Yield Estimator & Production Planner

Grow Room Yield Estimator & Production Planner

Estimate your harvest weight from watts, light type, and grow modifiers — then see your full Veg → Flower → Dry → Cure timeline at a glance. Need help choosing lights? Talk to a Grow Expert.

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Yield Estimator & Production Planner

Enter your lights and grow details. Switch to Advanced to add CO₂, training, and experience modifiers.

Lighting Setup

Grow Schedule

How to use this calculator
  1. Enter total true watts of your grow lights — use wall-draw, not "equivalent" wattage.
  2. Select your light type — LED, HPS/MH, or CMH. Each has a different efficiency baseline.
  3. Choose your strain type — Indica, Sativa, Hybrid, or Autoflower affects yield modifier and bloom length.
  4. Set your veg and flower weeks — longer veg generally means bigger plants and higher yields.
  5. Advanced mode: add CO₂ enrichment, training technique, and experience level for a refined estimate.
  6. Click Estimate Yield — your harvest weight, g/W efficiency, and full grow timeline appear. Open the Production Timeline to see your Gantt chart.

Formula: Base yield = watts × g/W baseline × strain modifier × CO₂ modifier × training modifier × experience modifier

g/W baselines: LED 1.1 · HPS/MH 0.8 · CMH 0.9 · (all for intermediate grower, no modifiers)

Grow Room Yield Quick Reference — g/W by Light Type, Stage Duration, and Modifier
Light Type Baseline (g/W) Typical Veg Typical Flower Total Cycle 600W Estimate
LED (premium) 1.0–1.5 g/W 4–8 weeks 8–12 weeks 12–20 weeks 600–900 g
HPS / MH 0.7–1.0 g/W 4–8 weeks 8–11 weeks 12–19 weeks 420–600 g
CMH / LEC 0.8–1.1 g/W 4–8 weeks 8–11 weeks 12–19 weeks 480–660 g
Autoflower (LED) 0.7–1.0 g/W 0 weeks 7–10 weeks 9–12 weeks 420–600 g
+CO₂ enriched +20–30% above baseline — — — +120–180 g
+HST training +20–25% above baseline +1–2 weeks — — +100–150 g

Frequently Asked Questions

How much yield can I expect per watt of grow light?
A common benchmark for LED grow lights is 1.0–1.5 grams per watt (g/W) under optimized conditions. Beginners often achieve 0.5–0.8 g/W, while experienced growers with dialed-in VPD, CO₂ enrichment, and canopy training can reach 1.5+ g/W. This calculator uses 1.1 g/W as a conservative LED baseline, which reflects realistic intermediate-level results.

How long does a full grow cycle take from seed to harvest?
A typical indoor photoperiod cycle takes 12–20 weeks total: 4–8 weeks vegetative, 8–12 weeks flowering (strain-dependent), plus 7–14 days drying and 14–28 days curing. Autoflowers finish faster at 8–10 weeks total from seed to harvest. The Production Timeline chart in this tool shows your full calendar visually.

Does CO₂ enrichment really increase yield?
Yes — supplemental CO₂ at 1,200–1,500 ppm can increase yields by 20–30% compared to ambient CO₂ levels (~400 ppm), provided other factors like light intensity, temperature, and nutrients are also optimized. Below 800 ppm enrichment, additional CO₂ has minimal effect. Plants can't use more CO₂ than their light and nutrient levels allow.

What training techniques produce the highest yield?
High-Stress Training (HST) techniques like topping, FIMing, and mainlining can increase yields 20–40% by creating multiple equal colas instead of one dominant main cola. Low-Stress Training (LST) and SCROG (Screen of Green) produce an even canopy for consistent PPFD across all bud sites. Both approaches add 1–2 weeks to vegetative time but pay off significantly at harvest.

Why is my actual yield lower than the calculator estimate?
Common reasons: suboptimal VPD or humidity, insufficient light intensity (PPFD below 600–800 µmol/m²/s), nutrient deficiencies or lockout, light burn, root problems, or harvesting too early before trichomes are fully mature. The calculator estimates maximum potential — real-world yields typically land at 60–90% of that figure for most growers. Use Advanced mode with the Beginner experience modifier for a more conservative estimate.
📅 Production Timeline — Full Grow Calendar Timeline ▾
Vegetative
Flowering
Drying
Curing
Harvest / Ready

Timeline updates live when you change inputs and click Estimate Yield. Hover or tap a phase bar to see exact dates. Calculate your yield above to populate the chart.

Ready to maximize your harvest?

Shop premium LED grow lights rated up to 2.8 µmol/J efficacy from top brands like Spider Farmer, Mars Hydro, and HLG.
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