Cannabis Yield Calculator
Use this calculator to estimate your total cannabis yield, expected costs, and productivity metrics. Adjust inputs for more accurate results.
Grow Details
Choose how you're growing: indoor for controlled environments, outdoor for natural sun, or hydroponic for water-based systems.
Enter the number of cannabis plants in your grow setup.
Auto-flowering strains are faster; feminized produce only female plants; regular may include males.
Enter total wattage of grow lights in your setup. Used to estimate efficiency.
Number of weeks your plants will be growing before harvest.
Choose training techniques to improve yields by maximizing light exposure.
Estimate how much each plant will produce, on average. Common indoor range: 30–100g.
Note: Results are approximate and vary based on environmental factors, grower experience, and strain specifics.
Updated On: May 13, 2025
Cannabis Yield Calculator
Created by James S. Lockwood
With a background in botany and ecological sciences, James specializes in creating practical tools and resources to help gardeners, farmers, and plant enthusiasts optimize their green spaces.
Trying to estimate how much cannabis you’ll actually get at harvest time? You’re not alone. Growers—both seasoned and new—often find themselves asking: How much weed do you get from a plant? And the truth is, the answer isn’t always straightforward. That’s where a Cannabis Yield Calculator becomes incredibly useful.
This tool helps you predict how much marijuana your grow might produce based on a number of variables—like light, strain, plant count, and growing method. It won’t promise exact results, but it gives you a solid, data-backed estimate. Let’s explore the variables that go into the calculator and how they affect your results.
Table of Contents
How to Calculate Cannabis Yield?
At the heart of it all is the Cannabis Yield Calculator. The calculator uses several key variables:
🌱 1. Number of Plants
More plants can mean more yield—but only if space and light aren’t compromised. Some growers pack 10 plants in a small grow tent, others grow 1 massive plant with training. The calculator adjusts your estimated yield based on the number of plants you enter, but assumes reasonable spacing (use the [Plant Spacing Calculator] if you’re unsure).
💡 2. Grow Type (Indoor / Outdoor / Greenhouse)
Each environment affects yield differently:
Indoor grows are precise but usually limited in space.
Outdoor plants grow larger but depend on weather.
Greenhouse grows blend both, offering some control with natural light.
This selection helps tailor the expected yield range. Indoor plants yield less per plant on average but can be grown in tighter cycles.
🌿 3. Strain Type (Autoflower, Indica, Sativa, Hybrid)
Not all strains yield equally.
Autoflowers are compact and fast—yielding less (50–150g/plant) but great for quick harvests.
Indicas are bushier and usually higher-yielding indoors.
Sativas are tall and airy—great for outdoor space, often yielding more over a longer time.
Hybrids fall somewhere in between, depending on genetics.
Strain type dramatically changes the yield per plant. The calculator adjusts yield ranges accordingly.
🔦 4. Light Wattage (Actual Draw)
This field is crucial for indoor growers.
A 600W light can produce far more than a 150W unit—if all other conditions are ideal. Generally:
0.5 grams per watt = average
1 gram per watt = very good
1.5+ grams per watt = expert
The calculator multiplies your light wattage by an estimated efficiency to calculate grams per watt.
📏 5. Grams Per Watt (User Input or Auto-Suggested)
Here you can enter your own expectation (e.g., 0.8g/watt) or use the calculator’s suggestion based on experience level. It allows flexibility and realism.
Beginners might use 0.5g/watt, while experienced growers with CO₂ enrichment or dialed-in SCROG setups might hit 1.2g/watt or more.
🕐 6. Grow Time (Weeks)
Longer veg = larger plants, but more time between harvests. The grow time lets the calculator adjust for:
Fast autoflowers (8–10 weeks)
Standard photoperiods (12–16 weeks)
It also considers whether you’re doing perpetual grows or one-off cycles.
🧪 7. Training Method Used (Optional)
None: Standard vertical growth.
Topping: Encourages bushy plants, more colas.
LST (Low Stress Training): Bends branches for better light exposure.
SCROG (Screen of Green): High-efficiency technique with even canopy.
Each method affects the plant’s structure and yield potential. The calculator estimates a slight boost (5–25%) depending on method.
