Hoop House Calculator

Hoop House Calculator for round, gothic, gable or lean-to frames that finds bow length or peak height, roof and endwall film, pipe sticks, headroom width, heater size and fuel use.

How the Hoop House Calculator Sizes Your Hoops

A hoop house calculator starts from three numbers: the width at the ground, the peak height and the length. Those three decide the bow length of every hoop, the plastic you buy, the pipe you cut and the heater you need on the coldest night.

Most online tools stop at surface area and a heater figure built from conduction alone. The hoop house calculator also solves the bow length or the peak height, counts pipe sticks with offcuts shared, sizes the film with flaps, and adds the air leakage that most heater sizing leaves out.

Run the hoop house calculator on its default build and the numbers connect. A 14 ft wide, 32 ft long round hoop house with a 7 ft peak needs 9 hoops at 4 ft spacing, each bow 21 ft 11-7/8 in long, and a 26 × 38 ft roof sheet. It holds 2,463 cu ft of air and needs a 64,723 BTU/h heater to hold 50°F when it is 0°F outside.

Hoop House Height and Bow Length

Bow length is the pipe measured along the curve from one ground post to the other. For a round (Quonset) hoop with no sidewalls, it is half the circumference of an ellipse that is as wide as the house and as tall as the peak.

When the peak is exactly half the width, the ellipse becomes a half circle, and the bow length formula shrinks to one line.

$$B=\frac{\pi \times W}{2}$$

B is the bow length and W is the width at the ground, both in feet. This is the first value any hoop house calculator should solve. A 14 ft wide half circle needs a 21.99 ft bow and peaks at 7 ft. Any other peak height uses the full ellipse arc, which the hoop house calculator solves numerically instead of with a rough shortcut.

Straight sidewalls add their height twice to the bow, once on each side. A 2 ft sidewall on the same 14 ft hoop adds 4 ft of pipe, raises the peak by 2 ft and widens the standing room far more than a taller arch would. The hoop house calculator shows that gain as the width with headroom.

Gothic hoop formula

A gothic (peaked) hoop is two circular arcs that meet at the ridge. Each arc is centered on the ground line, on the far side of the centerline, so the roof sheds snow better than a round top.

$$c=\frac{h^2-a^2}{2a},R=c+a,B=2R\times \arctan \left(\frac{h}{c}\right)$$

Here a is half the width, h is the roof rise above the sidewalls, c is how far each arc center sits past the centerline, and R is the arc radius. The rise must be at least half the width, or the two arcs cannot meet in a point.

A 14 ft wide gothic hoop with a 9 ft peak needs a 24.553 ft bow (24 ft 6-5/8 in). At 6 ft above the floor it is 9.60 ft wide, against only 7.21 ft for the 7 ft round hoop of the same width. That extra 2.4 ft is room for a walkway plus a full bed, so compare both profiles in the hoop house calculator before you buy pipe.

Working backward from a bow

When you already own pipe, the question flips. A hoop house height calculator runs the same arc formulas in reverse, from bow length and width to the peak height the hoop will reach.

A 20 ft bow set 12 ft wide stands 6.72 ft tall at the peak, but it has 6 ft of headroom over just 5.41 ft of the middle. If you need to walk in comfortably, either narrow the hoop or add pipe to the bow and run the hoop house calculator again.

Gable and lean-to frames

Gable and lean-to houses use straight rafters instead of a bent bow. A gable frame is two rafters plus two sidewalls, and a lean-to frame is one rafter plus a front wall, with the back edge fixed to an existing building.

$$B_{gable}=2\sqrt{a^2+h^2}+2s,B_{lean}=\sqrt{W^2+h^2}+s$$

Here a is half the width, h is the roof rise above the walls, s is the sidewall or front wall height and W is the full width. Each B is the pipe length of one frame from the ground, up and over, to the ground or the building.

A 14 ft gable with 5 ft sidewalls and a 9 ft peak takes 26.125 ft of pipe per frame and is 10.50 ft wide at 6 ft. A round hoop with 2 ft sidewalls and the same 9 ft peak takes 25.991 ft and clears 11.49 ft, with almost the same 1,032 vs 1,042 sq ft of covering.

