Estimate your cannabis harvest in seconds. Set your grow space, LED wattage, plant count, grow medium and experience level to get a yield range in grams and ounces, the optimal number of plants, cycle time and estimated monthly electricity cost. This cannabis grow calculator also covers harvest timing through the harvest calculator and running costs through the grow room cost calculator.
The estimate starts from grams per watt, the measure growers actually compare. A baseline of 0.75 g/W is adjusted three ways. Experience: a first grow lands near 0.4 g/W, an intermediate grower around 0.6 g/W, and an expert dialling in VPD, feeding and training can reach 0.8 g/W or better. Light density: below 25W per square foot yields fall off sharply, 30–50W per square foot is the efficient band, and pushing past 65W adds heat and stress faster than it adds weight. Plant density: roughly one plant per 4 square feet is the target, and going far under or far over that costs yield. The result is shown as a range, because strain and technique move the same setup by 20% in either direction.
A 2x2 tent (4 sq ft) under 150W with 1 plant averages about 90g (3 oz) per harvest — roughly 90g per plant, 0.60g per watt, and 23g per square foot. A 2x4 tent (8 sq ft) under 250W with 2 plants averages about 150g (5 oz) per harvest — roughly 75g per plant, 0.60g per watt, and 19g per square foot. A 3x3 tent (9 sq ft) under 300W with 2 plants averages about 180g (6 oz) per harvest — roughly 90g per plant, 0.60g per watt, and 20g per square foot. A 4x4 tent (16 sq ft) under 500W with 4 plants averages about 300g (11 oz) per harvest — roughly 75g per plant, 0.60g per watt, and 19g per square foot. A 4x8 tent (32 sq ft) under 1000W with 6 plants averages about 540g (19 oz) per harvest — roughly 90g per plant, 0.54g per watt, and 17g per square foot.
Yield per plant is the figure most growers want and the least reliable one: four plants in a 4x4 tent under the same light produce roughly the same total as one well-trained plant, so per-plant weight mostly reflects how many plants share the space. Grams per watt is the honest comparison between setups, and grams per square foot tells you whether your light is the limit or your space is.
For an intermediate grower in coco coir: 2x2 grow tent yield: 72–108g (3–4 oz) per harvest from 4 sq ft under a 150W LED, about 1-2 plants. 2x4 grow tent yield: 120–180g (4–6 oz) per harvest from 8 sq ft under a 250W LED, about 1-4 plants. 3x3 grow tent yield: 144–216g (5–8 oz) per harvest from 9 sq ft under a 300W LED, about 1-5 plants. 4x4 grow tent yield: 240–360g (8–13 oz) per harvest from 16 sq ft under a 500W LED, about 2-8 plants. 4x8 grow tent yield: 432–648g (15–23 oz) per harvest from 32 sq ft under a 1000W LED, about 5-16 plants. 5x5 grow tent yield: 384–576g (14–20 oz) per harvest from 25 sq ft under a 800W LED, about 4-13 plants. 5x10 grow tent yield: 648–972g (23–34 oz) per harvest from 50 sq ft under a 1500W LED, about 8-25 plants. 8x8 grow tent yield: 864–1296g (30–46 oz) per harvest from 64 sq ft under a 2000W LED, about 10-32 plants. 10x10 grow tent yield: 1296–1944g (46–69 oz) per harvest from 100 sq ft under a 3000W LED, about 16-50 plants. Choosing the tent itself is covered in our best grow tents guide.
Yield per plant depends on grow space, light wattage, medium, and strain. A 4x4 tent under 400W LED averages 1.5–3 oz per plant in soil, or 2–4 oz in coco. Use the calculator to estimate your exact setup.
A yield calculator gives a realistic range based on grams-per-watt, light efficiency, and plant density. Actual results vary with strain, training, and environment, but the estimate is a reliable planning baseline.
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