Greenhouse Area Calculator

Sizing Your Greenhouse

• Always build bigger than you initially think you need – most gardeners wish they had more space
• Consider pathways (typically 2-3 feet wide) in your layout planning
• Plan for work areas, storage space, and possibly seating
• Standard bench width is 2-3 feet for easy reach
• Minimum recommended size for a hobby greenhouse is 6′ x 8′

Site Selection

• Choose a level site with good drainage
• Position for maximum winter sunlight (south or southeast exposure in northern hemisphere)
• Consider protection from harsh winds
• Ensure accessibility to water and electricity
• Avoid locations under trees that drop branches or heavy shade

Surface Area Calculations

Gable Frame:

• End wall area = Width × Sidewall Height + (Width × (Ridge Height – Sidewall Height))/2 × 2
• Side wall area = Length × Sidewall Height × 2
• Roof area = Length × √((Width/2)² + (Ridge Height – Sidewall Height)²) × 2
• Total Surface Area = End wall area + Side wall area + Roof area

Hoop Frame:

• End wall area = (π × Width × Height)/4 × 2
• Curved surface area = π × Width × Length/2
• Total Surface Area = End wall area + Curved surface area

Volume & Heating Calculations

Volume Estimation:

• Gable: Length × Width × (Sidewall Height + (Ridge Height – Sidewall Height)/2)
• Hoop: Length × (π × Width × Height/4)
• Lean-to: Length × Width × (Sidewall Height + Attachment Height)/2

Heating Requirement Estimation:

Basic formula: BTU/hr = Volume × Temperature Differential × Insulation Factor

• Temperature Differential = Inside Target Temp – Outside Minimum Temp
• Insulation Factor varies by covering material (0.5-1.5)
• Add 10% for each 10 mph of wind speed
• Add 25% safety factor for extreme conditions