| Shape | Dimensions | Walkway | Fixed | Usable area |
|---|---|---|---|---|
| Rectangle | 12 m × 6 m | 10% | 5% | 61.20 m² |
| Circle | Diameter 8 m | 12% | 6% | 40.22 m² |
| Regular Polygon | 6 sides, 4 m | 8% | 4% | 35.03 m² |
Example values are illustrative for planning and comparisons.
- Rectangle: A = L × W
- Square: A = S²
- Circle: A = π × (D/2)²
- Ellipse: A = π × (a/2) × (b/2)
- Regular polygon: A = (n × s²) / (4 × tan(π/n))
Usable Area = Gross Area × (1 − Deductions)
Deductions = (walkway% + fixed% + obstruction%) / 100. Increase deductions when you need wide aisles or staging zones.
- Select your units and greenhouse shape.
- Enter the footprint dimensions. Use the frame’s inside measurement when possible.
- Set allowances for walkways, fixed equipment, and obstructions.
- Optionally add a waste factor for floor coverings or liners.
- Press Calculate. Download CSV or PDF for your plan.
Floor area is the starting point for bench runs, bed spacing, irrigation zones, and circulation. This calculator converts common footprints into comparable floor area, then applies practical deductions so you can estimate how much space is truly available for crops and workflow. Use the same assumptions across designs to compare options before you buy frames or glazing, with confidence.
Rectangular frames are typical for hoops and rigid panels, making length × width the most common input. Circular and oval footprints appear in specialty domes and compact backyard builds, where wind loads can be smoother. Regular polygons approximate round structures while keeping straight edges for base rails and anchoring. If you already have a plan set, select the closest shape to avoid manual conversions.
Usable growing area depends on how you allocate paths, staging, and fixed equipment. Many growers reserve 8–20% for walkways, then add fixed zones for heaters, tanks, potting, or storage. Obstruction allowance helps account for posts, corner losses, drains, and utility corridors. When labor efficiency matters, slightly higher walkway percentages can reduce bottlenecks and plant damage.
Floor coverings, weed barriers, liners, or insulation panels often require overlap and trimming. The waste factor increases gross area to estimate purchase quantity. When cuts are complex, increase waste; when using roll goods with long runs, reduce waste. A 5–10% buffer is common for sheet goods, while intricate layouts may need more. Use the CSV export to compare scenarios across multiple greenhouse sizes and suppliers.
Perimeter supports planning for curbs, baseboards, edging, and drainage channels around the footprint. It also helps estimate sealing tape, perimeter insulation, or pest barriers installed at the base. Perimeter is provided for geometric shapes, while custom-area entries focus on area-only planning. Switch between meters and feet to match vendor spec sheets and keep takeoffs consistent.
1) Should I measure inside-to-inside or outside-to-outside?
Use inside-to-inside for growing and flooring plans. Use outside-to-outside when estimating site clearance, base framing, or ground preparation around the structure.
2) What walkway percentage is typical for benches?
For bench rows, 10–18% often works. Increase the percentage when using carts, harvest bins, or wider turning radii at the ends of aisles.
3) Why does usable area differ from gross area?
Usable area subtracts allowances for walkways, fixed zones, and obstructions. It approximates space available for beds, benches, and crop movement rather than total footprint.
4) When should I use the waste factor?
Use it when ordering floor coverings, liners, or barrier cloth. Overlap, seams, and trimming create offcuts, so a modest waste percentage improves purchasing accuracy.
5) Can I use this for irregular shapes?
Yes. Choose Custom Area and enter your measured area. You can obtain that value from a site plan, GIS tool, or by splitting the shape into simple sections.
6) Is perimeter useful for rectangle-only builds?
Perimeter helps in any geometric footprint. It supports estimating edging, base rails, drainage runs, and pest barriers that follow the greenhouse boundary.