About PipeCalcs
PipeCalcs is an independent project with one goal: to gather the everyday calculations homeowners, DIYers and buyers reach for across an interior plumbing project — water-heater sizing & cost, water-supply pipe sizing, drain / waste / vent sizing, fixtures & water use, gas piping, and whole plumbing-project cost — in one focused, free, no-signup hub with transparent formulas.
Who is behind it
Author and curator
To be clear about credentials: I am the author and curator of this site — not a licensed master plumber, gas fitter, mechanical engineer or financial advisor. What I bring is relevant and real: building deterministic online calculators (open-source Python projects) and engineering training, i.e. rigor on the arithmetic and physics. That is what it takes to curate a hub of calculators: transparent method, correct formulas, cited conventions and worked examples.
Our principle: transparent & durably correct
Every calculator shows its formula, a worked example and a reference table. The tools rest only on timeless plumbing math (tankless BTU/hr = GPM × 500 × ΔT; recovery GPH = BTU/hr × efficiency ÷ (8.34 × ΔT); pressure head = psi × 2.31; pipe volume = 0.0408 × diameter² × length; drain fall = length × slope; gas CFH = BTU/hr ÷ heating value; cost = quantity × your unit price) and stable conventions (7.48 gallons per cubic foot; 1 psi = 2.31 ft of head; nat-gas 1000 / propane 2516 BTU per cubic foot; WSFU/DFU and pipe-size planning bands). There are deliberately no material or service prices, labor rates, regional cost indexes or live loan rates — cost tools use the prices you enter — so the results stay valid over time.
Correctness is checked against known reference values (see the methodology and the numeric self-check). The formulas and their basis are documented under Sources & formulas. All results are planning estimates: get itemized written quotes from licensed plumbers; pipe, drain, vent and gas sizing follows conventions but your local plumbing code and inspector govern — confirm with a licensed plumber and pull the required permits; all gas work must be done by a licensed professional with a permit and inspection; savings and comparison tools are illustrative math on your figures, not financial advice. Questions? Use the contact page.