Comparing frame types in the hoop house calculator shows that a curve wins on headroom for nearly the same pipe.

An 8 × 24 ft lean-to with a 5 ft front wall rising to 9 ft at the building needs 13.944 ft of pipe per frame and 447 sq ft of covering. The building wall is not glazed, so it stays out of the covering and the 33,784 BTU/h heater size.

Standard Hoop House Measurements by Pipe Length

Hoop houses have no single standard size, but the common pipe lengths push most DIY builds toward a few widths. Pipe and PVC conduit sell in 10 ft and 20 ft sticks, so bows of 20, 30 and 40 ft come up again and again. Setting the stick length in the hoop house calculator keeps the joints honest.

The table bends each bow into a half circle with no sidewalls. Film width adds a 2 ft flap on each side, matching the extra 4 ft that Bootstrap Farmer's film sizing guide adds to the measured arch.

Bow Length	Width at Ground	Peak Height	Width With 6 ft Headroom	Roof Film Width
10 ft	6.37 ft	3.18 ft	None (low tunnel)	14 ft
20 ft	12.73 ft	6.37 ft	4.26 ft	24 ft
24 ft	15.28 ft	7.64 ft	9.46 ft	28 ft
30 ft	19.10 ft	9.55 ft	14.86 ft	34 ft
40 ft	25.46 ft	12.73 ft	22.46 ft	44 ft

A single 20 ft stick bent into a half circle feels tall on paper, yet only the middle 4.26 ft clears a 6 ft person. Joining a 20 ft and a 10 ft stick into a 30 ft bow gives almost 15 ft of standing width, which is why many backyard plans use that pair.

Commercial high tunnels run wider. The University of Arizona Extension lists low tunnels around 4 × 10 ft and high tunnels from 14 to 40 ft wide by 100 ft or more.

Plastic Hoop House Calculator: Film and Endwalls

The roof sheet is one piece that runs over every hoop. Its width is the bow plus a flap on each side for burying, a base board or a roll-up side, and its length is the house length plus an overhang at each end to wrap the end hoops.

$$F_w=\lceil B+2f\rceil ,F_l=\lceil L+2e\rceil$$

F_w and F_l are the film width and length rounded up to whole feet, f is the flap per side and e is the overhang per end. With a 21.99 ft bow, 2 ft flaps and 3 ft overhangs, the 14 × 32 ft house needs a 26 × 38 ft sheet, or 988 sq ft.

Endwalls are cut from separate pieces. Each one starts as a rectangle as wide as the house and as tall as the peak plus one flap, then gets trimmed to the arch. Two 14 × 9 ft pieces add 252 sq ft before trimming.

Total covering area, the figure a hoop house area calculator reports, is the bow times the length plus both end areas. For the default house that is 21.99 × 32 + 2 × 76.97 = 858 sq ft, or 79.7 m².

Plan the length around the film you can buy. UMass Extension notes that 48 ft or 96 ft tunnels use 100 ft sheets with little waste, and it recommends 6-mil greenhouse-grade poly, rated for about 4 years, over agricultural film that usually fails within a year.

Wiggle wire and channel run along both sides, around both end hoops and across each endwall base. For the default house the hoop house calculator totals 136 ft: 64 ft of sides, 44 ft over two end bows and 28 ft across two endwalls.

Hoop House Pipe Size and Hoop Count

Hoop count is the length divided by the spacing, rounded up, plus one so there is a hoop at each end. A 32 ft house at 4 ft centers needs 9 hoops, and a 96 ft tunnel at the same spacing needs 25.

$$N=\lceil \frac{L}{s}\rceil +1$$

N is the number of hoops, L the length and s the on-center spacing. Four feet is the usual spacing on high tunnels, and the UMass fact sheet treats tunnel length as a multiple of that 4 ft spacing.

Pipe is bought by the stick, so a hoop house calculator should count sticks rather than total footage. A 21 ft 11-7/8 in bow uses one full 20 ft stick plus a 1 ft 11-7/8 in piece. Ten of those short pieces come from one stick, so 9 hoops need 10 bow sticks, not 11.

