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How Efficient Is Your Grow?

Compare one harvest across four useful operating ratios. The bands are transparent reference points, not universal biological targets, and the dollar output is a directional gross-revenue scenario.

🌱 Your Last Harvest
Number of Lights ?Count all flowering fixtures in this room. If wattages differ, calculate the weighted-average wall draw per fixture and enter it as Custom below. In the harvested room
Fixture Wattage ?Enter average actual wall draw per flowering fixture at the intensity used for this harvest. Use a measured or verified value when possible. Average wall draw per light
Dry Yield ?Total final dry, trimmed, saleable flower weight from this room's last harvest. Do not substitute wet or pre-trim weight. Pounds harvested (dried, trimmed)
Flowering Canopy ?The actual plant canopy footprint, not the total room square footage. If your room is 400 sqft but walkways, aisles, and equipment take up half the space, your canopy is ~200 sqft. Square feet of canopy in the room
Flower Days ?Count from the day you switch to the flowering light schedule to the day you chop. Use the actual duration for the harvested run. Flip to chop
Turnaround Days ?Days between chopping one run and flipping the next in the same room. Includes cleanup, sanitization, transplanting, and any veg time in the flower room before flip. Chop to next flip (same room)
Flower Rooms ?How many separate flower rooms do you run? This scales your dollar impact to the full facility. If you run one room, leave it at 1. If all rooms are similar in size and setup, the math scales linearly. Total active flower rooms in your facility
Wholesale Price ?Your average net price per pound after broker fees or volume discounts. It is used only for gross-revenue scenarios and does not affect the reference-band ratings. $/lb (for dollar impact estimates)
$
Reference bands are informed by the linked survey, research, and industry guidance, then applied as planning heuristics. See the evidence and limits.
🌿 Grams per Square Foot -
- g/sqft
0355580130+
Reference context: CBT/Fluence 2025 (76 responses in the reported yield base)
💡 Yield per Light -
- lb/light
01.52.53.04.5+
Industry context: CBT (Lange, 2019); bands are planning heuristics
Grams per Watt -
- g/W
00.81.21.83.0+
Lighting context: Rodriguez-Morrison et al., 2021; the g/W bands themselves are planning heuristics
🔄 Harvests per Room per Year -
- turns/year
24.05.05.87.0+
Industry context: Pipp Horticulture, 2023; actual turns depend on cultivar and room workflow

Enter your numbers to see your scorecard

Your reference-band comparison and directional scenarios will appear here.

A reference band points to a question. The operational record gives your team the context to investigate it.
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See the throughput workflow

A turns-per-year ratio starts with the crop calendar and the work between harvests.

This walkthrough shows how Growgoyle schedules crew work on the living crop calendar. It demonstrates the operational workflow behind timing; it does not prove that a particular reference band is attainable for your rooms.

Schedule a Week of Cultivation Work in Seconds

Put crop-linked defoliation, scouting, and canopy-photo work into a crew-ready weekly plan.

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Reference Context and Limits

The sources below provide context. The colored thresholds are Growgoyle planning heuristics, not validated universal performance standards.

Industry Survey

CBT / Fluence Lighting

10th Annual State of the Lighting Market Report (2025). The report received 185 total responses; the commercial yield distribution cited here uses a smaller base of 76 respondents. It informs g/sqft context only.

View report (PDF) →
Peer Reviewed

Rodriguez-Morrison et al., 2021

University of Guelph research on cannabis yield response to light intensity. It provides lighting context but does not validate this page's commercial g/W tier cutoffs.

View study (PMC) →
Expert

Ryan Douglas, Greenhouse Grower

25 years in commercial horticulture. Start-ups: ~35 g/sqft. Established: 50-70 g/sqft. 100+ g/sqft: few and far between.

Read article →
Expert

Pipp Horticulture, 2023

Industry guidance on room turnaround and annual harvest cadence. Use it as workflow context; cultivar length, sanitation, staffing, and facility design change the attainable number.

