Yield per Watt
Worked example: 450 g from 600 W → 0.75 g/W — press Try an example to run it live, then adjust anything.
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Yield per Watt explained
Grams per watt is the indoor grower's headline efficiency figure, and it is both genuinely useful and routinely abused. It divides dry harvested weight by the lighting power that produced it, so it folds together fixture efficacy, canopy management, genetics and grower skill into a single comparable number.
Realistic figures: an inexperienced grower under older lighting might see 0.5 g/W. A competent room under modern LED reaches 1.0–1.5. Well-run commercial operations report 1.5–2.0, and claims meaningfully above 2.0 deserve scrutiny. The most common inflation is quoting wet weight, which runs four to five times the dry figure — a "3 g/W" claim is very often 0.7 g/W of actual dry product.
The deeper limitation is that the denominator is the wrong variable. Yield does not track electrical watts; it tracks photons delivered to the canopy, which is why the same grower switching from HPS to LED sees grams per watt jump without changing anything about horticulture. The honest modern metric is grams per mole of delivered light, which separates the fixture's efficiency from the grower's. Grams per watt remains useful for one thing it does well: comparing two rooms that pay the same electricity tariff.
Yield per Watt formula
- = Yield per watt (g/W) (g/W)
- = Dry yield (g)
- = Lighting power (W)
Missing one of these? Work it out first, then come back
- Dry yield — Crop Yield per Unit Area, CO₂ to Enrich a Sealed Room
- Lighting power — Lighting Power Density, Power (P = W/t)