The full list for the default house is 15 sticks of 20 ft: 10 for bows, 2 for one ridge purlin and 3 for eighteen 3 ft ground posts. Each hoop has one joint, made with a swaged end or a coupler.

Picking a pipe size

Pipe diameter and wall thickness depend on width, snow and wind, not on geometry. The UConn high tunnel engineering guide notes that a 30 × 72 ft tunnel must carry a 10,800 lb load and that an 80 mph wind lifts the roof with about 220 lb per linear foot.

The hoop house calculator checks geometry, not strength. For loads like those, use the frame maker's rated hoop or a local engineer's design. Set the stick length to what your supplier sells, and if a short leftover piece shows up on every hoop, a slightly narrower width or lower peak can remove that joint.

PVC hoop house sizing

PVC works for small, light-snow builds. The National Gardening Association plan uses 1 in Schedule 40 gray electrical PVC in 10 ft lengths, with 7 ft roof pipes that make a structure 11 ft 4 in wide and 5 ft 7 in tall.

When you use the hoop house calculator for a PVC build, set the stick length to 10 ft so the stick count and joints match real conduit. PVC softens in summer heat and sags under snow, so keep spacing at 4 ft or closer and add a ridge purlin.

Hoop House Heat Loss and Heater Size

A hoop house loses heat two ways: through the covering, and through air that leaks out and is replaced by cold air. The heater must replace both at the design night temperature, then cover its own efficiency loss. A hoop house heat loss calculator that skips air leakage undersizes the heater.

$$Q_c=A\times U\times \Delta T\times W$$

$$Q_a=0.02\times V\times N\times \Delta T\times W$$

A is the covered area of the shell including both ends, in sq ft. U is the covering's heat loss factor in Btu/h per sq ft per °F. ΔT is inside minus outside temperature, V is air volume in cu ft, N is air changes per hour and W is the wind factor.

The conduction formula and the 0.02 air factor come from the University of Connecticut extension method. The National Greenhouse Manufacturers Association heat loss guideline uses 0.018 for the air term, so 0.02 adds a small safety margin. Wind on both terms follows the University of Arkansas greenhouse heating method.

Worked heater example

The 14 × 32 × 7 ft round house has 857.7 sq ft of closed shell. With single poly at U 1.15, a 50°F rise and 1 air change per hour, conduction is 49,315 BTU/h and air leakage adds 2,463 BTU/h, for 51,778 BTU/h of total heat loss.

An 80% efficient heater must be rated for 51,778 ÷ 0.80 = 64,723 BTU/h. At 91,452 Btu per gallon, that burns 0.71 gallons of propane per hour at full fire, or $1.77 per hour at $2.50 per gallon.

The same house as a 9 ft gothic needs 73,639 BTU/h because the taller arch adds 115 sq ft of film and 527 cu ft of air. Taller always costs heat, so match the peak to the crops and the work, not to looks.

Hoop house heat loss by covering

The covering choice moves the heater size more than any other input. These U-values come from Texas A&M AgriLife Extension, with the polycarbonate values from the NGMA guideline. Heater sizes are for the 14 × 32 × 7 ft house at a 50°F rise and 1 air change.

Covering	U-Value (Btu/h·ft²·°F)	Heater Size	Change vs Single Poly
Single poly film	1.15	64,723 BTU/h	Baseline
Single glass	1.13	63,651 BTU/h	-1.7%
Fiberglass	1.00	56,682 BTU/h	-12.4%
Double poly, inflated	0.70	40,601 BTU/h	-37.3%
Double glass	0.65	37,921 BTU/h	-41.4%
Polycarbonate, 6 mm	0.72	41,673 BTU/h	-35.6%
Polycarbonate, 8 mm	0.65	37,921 BTU/h	-41.4%
Polycarbonate, 16 mm	0.58	34,169 BTU/h	-47.2%

Switching the hoop house calculator to double inflated poly also lowers the air changes, since a tighter skin leaks less air. Dropping the air changes from 1.0 to 0.7 with it brings the heater down to 39,678 BTU/h, about 39% smaller than single poly. That is the cheapest heating upgrade on most hoop houses.