Read article →

Frequently Asked Questions

Why these 4 metrics and not others?
These four ratios are easy to calculate from records many facilities already have: canopy area, fixtures, wattage, dry yield, and cycle time. They offer different views of the same operation, but they are not independent. The three yield ratios share the same yield numerator, so use them together as comparison prompts rather than four separate proofs.
Why is my grams per watt different from grams per square foot?
They use different denominators. Grams per square foot divides final dry flower by canopy area. This page's grams per watt divides the same flower weight by entered fixture wall draw. It is a harvest-output-to-installed-lighting-power ratio, not total electrical efficiency: it does not include photoperiod, cycle length, dimming history, HVAC, dehumidification, or other facility loads.
How accurate are these benchmarks?
Treat them as reference bands, not promises or biological targets. The CBT/Fluence report provides survey context for g/sqft, with 76 responses in the reported yield base. The lighting study and industry articles provide additional context, but they do not validate every cutoff on this page. Compare your own facility using consistent definitions.
What should I optimize first?
The tool highlights the lowest reference band, not the easiest fix or the largest proven financial opportunity. Start by checking data quality and operational constraints, then test a plausible change against your own cost, quality, labor, energy, and crop-risk records.
Does this tool track my data?
The calculations run in your browser, and the fields are saved in browser local storage so they can persist when you return. The scorecard does not make a calculation API request. Standard public-page usage analytics still apply as described in the privacy policy.

Grow Room Efficiency: What the Data Shows

Grow room efficiency is not one number. These four ratios offer compact views of canopy use, fixture output, output per watt of installed lighting, and room cadence. They do not measure quality, saleable-grade mix, labor, HVAC energy, crop risk, or total cost on their own.

The Four Metrics and Why They Matter

Metric What It Measures Upper Reference Band Why It Matters
Grams/sq ft Canopy utilization 80+ g/sqft Are you filling the room?
Lbs/light Fixture performance 3.0+ lb/light How hard is each light working?
Grams/watt Output per installed lighting watt 1.8+ g/W How does harvest weight compare with entered fixture wall draw?
Turns/year Operational throughput 5.8+ per room How fast do rooms cycle?

How These Metrics Interact

The four metrics are not independent. A change in entered harvest weight moves grams per square foot, pounds per light, and grams per watt together because all three reuse the same numerator. Room cadence uses separate timing inputs. If yield and cadence both change, the annual gross-revenue scenario compounds those assumptions.

Because g/sqft, lb/light, and g/W all reuse the same yield numerator, a stronger harvest can move all three at once. Do not add their modeled scenarios together. Use each ratio to ask a different operational question, then verify the answer in the underlying room and batch record.

Common Efficiency Gaps

Useful areas to inspect when a reference ratio is lower than expected include:

Canopy utilization. Empty canopy, uneven plant size, edge losses, cultivar architecture, and saleable-grade mix can all influence grams per square foot. Inspect the room record before assuming canopy management is the cause.

Room turnaround. Cleaning, repairs, plant readiness, staffing, and schedule conflicts can extend chop-to-flip time. Shortening it may increase annual room availability, but sanitation and crop readiness still set the boundary.

Variation between runs. A single harvest can hide normal cultivar differences or an unusual event. Check relative yield variation across several comparable harvests before treating one score as representative.

Using Your Scores

The scorecard highlights the lowest reference band as a place to investigate. It does not know feasibility, crop quality, facility constraints, incremental costs, or causality. Review the source records, choose a plausible operational test, and measure the full result rather than chasing the score by itself.

Read the complete guide to grow room optimization KPIs →

These tools exist because I needed them. I'm Eric, commercial grower and software engineer in Michigan. I built Growgoyle to run my own facility and these calculators are just a piece of it. If you're running a grow and want to talk shop, text me.

Text me: 616-221-9856  ·  info@growgoyle.ai

- Eric