Hexagon Deck Calculator
Size a regular 6-sided deck — the classic gazebo footprint. Area = (3√3/2)·s². The simplest geometric shape: only 6 mitred rim segments at 30°, 6 vertex posts, and decking that runs parallel to any pair of opposing sides. DeckMath returns flat-to-flat, vertex-to-vertex, chord-joist count, posts + footings, 13-18% decking waste — lowest of the geometric shapes.
Inputs
Hexagon dimensions
Compliance · IRC + framing notes
No guardrail required — 24″ off grade < 30″
IRC R312Under 30″ off grade, IRC R312 does not mandate a guardrail. Hexagon gazebo decks at gazebo-deck height (12-24″) often skip the railing for an open gazebo aesthetic.
Chord joists — 10 joists at 16″ o.c. (102 lf total)
IRC R507.6 + AWC DCA-6Joists run parallel across flat-to-flat (12.12′). Center joist spans full vertex-to-vertex (14′ = 2·s); outermost joists are shortest (= s = 7′ at the very flat edges). Total 102 lf — ~73% of full-length joist stock.
6 corner posts only — no center post needed (12.12′ flat-to-flat ≤ 14′)
IRC R507.5 + DCA-6Hexagons under 14′ flat-to-flat are framed with corner posts only (one per vertex). 2×10 PT joists span the full flat-to-flat at 16″ o.c. without intermediate support.
Decking waste — 14% (30° mitre cuts)
Industry standard waste %Hexagons waste 13-18% of decking — between rectangle (7-10%) and octagon (15-20%), much lower than round (25-28%). Only 6 mitre cuts per row, all at 30° (standard chop-saw setting). Composite hides 30° mitre imperfections cleanly — lowest waste of the surface options.
Bill of materials
Hexagon deck pricing 2026-Q1. 14% decking waste baked in (30° mitre premium — lowest of the geometric shapes). Labor 1.22× regional × ~1.25× hexagon.
Regular hexagon = 6 equal sides at 120° interior angles. Area = (3√3/2)·s². Most DIY-friendly geometric deck — only 6 mitres at 30° each. Engineer review recommended above 16′ flat-to-flat.
How to use
How to use the hexagon deck calculator in 5 steps.
- 1
Set side length
Side length (s) is the length of ONE hexagon side. s=7′ → 12.1′ flat-to-flat, 14′ vertex-to-vertex, 127 sqft. s=10′ → 17.3′ flat-to-flat, 20′ vertex-to-vertex, 260 sqft. Most hexagon decks use 6-10′ sides — the size of a standard gazebo footprint.
- 2
Pick height + railing
Above 30″ off grade triggers IRC R312 — 36″ guardrail around all 6 segments. Hexagon rail joints are at 60° exterior angles (120° interior) — every cap-rail system sells 60° or 30° corner connectors off-the-shelf.
- 3
Pick surface material
PT pine ($1.95/lf — cheapest, 16% waste), cedar ($3.40/lf — gazebo classic, 18% waste, stainless screws req), composite mid Trex Enhance ($3.80/lf — best value, 14% waste), composite premium Trex Transcend ($5.40/lf — premium, 13% waste), Ipe ($7.80/lf — 50-yr hardwood, 18% waste).
- 4
Post size + center post
6×6 PT at all 6 vertices for spans >10′ flat-to-flat. 4×4 works for small hex decks under 10′ flat-to-flat with no railing. Above 14′ flat-to-flat, add a center support post to halve the joist span — DeckMath auto-flags this.
- 5
Read your hexagon deck cost
Project total, $/sqft, area, perimeter, flat-to-flat + vertex-to-vertex dimensions, post + joist + footing counts, BoM, share link, PDF/CSV export.
How we calculate
How DeckMath calculates this — IRC 2021 sources.
The Hexagon Deck Calculator sizes a regular 6-sided deck — the classic gazebo footprint with 120° interior angles. The simplest of the geometric deck shapes: only 6 mitred rim segments at 30°, 6 vertex posts, and decking that runs parallel to any pair of opposing sides. Pick side length (3–16′), height, surface, post size, and state. DeckMath returns area (using (3√3/2)·s²), flat-to-flat dimension, vertex-to-vertex span, chord-joist count, 6 corner posts + optional center, mitred-rim BoM, 13-18% decking waste (lower than octagon's 15-20%, much lower than round's 25-28%), and a 36″ railing line item when height exceeds 30″ (IRC R312). Labor premium is +15-40% vs rectangular — the lowest of any geometric shape because only 6 mitres are involved.
IRC references
- IRC 2021 R507.6 — Joist span (chord joists size to longest chord = 2·s at vertex-to-vertex axis)
- IRC 2021 R507.5 — Beam span (6-segment perimeter beam — each segment is one hexagon side)
- IRC 2021 R507.3 — Footings at each of 6 vertices + optional center
- IRC 2021 R312 — 36″ guardrail required ≥ 30″ off grade
- AWC DCA-6 — Prescriptive deck framing (hexagon framing common; engineer review recommended above 16′ flat-to-flat)
Hexagon deck pricing 2026-Q1. Decking waste 13-18% (30° mitre premium — lowest of the geometric shapes). Labor 1.15-1.40× rectangular deck. Geometry coefficients exact: flat-to-flat = √3·s, area = (3√3/2)·s², vertex-to-vertex = 2·s.
Regular hexagon area as a function of side length. s=6′ → 94 sqft. s=8′ → 166 sqft. s=10′ → 260 sqft.