For metric users in India, Australia or elsewhere, U 1.15 equals about 6.5 W/m²·K, the single-layer figure NSW Department of Primary Industries lists. The hoop house calculator also accepts meters, centimeters, °C and km/h.

Air changes and wind

Air leakage depends on how tight the house is. The NGMA suggests 0.60 to 1.00 air changes per hour for new film-covered houses, 1.00 for structured sheet, and 1.50 to 4.00 for older houses depending on upkeep.

Construction (NGMA)	Air Changes per Hour
New, plastic film covered	0.60 to 1.00
New, structured sheet	1.00
New, single glass, laps sealed	1.00
New, single glass, laps unsealed	1.25
Old, good maintenance	1.50
Old, poor maintenance	2.00 to 4.00

Design winds above 15 mph raise heat loss. The NGMA wind factor is 1.04 at 20 mph, 1.08 at 25 mph, 1.12 at 30 mph and 1.16 at 35 mph, which works out to 0.8% more loss per mph above 15.

The hoop house calculator applies that factor to both the covering and the air leakage, as Arkansas does, while the NGMA applies it to the covering only. At 30 mph the default house needs 72,489 BTU/h instead of 64,723.

Hoop House Cost per Square Foot

A basic high tunnel costs about $1 to $2 per square foot of floor, according to UConn Extension. New Mexico State University puts a DIY build near $2.50 per square foot.

Wider ranges show up across sources. N.C. A&T Cooperative Extension lists single-bay material costs from 50 cents to $3.50 or more per square foot, and Oklahoma State Extension compares that with greenhouses that can reach $20 per square foot.

The hoop house calculator prices the film and pipe sticks at your local prices. For the default 448 sq ft house, $186 of film and $420 of pipe come to $606, or $1.35 per square foot, before fittings, wiggle wire, base boards, doors and ventilation.

Hoop House Build and Care FAQ

Unless an answer names another size, its numbers come from the hoop house calculator run on the 14 × 32 ft round reference house with a 7 ft peak, single poly film and 4 ft hoop spacing.

How do I use the hoop house calculator?

Start with the width, length and peak height you have room for, then pick round or gothic. If you already own bent hoops or pipe, the hoop house calculator can work from the bow length instead and return the peak height that pipe gives at your width.

Next, set the hoop spacing and the stick length your supplier sells, and the flap and overhang you plan to bury or wrap. For heating, use the night temperature your crop needs and your local winter design low, since the heater size covers both film loss and air leakage at that gap.

How do I calculate bulk materials for a hoop house?

Work from the hoop count. Multiply hoops by bow length for bow pipe, add purlin rows times the length, and add two ground posts per hoop. Then size the roof sheet, the endwall pieces and the wiggle wire for both sides, both end hoops and the endwall bases.

For a 14 × 32 ft round house with a 7 ft peak, the hoop house calculator bulk list is 15 sticks of 20 ft pipe, 18 ground posts, one 26 × 38 ft roof sheet, 252 sq ft of endwall film, 136 ft of wiggle wire and channel, and 64 ft of base board.

How do you calculate hoop size?

Hoop size comes from the width and peak height. For a half circle, multiply the width by π and divide by 2, so a 10 ft wide hoop needs a 15.71 ft bow and stands 5 ft tall. For any other shape, a hoop size calculator has to use the ellipse or gothic arc formulas above.

How do I design a hoop house?

Design from the inside out. Decide the bed and path layout, then pick a width that fits whole beds and a profile that gives 6 ft or more of headroom over the paths. Next choose a length that uses film sheets well, such as 48 ft or 96 ft with 100 ft sheets.

Sidewalls, a gothic peak, spacing and purlins are all ways to customize a hoop house, and each one changes the pipe and film count in the hoop house calculator. Short sidewalls add usable width at the edges, a gothic peak sheds snow, closer spacing adds strength, and extra purlins stiffen the frame against wind.

What is the difference between a hoop house and a greenhouse?

A hoop house is a pipe-frame arch, usually covered with one layer of poly film, with crops planted in the ground. A greenhouse uses rigid glazing, a permanent foundation and full heating, ventilation and benches, which is why it can cost ten times as much per square foot.

