Free calculators and reference tools for Australian plumbers. Gas sizing, backflow, hot water, drainage, ventilation — all grounded in current AS/NZS standards. No account needed. We're building these in the open and improving them based on your feedback.
Calculators, compliance checks, and reference tools. Each one shows the reasoning and the standards reference so you can verify the answer yourself.
These tools are built by plumbers, for plumbers — but they're not perfect. If a calculation looks off, a standards reference is outdated, or something doesn't match what you see on site, we want to know. Every piece of feedback makes the tools better for everyone.
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No. All calculators run entirely in your browser. Nothing is sent to a server and nothing is saved. When you close the page, your inputs are gone.
All eight — NSW, VIC, QLD, SA, WA, TAS, NT, and ACT. State-specific requirements for backflow registration, hot water compliance, and TMV rules are built into the relevant tools.
These tools are guidance only. Every output references the specific AS/NZS clause it's based on so you can verify it directly. A plumber must verify all results against actual site conditions and the current edition of the relevant standard before carrying out any work.
A tempering valve (AS 4032.2) limits water temperature to 50°C at personal hygiene outlets — required for most residential hot water systems. A thermostatic mixing valve or TMV (AS 4032.1) is required in aged care, childcare, hospitals, and disability accommodation. TMVs have stricter fail-safe requirements and must be tested annually. Using a tempering valve where a TMV is required is a compliance failure even if both achieve the same outlet temperature.
Under AS/NZS 3500.2, a toilet pan outlet requires a minimum 100mm branch drain regardless of the fixture unit calculation. A low total DFU count does not permit a smaller pipe when a WC is connected. The drain sizing tool enforces this automatically.
Gross margin is profit as a percentage of the sell price. Markup is profit as a percentage of cost. A 30% margin on a $1,000 job means $300 profit. To hit that 30% margin, you need to add 42.9% to your cost — not 30%. Adding 30% to cost gives you a 23.1% margin. The job margin calculator shows both figures side by side so you don't confuse them.
Getting busy should feel like winning. But once the work starts stacking up, the business side — quoting, ordering, invoicing — starts slipping, and time becomes the real constraint.
Going out on your own, the work part is manageable. The business part — invoicing, chasing payments, staying on top of admin while you're flat out on the tools — is what catches most people off guard.
When I started out, I looked young and I was young — walking into jobs against guys who'd been doing it for twenty years. Here's what actually bridged that gap.