These calculators were built by Rebend Industries, an Australian trade tool company founded by plumbers with 50+ years experience on the tools doing the work. We built them because we wanted quick, reliable reference tools that actually work the way tradies think on the job. No signing in or email signup, just punch in your numbers and get your answer. Save these calculators in your phone for even quicker reference.

Yep, completely free. No account, no email, no catch. We built these as a resource for the trade community because we reckon good information should be accessible to everyone, whether you're a licensed plumber, a first year apprentice, or a homeowner trying to understand what your plumber is talking about.

These calculators are for sewer only. Stormwater generally needs less grade than sewer, so the requirements are different. If enough people reach out and let us know they want a stormwater calculator, we'll get one in the works.

These calculators are designed for use in Australia and New Zealand, as that's where our 50+ years of plumbing experience has been. All calculations reference Australian and New Zealand plumbing standards, so if you're working under local codes here, you're covered. We're looking at adding support for other countries down the track, so stay tuned.