Carpentry Calculators Australia
Free carpentry calculators for Australian builders, carpenters and DIYers. Calculate deck boards and joists, fence palings and posts, stair geometry with NCC compliance checks, rafter lengths from roof pitch, and timber quantities in lineal metres, m³ and kg. All metric, all free.
Carpentry calculators
Deck Calculator
Deck boards, joists, posts and footing concrete. Enter deck dimensions and board size to get full materials list.
Open calculator →Fence Paling Calculator
Paling count, rails, posts and footing concrete for a timber paling fence. Includes 10% wastage option.
Open calculator → NCC complianceStair Calculator
Calculate riser height, going, number of risers and stringer length. Checks NCC BCA requirements for rise and going.
Open calculator →Roof Pitch Calculator
Convert between pitch ratio, degrees and percent. Get rafter length with and without eave overhang.
Open calculator →Timber Calculator
Lineal metres, volume (m³) and weight (kg) for any AU timber section. 20+ standard sawn and DAR presets.
Open calculator →Australian carpentry standards reference
- AS 1684 — Residential timber-framed construction. The main reference for timber framing in Australia. Parts 2 (non-cyclonic) and 3 (cyclonic) provide span tables for rafters, joists, bearers and lintels. Widely referenced in NCC Volume Two for Class 1 and Class 10 buildings.
- NCC Volume Two — Section 3 — Sets requirements for stair geometry in Class 1 buildings: rise 115–190 mm, going 240–355 mm (domestic), minimum stair width 600 mm, 2R+G comfort formula 550–700 mm recommended. The stair calculator checks these limits.
- AS 1170.1 — Structural design actions (dead and live loads). Used by engineers when sizing structural members for decks, floors and roofs. The deck calculator uses AS 1170 span assumptions as a guide for joist spacing.
- AS 1720.1 — Timber structures — design methods. The engineering standard for structural timber design; referenced when engineers size beams, rafters and posts beyond the prescriptive span tables in AS 1684.
- AS 3959 — Construction of buildings in bushfire-prone areas. Specifies timber types and treatment requirements for decks and external structures in BAL-rated zones. Relevant for decks in regional and outer suburban areas.
Common carpentry questions for Australian projects
What is the maximum rise and minimum going for stairs in Australia?
Under NCC Volume Two (Class 1 buildings — houses), the maximum riser height is 190 mm and the minimum going is 240 mm. The 2R+G formula (twice the rise plus the going) should fall between 550 mm and 700 mm for comfort, though this is advisory rather than mandatory. A stair width of at least 600 mm is required. The stair calculator checks all these limits automatically and shows a pass/fail panel.
What spacing should deck joists be in Australia?
Standard joist spacing for residential decks is 450 mm centres for 90 × 45 seasoned pine or hardwood joists with a span up to about 1.5–1.8 m between bearers. For 19 mm thick decking boards, joist spacing should not exceed 450 mm; for 32 mm thick boards, 600 mm centres may be acceptable. Always check the span tables in AS 1684 or have your engineer specify joist sizing for spans above 2.0 m.
What is a standard roof pitch in Australia?
Common roof pitches in Australia range from 15° to 35°. A 22.5° (1:2.5 ratio) pitch is a common middle-ground for terracotta and concrete tiles. Corrugated metal roofing (Colorbond) can be installed from as low as 5° with lapped joints and 3° with sealed joints. Hip roofs are typically 22–27°; gable roofs often 25–35°. Steeper roofs (>30°) shed water faster and suit areas with heavy rainfall, but require more material and stronger framing.
How many palings do I need per metre of fence?
For a standard 75 mm wide paling with a 5 mm gap, there are approximately 12.5 palings per lineal metre (1000 ÷ (75 + 5) = 12.5). For a 100 mm wide paling at 5 mm gap: approximately 9.5 palings per LM. The fence paling calculator works this out automatically for any paling width and gap combination, and adds posts, rails and footing concrete.
Do I need a building permit for a deck in Australia?
Generally yes, if the deck is attached to a dwelling, more than 1 m above ground level, or over a certain floor area (which varies by state — typically 10 m² in VIC, 25 m² in QLD and NSW for exemption consideration). A free-standing deck below 1 m may be exempt from a permit in some states, but it still must comply with structural and setback requirements. Check with your local council or a registered building surveyor before starting. All structural work on decks must comply with AS 1684 or be engineer-certified.