Greenhouse Heater Calculator
Formula: (2×Length×Height) + (2×Width×Height) + Roof Area
Formula: ΔT = Desired Temp − Minimum Outdoor Temp
Formula: HeatLoss = TotalSurfaceArea × U-value × ΔT
Formula: HeaterCapacity = HeatLoss ÷ 3412
Formula varies by energy source. For Electric: Cost = (HeaterCapacity × RunHours × EnergyCost) ÷ Efficiency
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.
Looking to optimize your greenhouse heating? Our Greenhouse Heater Calculator is designed to help you determine the right heater size, heat loss, and heating costs efficiently. Whether you’re growing vegetables, flowers, or tropical plants, maintaining the right temperature is crucial for plant health and growth.
This greenhouse heater calculator provides accurate BTU/hr or kW requirements based on your greenhouse size, insulation material, and outdoor conditions. It also estimates your greenhouse heating costs, making it easier to choose an efficient heater that balances performance with energy savings.
Table of Contents
How to Calculate Greenhouse Heating Requirements?
To calculate how much heating your greenhouse needs, you’ll need to know the volume of the space (length × width × height), the desired temperature increase, and the insulation level. Our Greenhouse Heater Calculator automates this using standard formulas for BTU or kilowatt estimates.
What Is a Greenhouse Heater Calculator?
Looking for the right heater for your greenhouse? Our Greenhouse Heater Calculator helps you estimate the heating power (BTU or kW) you need based on your greenhouse size, insulation, and climate. Whether you’re growing tropical plants in winter or just want to protect your seedlings from frost, this tool gives you a fast, accurate estimate.
How Does the Greenhouse Heater Calculator Work?
Our tool takes the following factors into account:
1️⃣ Greenhouse Size & Structure 📏
- Enter your greenhouse length, width, and height (feet or meters).
- Choose your glazing material (Glass, Polycarbonate, Polyethylene) – this affects heat retention.
- Calculates total surface area to determine heat loss.
- Formula Used:
2️⃣ Temperature Maintenance 🌡
- Enter minimum outdoor temperature (coldest winter night).
- Enter desired greenhouse temperature (optimal plant growth temp).
- Calculates temperature difference (ΔT) to determine how much heat is needed.
- Formula Used:
3️⃣ Heat Loss Calculation (BTU/hr or Watts) 🔥
- The calculator estimates heat loss through greenhouse walls, roof, and ventilation.
- Uses heat transfer coefficients (U-values) for materials:
- Glass: 1.0 BTU/hr·ft²·°F
- Polycarbonate: 0.7 BTU/hr·ft²·°F
- Polyethylene Film: 0.5 BTU/hr·ft²·°F
- Formula Used:
4️⃣ Greenhouse Heater Size Calculator (BTU or kW) ⚡
- The calculator recommends heater size based on BTU/hr or kW requirements.
- Converts BTU/hr to kW for electric heaters.
- Formula Used:
5️⃣ Greenhouse Heater Cost Calculator 💰
- Enter your energy source (Electric, Gas, Propane).
- Input run hours per day and local energy cost (e.g., $/kWh, $/gallon).
- Adjust for heater efficiency (e.g., 90%, 80%, etc.).
- Estimates monthly or seasonal heating costs for better budgeting.
- Formula Used:
Why Use Our Greenhouse Heating Calculator?
✅ Accurate Heat Loss Estimation – Get precise BTU/hr or kW calculations based on real-world greenhouse conditions.
✅ Optimize Greenhouse Heating Costs – Reduce energy bills with the right heater size and efficiency.
✅ Prevent Plant Damage – Avoid temperature fluctuations that can harm your crops.
✅ User-Friendly & Free – Instantly calculate heating needs without complicated formulas.
FAQs: Greenhouse Heater Calculator
How do I calculate the BTU needed to heat my greenhouse?
Use this greenhouse heater BTU calculator by entering your greenhouse size, glazing material, and temperature requirements. It will estimate heat loss (BTU/hr) and suggest the correct heater size.
How many kW does a greenhouse heater use?
The heater’s power (kW) depends on your heat loss calculation. The formula used is:
What’s the best greenhouse heating system?
- Electric Heaters – Best for small greenhouses, precise temperature control.
- Gas Heaters (Natural Gas, Propane) – Ideal for large greenhouses, cost-efficient for big operations.
- Solar Greenhouse Heaters – Sustainable but dependent on sun exposure.
How much does it cost to heat a greenhouse?
Use our greenhouse heating cost calculator to estimate costs based on electricity, gas, or propane usage. Input your local energy rates and heater efficiency for accurate cost predictions.
What’s the best greenhouse insulation to reduce heat loss?
- Double-layered Polycarbonate – Reduces heat loss by up to 50%.
- Bubble Wrap Insulation – Budget-friendly insulation for winter.
- Thermal Curtains – Retains warmth during cold nights.
How do I calculate heater size for a greenhouse?
To calculate the heater size, first determine the volume of your greenhouse (length × width × height in feet). Then, decide how many degrees you need to raise the internal temperature compared to the outside. Multiply the volume by a heat loss factor (based on insulation) and the temperature difference. Our Greenhouse Heater Calculator simplifies this process and gives you the required BTU or kW instantly.
What size heater do I need for a 10×20 greenhouse?
For a 10×20 greenhouse with an average height of 8 feet, the volume is 1,600 cubic feet. Depending on your climate and insulation, you might need anywhere from 15,000 to 35,000 BTUs to maintain a stable internal temperature during cold months. Use our calculator to fine-tune the estimate based on your local conditions.
What is the best temperature for a greenhouse in winter?
Most plants thrive in greenhouse winter temperatures between 45°F and 75°F, depending on the crops you’re growing. Cold-tolerant vegetables like lettuce and spinach can survive in the 40s, while tropical or fruiting plants may need it closer to 70–75°F. Keep consistent heat with the right-sized heater to avoid plant stress.
Should I use gas or electric heaters in a greenhouse?
Both gas and electric heaters have pros and cons. Electric heaters are clean, easy to install, and ideal for small to medium greenhouses. Gas heaters (natural gas or propane) are often more economical for larger greenhouses but require proper ventilation to prevent CO₂ buildup. Choose based on your size, budget, and energy availability.
Disclaimer for Greenhouse Heater Calculator
The Greenhouse Heater Calculator provides estimates for heating requirements, heat loss, and energy costs based on user input. These calculations are for informational purposes only and should not be considered exact figures for heating system installation. Actual heating needs may vary due to environmental factors, greenhouse insulation, and heater efficiency. Always consult a professional before purchasing a greenhouse heating system. We are not responsible for any decisions made based on the calculator’s results.
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