Hoop House Calculator
The length of each hoop, how many hoops, and the size of plastic sheet for a round-topped hoop house or high tunnel, from its width, height and length.
Result
18.85 ft
Plastic is sold in whole sizes; add an allowance at the sides and ends to fasten it.
- Hoops
- 7
- Total hoop material
- 131.9 ft (1,583.4 in, 40.2 m)
- Plastic sheet width
- 18.85 ft (226.19 in, 5.75 m)
- Plastic sheet length
- 24 ft (288 in, 7.32 m)
- Area of each end wall
- 56.5 ft² (5.3 m²)
https://calcgallery.com/landscaping/hoop-house-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use the Hoop House Calculator
- Enter the width across the base of the arch and how high the arch rises above it, plus any straight sidewalls below the curve.
- Enter the house length and the spacing between hoops.
- Add an allowance at the sides and ends for fastening or burying the plastic, then read the hoop length, hoop count and sheet size.
The arch
radius = (width² ÷ 4 + height²) ÷ (2 × height)arc length = radius × 4 × atan(2 × height ÷ width)hoop = arc length + 2 × sidewall heighthoops = length ÷ spacing, rounded up, + 1Any round-topped arch through the two base points and the peak is part of one circle, and these two formulas give its radius and length from the width and height alone. When the height is half the width the arch is a semicircle, the radius is half the width, and the arc is π times the radius.
End walls
The area of each end is the circular segment under the arch, radius² × (angle − sin angle) ÷ 2, plus the rectangle of any sidewalls. Doors, vents and framing come out of that area and are left to the build.
With your numbers
- Arch radius = (width² ÷ 4 + height²) ÷ (2 × height); arch length = radius × 4 × atan(2 × height ÷ width)
- Hoop = arch + 2 × sidewall; hoops = length ÷ spacing, rounded up, + 1
Quick reference
Plastic is sold in whole sizes; add an allowance at the sides and ends to fasten it.
| Job | Length of each hoop |
|---|---|
| 12 ft wide, 6 ft high, 24 ft long | 18.85 ft |
| 10 ft wide, 4 ft arch on 2 ft sides | 17.83 ft |
| 20 × 48 ft high tunnel | 34 ft |
| 6 ft low tunnel, 3 ft high | 9.42 ft |
| 14 ft wide, 7 ft high, 30 ft long | 21.99 ft |
| 4 m wide, 2 m high, 10 m long | 6.28 m |
Common questions about the Hoop House Calculator
- How many hoops do I need?
- The length divided by the spacing, rounded up, plus one, because there is a hoop at each end. A 24-foot house with hoops every 4 feet has 7. Rounding up keeps the spacing at or under what you entered.
- How long does each hoop need to be?
- As long as the arch plus both sidewalls. A 12-foot-wide semicircular hoop, 6 feet high, is half a circle of 12-foot diameter: π × 12 ÷ 2 = 18.85 feet. A flatter arch is shorter than a semicircle over the same width; the page works it out from the width and height for any round-topped arch.
- What size of plastic do I buy?
- Wide enough to go over the hoop from one side to the other plus what you bury or fasten along each side, and long enough for the house plus what you pull down over each end. Film is sold in set widths and lengths, so choose the next size up. The end walls are usually covered separately.
- Can the arch be taller than half the width?
- Not as a single circular arc: past a semicircle it would bulge wider than its base. Add straight sidewalls below the curve for more headroom, which is how many high tunnels are built. Pointed, gothic arches are a different shape the page does not cover.