UConn defines a high tunnel as a walk-in, hoop or gothic frame covered with a single film layer, used to stretch the season by about a month in spring and a month in fall.

Greenhouse types also include gable, lean-to, arched and Quonset designs. A greenhouse hoop house calculator that covers gable and lean-to frames as well as round and gothic hoops lets you compare all four on the same footprint before buying.

How much does it cost to build a 10,000 square foot greenhouse?

As single-bay high tunnels, 10,000 sq ft costs roughly $5,000 to $35,000 in materials at N.C. A&T's 50 cents to $3.50 per square foot. As a conventional greenhouse at up to $20 per square foot, the same floor can reach $200,000.

Heating scales with size too. One 30 × 96 ft round tunnel with a 15 ft peak needs a 334,697 BTU/h heater in the hoop house calculator to hold 50°F at 10°F outside, or 3.66 gallons of propane per hour.

How do I calculate plot size for a hoop house?

Multiply length by width for the floor, then add room around it for anchors, drainage and snow that slides off the sides. A 12 × 12 area is 144 sq ft, and a 100 by 100 plot is 10,000 sq ft with 400 ft of perimeter, enough for three 20 × 90 ft tunnels with access lanes around them.

A plot has no single fixed size, since lot and garden plot sizes vary by town and program. To fence the site, the Rectangle Fence Perimeter Calculator gives the run length, and the Fence Calculator counts posts and rails.

How to build a hoop house?

Square the site by checking that both diagonals match, then drive ground posts at each hoop location. Set the bows over the posts, fasten the ridge purlin, frame the endwalls and doors, attach base boards and channel, and pull the film on last.

The Fence Post Depth Calculator helps set endwall and door posts. Cover the house on a calm, mild day, since warm film stretches and fits tighter once it cools.

How long does a hoop house last?

The film wears out first. UMass Extension rates 6-mil greenhouse-grade poly at about 4 years, while agricultural-grade film often fails within one season. A galvanized steel frame lasts for decades with basic care, so plan on re-covering several times.

What size PVC for a hoop house?

For narrow builds, 1 in Schedule 40 PVC is common, as in the National Gardening Association plan for an 11 ft 4 in wide house. Wider spans, heavy snow or high wind need steel tubing sized by the frame maker, because PVC bends under load and heat.

Which direction should a hoop house face?

Oklahoma State Extension says gutter-connected tunnels should run north to south to avoid shading each other, and any tunnel needs at least six hours of sun a day. For a single tunnel, NMSU notes that an east-to-west layout favors winter sun penetration.

How do I maintain a hoop house?

Retighten the wiggle wire after the first warm spell, patch tears with greenhouse repair tape, and brush off heavy snow before it loads the bows. Vent on sunny days, even in winter, and replace the film when it reaches the end of its rated life.

How do I select a greenhouse heater?

Size the heater from total heat loss at your design low, which is what a hoop heater size calculator should report. The NGMA points to the ASHRAE 97.5% winter dry bulb temperature, so the heater still keeps up on all but the coldest few hours of the year. Enter that low in the hoop house calculator, not an average night.

Pick a unit rated at or above the calculated BTU/h after efficiency, and vent any fuel-burning heater, as Texas A&M advises. Electric heat avoids flue gas, but at 3,412 Btu per kWh, a 51,778 BTU/h loss draws about 15 kW.

Can I run hoop house formulas in Excel?

Every hoop house calculation formula here except the curved arcs works in a spreadsheet. Hoops are =ROUNDUP(L/S,0)+1, a half-circle bow is =PI()*W/2, film width is =ROUNDUP(B+2*F,0), and heat loss is =A*U*(Ti-To)+0.02*V*N*(Ti-To).

The ellipse arc for a round hoop at any other height has no simple spreadsheet formula, and gothic arcs need the arctangent step above. That is where an online hoop house calculator saves time over a spreadsheet or an app.

What else fits inside a hoop house?

Many growers winter poultry in one end. The Chicken Coop Size Calculator sets floor space per bird, and for a solid-walled building instead of a tunnel, the DIY Shed Cost Calculator and Lean To Cost Calculator price the alternatives.