Distance across the hexagon between two parallel sides — the framing-square width. s=7′ → 12.1′ flat-to-flat. Use this dimension when ordering 14′ joists from the lumber yard (one length spans full flat-to-flat).
Distance across opposite corners — exactly twice the side length. s=7′ → 14′ corner-to-corner. The hexagon's longest dimension. Used for sizing the gazebo umbrella spread or the central skylight in a roofed hex.
Joists span across flat-to-flat at 16″ o.c., each cut to chord. Center joist runs through the vertex-to-vertex axis (longest at 2·s). Outermost joists are at the very flat edges (shortest at the side length itself = s). Total joist linear feet ~75-80% of square-frame full-length joists.
Lower than octagon (15-20%) or round (25-28%) because hexagons have only 6 mitre cuts per row of decking. Composite hides cuts best (13-14%); cedar + Ipe waste 18% from 30° mitre splintering.
Lowest premium of any geometric shape. PT 1.15× (chord joists + 6 mitre cuts). Composite 1.25× (hidden fastener at mitred ends). Ipe 1.40× (predrill every angled fastener). DIY-friendly with a chop saw set to 30°.
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People also ask
Hexagon deck questions, answered.
An 8′-side hexagon has 166 sqft area, 48′ perimeter, 13.9′ flat-to-flat, and exactly 16′ vertex-to-vertex (always 2·s for a regular hexagon). This is a popular gazebo-deck size — fits a 6-person hot tub centered with 2′ clearance, or 6-chair patio dining set with center umbrella.
$30-55 per square foot installed depending on surface, height, and railing. An 8′-side hexagon (166 sqft) in composite mid-tier with 36″ railing: $6,000-9,500. Same footprint in PT pine without railing: $4,000-6,500. Hexagons cost ~15-20% more than the same square-footage rectangle (vs +25-35% for octagon, +35-60% for round) — they're the cheapest geometric shape.
Three reasons: (1) Only 6 mitre cuts per row vs 8 (octagon) or 12-32 (round); (2) Decking waste 13-18% vs 15-20% (octagon) or 25-28% (round) — fewer angled edge cuts; (3) Standard 30° mitre angle is on every chop saw — DIY-friendly. The trade-off: hexagons look 'less round' than octagons, which matters if the aesthetic is the goal.
Orient the hexagon with two flat sides on top + bottom. Build a rectangular outer joist frame whose width = s·√3 (flat-to-flat) and length = 2·s (vertex-to-vertex). Run joists at 16″ o.c. across the flat-to-flat dimension. Cut each joist to its hexagonal chord — center joist spans the full vertex-to-vertex (2·s); outermost joists are short (= s). 6 corner posts (one per vertex) + doubled-2×10 perimeter beam under the rim. Optional center post for spans >14′ flat-to-flat.
6 posts at minimum — one at each vertex of the hexagon (where two sides meet at 120°). 6×6 PT recommended for spans >10′ flat-to-flat; 4×4 works for small gazebos under 10′ flat-to-flat with no railing. Above 14′ flat-to-flat, add a 7th center post — DeckMath auto-flags this when your dimensions exceed the threshold.
Use 2×10 PT joists for hexagons up to 14′ flat-to-flat (no center post). Use 2×12 PT or add a center post for 14-18′ flat-to-flat. Joist spacing is 16″ o.c. for PT/composite; 12″ o.c. for Ipe or hidden-fastener composite. The center joist on the vertex-to-vertex axis spans 2·s — this is the longest joist and determines lumber stock length (8′-side hexagon needs 16′ joist stock).
Yes — hexagon decks are a popular hot-tub footprint because the 6-sided shape mirrors many hot-tub corners. Use the Hot Tub Deck Calculator for reinforcement: a typical 7×7 hot tub (~5,000 lb filled) on an 8′-side hexagon (166 sqft) needs 12″ o.c. joist spacing under the tub footprint + 14″ Ø footings under the 4 nearest perimeter posts. Total deck rating: 100 psf live load (vs 50 psf normal) under the tub zone.
Composite mid-tier (Trex Enhance, $3.80/lf, 14% waste) is the best value — lowest waste, hides 30° mitre imperfections, 25-yr warranty, color-matched fascia trim wraps the 6 segments cleanly. Cedar is the gazebo classic look — the hexagon is a 100-year-old gazebo footprint, and cedar matches that aesthetic. PT pine is cheapest but every 30° angled cut needs annual stain. Ipe is overkill for a hexagon — the predrill labor savings only matter on rounds, not hexagons.
Yes — hexagons are the most DIY-friendly geometric deck. Only 6 mitre cuts at 30° each (standard chop-saw setting), 6 corner posts laid out from a center point with a string compass, and decking that runs parallel to any pair of opposing sides. Intermediate DIY: 2-4 weekends for a 6-8′ side hexagon. Beginner DIY: doable if you've built one rectangular deck before. Compare: octagons are marginal-DIY (8 mitres), rounds are pro-only.
Hexagon: 15-20% cheaper, easier DIY, classic gazebo look, but visibly less round. Octagon: more circular aesthetic, 25-35% premium over rectangle, mid-difficulty DIY, more posts (8 vs 6). If you want gazebo vibes + DIY-doable, hexagon. If you want the deck to read as 'almost-round' at a glance, octagon. If you want truly round, use the Round Deck Calculator (24+ facets).
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