Fence gate calculator

Wide leaves automatically pick three hinges when you leave hinges_per_leaf blank; narrow leaves stay on two, and you can override either choice. Zero or negative gate width is rejected with invalid_input instead of inventing hardware, and non-positive gate counts fail the same way.

How gate posts, hinges, and latches are counted from openings and width

When you omit hinges_per_leaf, the calculator measures leaf width as gate_width divided by leaves_per_gate and applies a simple yard rule: two hinges if the leaf is at most the hinge width threshold (default five in whatever length unit you used for width), three hinges if the leaf is wider. That rule mirrors common residential practice where heavier or taller wide leaves get a third hinge for sag control; it is not a structural engineering certificate and you can always force an explicit hinges_per_leaf from one through ten. Latches equal the number of openings: one latch assembly per opening covers a single-gate thumb latch or a double-gate drop-rod-and-latch kit at the shopping-list level. Total opening width is openings times gate_width so you can cross-check how much fence run the gates replace. On success the response echoes rounded inputs, publishes gate_posts, hinges, latches, leaf_width, hinges_auto, formula, message, and steps so you can audit the arithmetic by hand or pin it in automated tests.

How to call the API and what comes back

String forms of whole numbers and decimals are accepted when they match a strict finite numeric pattern; fractional gate or leaf counts are rejected. Prefer sending numbers rather than pre-formatted strings when you control the client; when you must send strings, avoid unit suffixes or thousand separators that would fail the finite-number pattern. Send a JSON body with two required fields: gates (aliases gate_count, num_gates, n_gates, openings) as a positive integer from one through one thousand, and gate_width (aliases width, opening_width, gate_w, W) as a finite positive number within the published absolute range. Optionally send leaves_per_gate (aliases leaves, panels, leaf_count) as one or two—default one when omitted; hinges_per_leaf (aliases hinges_each, hinges_per_panel) as a positive integer up to ten; and hinge_width_threshold (aliases wide_gate_threshold, hinge_threshold) as a positive number in the same unit as gate_width—default five when omitted and only used for auto hinge selection. On success the response sets gate_posts to gates times two, hinges to the product of gates, leaves_per_gate, and hinges_per_leaf, latches to gates, total_opening_width to gates times gate_width, leaf_width to gate_width divided by leaves, hinges_auto true when hinges were chosen from the threshold rule, formula to the posts hinges latches expressions, message to a short English summary, and steps to an ordered substitution log. Failed validation—missing fields, non-finite numbers, zero or negative width, non-positive gate counts, leaves outside one or two, hinges outside one through ten, or values outside absolute limits—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item.

Practical tips, limits, and related searches

Keep gate counts inside one through one thousand and dimensions inside the published absolute range so counts remain safe integers. Call once per distinct opening size if widths differ, then sum posts, hinges, and latches across calls. Round-trip checks are easy: recompute two posts per gate, multiply leaves and hinges per leaf, set latches equal to gates, and confirm the published integers match. Measure the clear opening between finished posts or between the planned post faces, not the panel blank before trim, so gate_width matches what you will hang. For a four-foot walk gate use leaves_per_gate one and leave hinges auto or set two; for a ten-foot driveway double gate use leaves_per_gate two so each five-foot leaf is evaluated for the third hinge when the default threshold is five. If your region always uses three hinges regardless of width, set hinges_per_leaf explicitly and ignore the threshold. When teaching or writing tests, pair a narrow single gate that auto-selects two hinges with a wide leaf that auto-selects three, add an explicit hinges_per_leaf override, and include a deliberate zero or negative gate_width to prove the invalid_input path. This landing targets people searching for a fence gate calculator, how many hinges for a gate, gate posts and latches material list, or double gate hardware counts online; it is not a fence post spacing tool for the long runs between openings, not a picket or board counter, not a concrete post-hole volume estimator, and not a wind-load or code compliance engine. Prefer home.fence_posts when you already know run length and post spacing for the solid fence segments, and prefer this capability when the question is only gate hardware. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when you deliberately send bad widths to verify error handling.