🧮 Outputs You’ll Get
Once you enter your data, the calculator provides:
Total yield (grams and ounces)
Yield per plant
Yield per watt
Yield per square foot (estimated)
Cost efficiency if energy cost is added (future option)
It’s a practical tool to align your grow goals with realistic expectations. External guide on cannabis life cycle and yield projections
What is a good yield of cannabis?
A good cannabis yield varies by growing method and experience level. On average:
Indoor growers can expect 100–300 grams (3.5–10.5 oz) per plant.
Outdoor growers may achieve 400–1000+ grams (14–35 oz) per plant.
Yield depends on factors like genetics, lighting, nutrients, training techniques, and grower skill. For hobby growers, anything above 200 grams per plant indoors is often considered a good result. Outdoors, surpassing 500 grams is seen as a strong yield.
Pro Tip: Focus on optimizing plant health and canopy management rather than chasing weight alone.
Looking to fine-tune more than just yield? Try our Grow Room Calculator Suite to optimize lighting, ventilation, CO₂ levels, costs, and more.
Autoflower
50–150g per plant
Fast but small yield — ideal for quick harvests and stealth grows.
Indica
150–400g per plant
Compact and bushy — works well in controlled indoor setups.
Sativa
250–600g per plant
High potential yield but needs more space, light, and time.
Hybrid
100–500g per plant
Results vary — depends heavily on dominant genetics.
Yield Per Plant vs Yield Per Watt
This is a classic debate in grow forums. Some swear by measuring yield per plant—especially in low-plant setups. Others argue grams per watt is more accurate because it reflects efficiency, not just bulk.
Our advice? Use both.
Got a 600W LED and 4 plants? Use both metrics to see how efficient each plant is.
Yielding 500g? That’s ~0.83g/watt—not bad, but room to improve.
Only got 2 plants in a 3×3 tent? Your per-plant yield might be higher, but less efficient.
Indoor vs Outdoor Cannabis Yields
Indoor Yields
📏 1–5 oz per plant
💡 0.5–1.2 grams per watt
🏠 Controlled environment = consistency
Outdoor Yields
🌿 4–35 oz per plant (yes, really)
🌤 More variables = less predictability
⛅ Weather, pests, sunlight duration matter more than light wattage
What is the maximum yield per plant of cannabis?
Under ideal conditions, the maximum yield per cannabis plant can reach:
Indoor (SCROG method): Up to 600–800 grams per plant.
Outdoor (large photoperiod plants): 1000–2000+ grams per plant.
These figures are achieved with expert-level care, optimized environments, high-yielding strains, and extended vegetative periods.
Important: Most growers won’t hit these numbers consistently. They represent peak potential, not typical outcomes.
How big should a 3 week old cannabis plant be?
At 3 weeks old (seedling to early veg stage), a healthy cannabis plant should typically be:
6–10 inches (15–25 cm) tall.
Sporting 3–5 leaf nodes (sets of leaves).
Showing vibrant green color and compact, bushy growth.
Size can vary based on strain, light intensity, and environmental factors. Some slow-growing strains may appear smaller, while vigorous hybrids can be slightly larger.
Tip: Focus on healthy leaf development and root growth rather than height alone at this stage.
How does soil pH affect cannabis yields?
Soil pH plays a crucial role in cannabis growth and yield potential. It affects how well plants absorb essential nutrients like nitrogen, phosphorus, potassium, and micronutrients.
Ideal Soil pH for Cannabis:
Optimal Range: 6.0 to 6.8 for soil-grown cannabis.
Hydroponics/Soilless Mix: Slightly lower, around 5.8 to 6.3.
If the pH is too high (alkaline) or too low (acidic), nutrient uptake is blocked, leading to deficiencies, stunted growth, and reduced yields.
Signs of Soil pH Problems:
Yellowing leaves (chlorosis)
Brown leaf spots
Poor bud development
Slow overall growth
Tip: Regular soil pH testing and adjustments are essential to maintain nutrient availability and maximize cannabis yields.
Use this Soil pH Calculator to check and adjust your growing medium accurately
How to Adjust Soil pH for Better Cannabis Yields?
