Light running cost & yield metrics
Electricity cost of a run, photon output from fixture efficacy, and yield per watt, area and day.
Fixture & run
From the fixture's spec sheet
Add after harvest for yield metrics and cost per gram
Cost & light
Electricity for the run
58.06
Photon output (PPF)
1,296µmol/s
Average PPFD, best case
872µmol/m²/s
Energy per mole of light
102.9Wh/mol
Yield metrics
Enter a dry yield above to compare this run.
How this is calculated
Running cost
kWh = W × h/day × days / 1000; cost = kWh × price
Photon budget
PPF (µmol/s) = W × µmol/J; avg PPFD ≤ PPF ÷ canopy m²; DLI = PPFD × h × 0.0036
- Average PPFD is an upper bound: it assumes every photon lands on the canopy. Wall and edge losses typically remove a further share.
Yield metrics
g/W = dry g ÷ light watts; g/m² = dry g ÷ (ft² × 0.0929)
- Use wall-draw watts, not the fixture's marketing equivalent.
Cited targets
From the genetics.guru grow library, in the units each source used. Grades: strong and moderate are peer-reviewed; community practice is untested.
fixture photon efficacyany2.5–3.4 µmol/JStrong
Tested LEDs ~2.55-3.0; physics limit with 2020 LEDs ~3.4 (white+red), 4.1 (blue+red). DE HPS 1.72.
2 sources
- Kusuma P, Pattison PM, Bugbee B (2020-12). From physics to fixtures to food: current and potential LED efficacy — Horticulture Research 7(1):56
- Westmoreland FM, Kusuma P, Bugbee B (2021-03-23). Cannabis lighting: Decreasing blue photon fraction increases yield but efficacy is more important for cost effective production of cannabinoids — PLOS ONE 16(3):e0248988
benchmark dry inflorescence yield (research chambers)harvest500–750 g/m² per harvestModerate
750-900 umol, 1000 ppm CO2, CBD-dominant cultivar.
1 source
benchmark dry inflorescence yield (median Dutch illicit room model)harvest505 g/m² per harvestModerate
15 plants/m2, 510 W/m2 HPS, 33.7 g/plant.
1 source
yield per installed watt (HPS)harvest0.9–1.6 g/WModerate
Highest at lowest power density; caveat metric (ignores efficacy, rewards under-lighting).
1 source