth to a water volume?+
Water applied (m³) = depth (mm) × area (m²) ÷ 1000, because one millimetre of water spread over one square metre is one litre. So 100 mm over a hectare (10,000 m²) is 1,000 m³. You can enter water as a depth and area, or type a measured volume directly if you metered it.
What does kg/m³ actually mean here?+
It's the kilograms of harvested produce per cubic metre (1,000 litres) of water used. Higher is better. Typical values vary widely by crop and climate — cereals might be in the low single digits of kg/m³ while high-value vegetables differ — so the most useful comparison is against your own past seasons and neighbouring practices.
What is the difference between kg/m³ and L/kg?+
They are inverses of the same thing. kg/m³ tells you how much crop one cubic metre of water grows; litres per kg tells you how much water it took to grow one kilogram of produce. The L/kg figure is handy for water-footprint conversations, while kg/m³ is the usual agronomic productivity measure.
How do I improve water use efficiency?+
Lift WUE by cutting losses rather than just applying more water: switch to drip and use mulch to reduce evaporation, apply deficit irrigation at growth stages that are less sensitive to water stress, and match the variety and agronomy to the water you actually have. Healthy soil, weed control and good nutrition all help each drop produce more.
What is deficit irrigation?+
Deficit irrigation deliberately applies less water than full crop demand, concentrating the savings at stages where the crop tolerates mild stress with little yield loss, while keeping water up at sensitive stages like flowering and grain or fruit fill. Done well it can raise water productivity (kg/m³) even if total yield dips slightly.
Should I include rainfall in the water used?+
Be consistent and compare like with like. You can compute WUE on irrigation water only (useful for judging the irrigation system) or on total water including effective rainfall (useful for overall crop water productivity). Just don't mix the two between fields or seasons, or the comparison will mislead you.
Does this work for any crop or unit?+
Yes. Enter yield in your preferred mass unit and water as a depth over an area or as a measured volume, and the tool reports kg/m³, kg/mm and L/kg. It works for cereals, vegetables, fruit and fodder — the productivity ratio is universal, only the typical values differ between crops.
How accurate are the figures?+
They're as accurate as your inputs. Metered water and weighed yield give reliable productivity; estimated depths and eyeballed yields give ballpark figures. Use WUE to compare and steer — track it across seasons and treatments to see whether a change in irrigation or agronomy is genuinely producing more crop per drop.