Free construction calculators for New Zealand builders
Free calculators for New Zealand builders, built against the free Acceptable Solutions and using New Zealand terminology. No signup.
What each calculator does, and what it hands off
- Lintel loaded dimension works out the roof and floor loaded dimensions a lintel table asks for, which is the input most people get wrong, and lists the other inputs you still need: wind zone, snow zone, roof mass and timber grade. It then hands off to the free BRANZ Lintels and Beams calculator for the member size, because the size itself lives in an NZS 3604 table.
- Stairs takes total rise, number of risers and tread depth, returns the riser height and pitch, and checks all three against D1/AS1 Table 6 for the stair class you pick. Picking the wrong class is the common mistake, so the page explains the four classes before the calculator.
Why there are only two
Most of what a New Zealand framing calculator would do is read a table out of NZS 3604, and those tables are copyright under section 27(1C) of the Copyright Act 1994 even though B1/AS1 cites the standard. A span, bracing, pile or stud calculator built from them would be a reproduction, including one rebuilt from scratch. What can be built is the calculator that produces the inputs the table needs, which is what the lintel page does, and the calculators whose limits sit in a free Acceptable Solution, which is what the stair page does. Concrete volumes, brick counts and the other pure geometry are the same everywhere and sit on the Australian set with no local figure attached.
Using them well
Everything is in millimetres unless the field says otherwise, nothing you enter is stored, and both run on a phone with no app. Where a result depends on an Acceptable Solution, the result panel names it, so you can check the figure against the copy your building consent authority is working from.
If a field asks for a stair class, a wind zone or a roof mass you are not sure of, the guide linked from that page explains where the figure comes from and which document to read it in, which is faster than guessing and running the calculator twice.
Why a separate set of calculators
Geometry is the same everywhere. A 3-4-5 triangle squares a building in Manchester exactly as it does in Melbourne. What changes is the rule the answer has to meet: the maximum riser on a stair, the minimum pitch a tile can be laid at, the gradient a ramp is allowed to run. These calculators check against the local rule, so the answer you get is one you can build to.
Take the numbers into the job
Built Simple keeps your estimates, schedule and crew in one place, on the phone in your pocket.
Frequently Asked Questions
Are these calculators free? Yes, with no account and no usage limit.
Do they follow the Building Code? They follow the Acceptable Solutions, which are the published route to satisfying the Code. D1/AS1 and F4/AS1 are free documents, so we can quote them directly.
Why is there no span table calculator? Because the span tables live in NZS 3604, which is copyright. The lintel calculator gives you the loaded dimensions the table needs and hands off to the free BRANZ tool for the member size.
