Hoop House Calculator
Find the hoops, spacing and plastic sheeting needed for a hoop house, from its size.
Reviewed by the ToolNestr Editorial Team — July 2026
How the hoop house calculator works
A hoop house is a series of arched hoops running along a tunnel's length, spaced evenly and covered in plastic sheeting. Sizing the hoops is a straightforward spacing problem: divide the tunnel length by your chosen on-center spacing, round up to get the number of gaps, then add one hoop for the starting end — the same logic used for fence posts or wall studs.
Hoop spacing is a tradeoff between material cost and structural strength. Tighter spacing, around 2 feet on center, holds up better under snow load or wind and suits colder or exposed sites; wider spacing up to 4 feet on center uses less pipe and is common for small DIY tunnels in milder climates. The pipe itself is usually 3/4 to 1-inch EMT conduit or PVC for home-scale hoop houses, bent to an arch matching the tunnel's width and desired peak height.
To estimate the plastic sheeting, the calculator approximates each hoop's arc as a semicircle spanning the tunnel width, giving an arc width per hoop. Multiplying that arc width by the tunnel length gives the sheeting area needed to drape over the frame, with the actual roll length depending on the sheeting's width and how much extra you leave at the base to secure and bury the edges. Peak height mainly affects how much pipe to bend into each hoop, not the sheeting area in this simplified estimate.
Hoop spacing and tunnel sizing guidance follow university extension publications on low-cost high tunnel construction (e.g. Penn State Extension and USDA NRCS high tunnel resources).
Plan the tunnel
Length, width, and peak height.
Choose hoop spacing
Tighter for strength, wider to save material.
Order materials
Hoop count and plastic sheeting area.
The formula explained
Hoop count
= ceil(length ÷ spacing) + 1. A 20 ft tunnel at 4 ft spacing: ceil(20÷4) + 1 = 6 hoops.
Arc width (semicircle estimate)
≈ π × (width⁄2). A 10 ft wide tunnel: π × 5 = 15.7 ft of arc.
Sheeting area
= arc width × tunnel length = 15.7 × 20 = 314 ft².
Worked example
A 30 ft × 12 ft tunnel, 7 ft peak, hoops at 3 ft on-center.
Where hoop houses get used
Backyard season extension
Small home gardeners use a compact hoop house to extend the growing season into fall and get a head start in spring, protecting cold-sensitive seedlings from frost.
Market garden high tunnels
Small commercial growers use larger, taller hoop houses (often called high tunnels) to grow tomatoes, greens, and other crops in-ground under plastic, boosting yields well beyond what field growing allows.
Livestock shelter
The same hoop-and-sheeting structure, often left uncovered on the ends for ventilation, is used as low-cost shelter for goats, chickens, or other livestock in a barnyard.
Overwintering and cold frames
Gardeners in colder climates use a low, tight-spaced hoop tunnel to overwinter perennials or protect a raised bed from snow load through the winter months.
Real-world context
A backyard hoop house 12 ft long and 8 ft wide, with hoops set 3 ft on center, needs 5 hoops and covers 96 square feet of growing area. The semicircle arc estimate over the 8-foot width comes to 12.57 feet, so the plastic sheeting needed is about 151 square feet — small enough to cut from a single roll of standard 6-mil greenhouse film with margin left over to bury the edges.
A market-garden-scale high tunnel, 48 ft long by 14 ft wide with hoops at 4 ft on center, needs 13 hoops and covers 672 square feet of growing beds. Its sheeting requirement — arc width of about 21.99 feet times the 48-foot length — comes to roughly 1,056 square feet, illustrating why commercial growers order greenhouse film in bulk rolls rather than off-the-shelf plastic sheeting.
At the small end, an 8 ft by 6 ft tunnel with tight 2 ft hoop spacing (appropriate for a snowier climate) needs 5 hoops and covers only 48 square feet, with about 75.4 square feet of sheeting required. Tight spacing on a small structure like this uses proportionally more pipe per square foot of growing space than a large tunnel — the tradeoff for a sturdier, snow-load-rated build on a small footprint.
Common misconceptions
"A hoop house and a greenhouse are the same thing." They're related but distinct. A hoop house is typically an unheated, simply-framed structure covered in a single or double layer of plastic film, while a greenhouse usually implies rigid glazing (glass or polycarbonate) and often includes heating and more permanent construction. Hoop houses are the lower-cost, faster-to-build option.
"Wider hoop spacing always saves money without downsides." It's a real structural tradeoff. Spacing hoops farther apart uses less pipe, but it also reduces the structure's ability to shed snow load and resist wind, and a hoop house that collapses under snow can destroy an entire season's crop — tight spacing is worth the extra material cost in exposed or snowy sites.
Related calculators
Frequently asked questions
How many hoops do I need for a hoop house?
Divide the tunnel length by your chosen hoop spacing (commonly 2 to 4 feet on center) and round up, then add one for the starting end. A 20-foot-long tunnel with hoops every 4 feet needs 20 ÷ 4 = 5 gaps, so 6 hoops.
What hoop spacing should I use?
Closer spacing, around 2 feet on center, gives a stronger structure for snow or wind load; wider spacing, up to 4 feet, uses less material but is less sturdy. Most small DIY hoop houses use 3 to 4 feet on center in mild climates.
How much plastic sheeting do I need to cover a hoop house?
The sheeting needs to run the full length of the tunnel and wrap over the arc of each hoop. This calculator approximates that arc as a semicircle spanning the tunnel width, then multiplies by the tunnel length — buy a bit extra beyond this estimate to secure and bury the edges at the base.
What size pipe is typically used for hoop house hoops?
Common DIY hoop houses use 3/4 to 1-inch EMT electrical conduit or PVC pipe bent into an arch, sized to the hoop house width and desired height. Larger commercial high tunnels use heavier galvanized steel tubing.
Sources & references
This tool uses standard formulas and reference values from:
- • American Concrete Institute — ACI 318, Building Code Requirements for Structural Concrete. concrete.org
- • ICC — International Residential Code (IRC), span, footing and framing tables. codes.iccsafe.org
- • APA – The Engineered Wood Association, allowable span and load guidance.
Estimates for planning only. Span, load and code values vary by jurisdiction — verify against your local adopted code and a licensed engineer before building.