Hydroponic System Sizer — Planning Your Grow Capacity

Illustrative reservoir volume and USD budget by system and plant count only; no crop, spacing, area, yield or lighting model.

Planning a new build? The System Sizer provides an illustrative volume and budget comparison. Before you buy your first bucket or LED, you need to know if your goals match your space and budget.

Quick answer

Illustrative reservoir volume and USD budget by system and plant count only; no crop, spacing, area, yield or lighting model. Select DWC, NFT, Kratky or drip and enter a positive whole plant count. Example DWC 10 plants: 5 L/plant gives 50 L; $80 + $12/plant gives $200. These constants are illustrative, not supplier quotes or crop-specific requirements.

How to Use This Calculator

Illustrative reservoir volume and USD budget by system and plant count only; no crop, spacing, area, yield or lighting model. Select DWC, NFT, Kratky or drip and enter a positive whole plant count. Example DWC 10 plants: 5 L/plant gives 50 L; $80 + $12/plant gives $200. These constants are illustrative, not supplier quotes or crop-specific requirements.

Key Planning Metrics

1. Plant Spacing

• Lettuce/Herbs: 6–8 inches (15–20 cm) apart.
• Peppers/Tomatoes: 18–24 inches (45–60 cm) apart.
• Microgreens: 0 inches (full tray coverage).

2. Reservoir "Rule of Thumb"

• Small Plants: 0.5 – 1 Gallon per plant.
• Large Plants: 3 – 5 Gallons per plant. Note: These are minimums. More volume equals more stability.

3. Lighting Density

• Low Light (Greens): 20–30 Watts per square foot.
• High Light (Fruit): 40–60 Watts per square foot. (Assuming modern, high-efficiency LEDs)

The Logic Behind the Numbers

Illustrative reservoir volume and USD budget by system and plant count only; no crop, spacing, area, yield or lighting model. Select DWC, NFT, Kratky or drip and enter a positive whole plant count. Example DWC 10 plants: 5 L/plant gives 50 L; $80 + $12/plant gives $200. These constants are illustrative, not supplier quotes or crop-specific requirements.

Sizing by System Type

Worked Examples

Illustrative reservoir volume and USD budget by system and plant count only; no crop, spacing, area, yield or lighting model. Select DWC, NFT, Kratky or drip and enter a positive whole plant count. Example DWC 10 plants: 5 L/plant gives 50 L; $80 + $12/plant gives $200. These constants are illustrative, not supplier quotes or crop-specific requirements.

Common Sizing Mistakes

• Copying spacing numbers across crop types. Lettuce spacing crammed with tomato plants suffocates roots and blocks light penetration.
• Sizing the reservoir for day-one plants, not mature plants. A seedling drinks almost nothing; a fruiting tomato at week 10 can drink 1+ gallon/day.
• Ignoring walkway and maintenance space in the area calculation, then discovering the system can't actually be reached to harvest.
• Using "equivalent wattage" marketing numbers instead of actual measured draw — see watts per plant for real-world figures.

Why Sizing Matters

Under-sizing your reservoir leads to massive pH and EC swings that can kill plants in 24 hours. Over-crowding your plants leads to poor airflow, which triggers mold, powdery mildew, and Calcium deficiency.

Pro Tip: Leave Room for You

When sizing a system for a room, remember that you need to fit in there too. Leave at least 2 feet (60 cm) of "walking/maintenance" space around your system so you can check the reservoir and harvest without breaking stems.

See Also

• VPD Calculator — Managing the environment in your newly sized space.
• DLI Calculator — Ensuring your lights match your plant count.
• Economics of Home Hydroponics — Does the size of your system save you money?
• Reservoir Sizer — Fine-tune reservoir volume once your plant count is set.
• Dutch Bucket — A common choice for the fruiting-crop densities above.