To Lower Soil pH (More Acidic):
Apply elemental sulfur for gradual pH reduction.
Mix in peat moss or acidic compost.
Use pH-lowered water (adjusted with citric acid or pH down solutions).
To Raise Soil pH (Less Acidic):
Add agricultural lime (dolomite lime).
Use wood ash in moderation.
Incorporate crushed oyster shells for calcium and pH balancing.
Pro Tip: Adjust soil pH slowly over time—sudden changes can stress plants and harm root health.
Learn how soil pH directly affects cannabis yields and how to optimize it
Factors That Affect Cannabis Yields
Even the best calculator won’t save you from poor conditions. Common yield-altering factors include:
Incorrect nutrient ratios (use our [NPK Fertilizer Calculator] to avoid this)
Over/underwatering
Wrong light spectrum or distance
Poor training or none at all
Inadequate air circulation
Rootbound pots
Even experience level matters. The same equipment in the hands of an experienced grower might yield 40% more than a beginner using guesswork.
What cannabis has the highest yield?
Some of the highest-yielding cannabis strains include:
Big Bud: Known for massive flower production.
Critical Mass: Heavy yields with dense, resinous buds.
Super Skunk: Reliable, high-yielding hybrid.
Amnesia Haze: High outdoor yield potential with proper care.
Blue Dream: Balanced growth and generous harvests.
Yields vary by growing conditions, but these strains are favored for their consistent heavy harvests.
Note: Choosing a high-yield strain is important, but maximizing yield also depends on grow techniques like SCROG, LST, and optimal nutrient management.
What are the best tips to maximize cannabis yields?
To maximize cannabis yields, focus on optimizing these key areas:
1. Choose High-Yielding Strains
Start with genetics known for large harvests like Big Bud, Critical Mass, or Blue Dream.
Autoflowers yield less than photoperiod plants, so select accordingly.
2. Provide Optimal Lighting
Use high-intensity LED or HPS lights for indoor grows.
Ensure proper light distance and coverage for even canopy growth.
3. Master Training Techniques
Techniques like Low-Stress Training (LST), Screen of Green (SCROG), and topping promote more bud sites.
Spreading the canopy increases light penetration and yield.
4. Dial in Nutrients & Watering
Follow a balanced nutrient schedule for each growth stage.
Avoid overwatering—good root aeration is crucial for plant health.
5. Control Environment Conditions
Maintain temperature (70–85°F) and humidity (40–60%).
Ensure proper air circulation and CO2 enrichment for vigorous growth.
6. Extend Vegetative Period (for Photoperiods)
Allow plants to grow larger before flipping to flower for bigger potential yields.
Larger plants = more bud sites.
7. Harvest at the Right Time
Harvesting too early reduces yield and potency.
Wait for optimal trichome development and bud maturity.
Pro Tip: Healthy plants = Higher yields. Stress-free growth cycles are more productive than chasing aggressive techniques too soon.
Cannabis Yield Calculator FAQs
Q: How much weed does one plant produce?
A: Indoor: 100–300g. Outdoor: 400–1000g+. Strain and environment matter.
Q: How do I know my grams per watt?
A: Take your dry yield (in grams) and divide it by your actual light wattage.
Q: Can I improve yield without changing my setup?
A: Yes. Better training, spacing, and nutrients can all boost yield.
Q: Should I top or scrog?
A: If you’ve got time and patience—yes. SCROG especially boosts yield in small spaces.
Cannabis Growing Tools & Resources
Pair this Cannabis Yield Calculator with the following tools for even better results:
Plant Spacing Calculator – Avoid overcrowding, improve light penetration.
NPK Fertilizer Calculator – Dial in nutrients without guesswork.
With the right tools, even small home grows can become reliable and rewarding.
Disclaimer
This Cannabis Yield Calculator is intended for informational and educational purposes only. The results are estimates based on user-provided inputs and generalized data. Actual cannabis yields can vary significantly due to factors such as genetics, environment, grow techniques, equipment quality, and user experience.
We do not guarantee specific results or outcomes. Always comply with your local laws and regulations regarding cannabis cultivation. This tool is not intended to encourage or promote illegal activity in any jurisdiction.