Stair headroom calculator

Failed validation is not billed; successful item calls use the published $0.002 base price on KIT balance.

Measure floor-to-floor height, pitch angle and opening length in one unit system

Send floor_to_floor_height as a strictly positive finite number; aliases floor_height, storey_height, total_rise and height map to the same field. Send stair_angle with aliases angle, pitch_angle, pitch and slope_deg. Send floor_opening_length with aliases opening_length, opening, well_length and stairwell_length. Zero or negative dimensions raise invalid_input and are not charged. Extremely small or huge values outside the published stability range also fail so floating-point results stay meaningful on a Worker isolate.

How available headroom, total run and the code check are computed

Over the opening length L the pitch line rises by L times tan of theta; that rise is the geometric vertical distance from the pitch line at the lower soffit edge up to the finished upper floor plane. Optional slab thickness T is then subtracted so available headroom equals L times tan of theta minus T, matching clearance to the underside of structure rather than to the finished surface when T is known. Opening_covers_run reports whether the opening is at least as long as the total run. For a straight flight that lands at the far end of the upper-floor opening, the horizontal run needed to climb floor-to-floor height H at angle theta is total_run equals H divided by the tangent of theta. The default code minimum is two thousand thirty-two of your linear unit—the familiar six feet eight inches figure when you work in millimetres—or you override min_headroom with aliases code_minimum, required_headroom and min_clearance. Headroom margin is available minus minimum; meets_code is true when available is at least the minimum. Required opening length is the shortest L that still meets the minimum for the same angle and slab: (min_headroom plus slab) divided by tan of theta. The response echoes inputs, reports total_run, rise_over_opening, available_headroom, required_opening_length, headroom_margin, meets_code and opening_covers_run, and sets method to stair_headroom for stable branching. Identical inputs always produce identical JSON because the path is pure trigonometry and arithmetic with no network, random seed or wall clock. This product does not replace a licensed design review; treat the numbers as a layout check and verify against your jurisdiction before construction.

API usage, pricing, renovation workflows and practical limits

Call the free in-browser stair headroom calculator for quick home estimates, loft conversions and contractor whiteboards without opening a spreadsheet. Remember that nosing projection, bulkheads, door swings under the half-landing and local code measurement points can change the effective critical clearance even when the simple soffit-edge geometry looks fine—adjust inputs to match the section you will actually build. Send a JSON body with required floor_to_floor_height, stair_angle and floor_opening_length, plus optional min_headroom when your code uses a different clearance and optional slab_thickness when the upper floor structure is known. Use the prepaid API when a renovation app, takeoff tool, configurator or property pipeline needs a stable contract under KIT balance at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. Pair this endpoint with a staircase step or rise-and-run calculator when you still need tread counts and exact risers, or with unit converters when drawings mix systems. Authors shipping SDKs can map meets_code and required_opening_length into plan checks while showing available_headroom and headroom_margin as explanatory detail for the homeowner or site supervisor reviewing the stairwell.