Hoop house calculator

This hoop house calculator takes three strictly positive lengths in one unit—house length along the row of hoops, span width between the ground rails, and center-to-center hoop spacing—and returns hoop_count and cover_area for a Quonset (semicircular) model. Missing, zero, or negative dimensions fail with invalid_input and are not billed.

How hoop count and plastic film area are computed

Greenhouse film that drapes over the bows must cover that arc along the full length, which is a rectangle of area hoop_arc_length times length, or pi times width times length over two. Each end wall is a semicircular disk; two of them together equal a full circle of radius width over two, so end_wall_area is pi times width squared over four. Adding those pieces gives the cover_area this calculator returns: pi times width times length over two, plus pi times width squared over four, which factors as pi times width over four, times two times length plus width. Hoops stand at both ends and at every hoop_spacing along the length, so hoop_count is the ceiling of length divided by hoop_spacing, plus one. All three inputs must share one linear unit so cover_area is that unit squared and hoop pipe is that unit of length.

What you send, which units to use, and how validation fails

Use one consistent length unit for all three fields: feet with feet, metres with metres, yards with yards. Mixing metres of length with feet of width would be meaningless, so the contract leaves conversion to the caller. Upper and lower limits keep intermediate products finite: each field must be at least 1e-15 and at most 1e12. Send three required numeric fields. length is a finite positive number for the house run from one end wall to the other; aliases L, house_length, and house_len are accepted. width is a finite positive number for the span between ground rails, which is also the diameter of each semicircular hoop; aliases W, span, and house_width are recognized. hoop_spacing is a finite positive number for the centre-to-centre distance between consecutive ribs; aliases spacing, S, hoop_space, and rib_spacing are accepted so a spreadsheet column named spacing does not need a rename. Strings that parse as finite numbers are accepted the same as JSON numbers. Cover area is then that unit squared and hoop_pipe_length is that unit of bow pipe. On success the response echoes the cleaned inputs, publishes hoop_radius as half the width, hoop_arc_length as pi times that radius, hoop_count as the integer bow total, hoop_pipe_length as count times arc, tunnel_cover_area for the half-cylinder, end_wall_area for both semicircular ends, cover_area as their sum, and formula restating the identities. A forty-eight by twelve house with hoop_spacing four yields thirteen hoops and cover_area equal to three hundred twenty-four pi. Validation failures name the offending field so a form can highlight length when someone types zero, or hoop_spacing when a sheet leaked a negative. Failed tasks return invalid_input and do not consume prepaid balance. Successful API calls use the published base of $0.002 per item.

Where a hoop house materials calculator earns its keep

School gardens, community farms, and extension desks need a hoop_count and cover_area that match the public calculator when a volunteer pastes the same three numbers into a storefront. Pin goldens in tests: forty-eight by twelve on four-unit centres must stay thirteen hoops, and cover_area must stay three hundred twenty-four pi after twelve-decimal rounding. Round-trip checks are easy: recompute ceil of length over spacing plus one by hand, add the half-cylinder and two semicircles, and confirm hoop_count and cover_area match.