Nine free calculators for pipes, wells, and water heating — sizing math computed from public engineering formulas and your own numbers, with the working shown. Free, no signup, runs entirely in your browser. These are planning tools: for gas work and permanent installations, confirm against local code and a licensed professional.
Start at the source: the Well Pump Sizing Calculator turns well depth, system pressure, and fixture count into the pump’s required GPM and total dynamic head. With the pump’s flow known, the Pressure Tank Sizing Calculator gives the drawdown and tank size that keep it from short-cycling. From there, the Pipe Flow Calculator checks velocity and friction loss for the runs you’re planning, and the Pipe Volume Calculator tells you how much water the system actually holds — useful for treatment dosing and drain-down.
Count the fixtures that can run hot water at once and the temperature rise you need. The Tankless Sizing Calculator converts that flow and rise into the BTU/hr an on-demand unit must deliver, while the Water Heater Sizing Calculator sizes a storage tank from your household’s peak-hour demand — run both to compare the two approaches for the same house. If the heater is gas-fired, finish with the Gas Pipe Sizing Calculator to check the line can carry the appliance’s BTU load over your run length.
The Pipe Size Conversion Calculator translates between NPS, DN, and actual outside diameter when drawings and fittings disagree on naming, and the Pipe Weight Calculator gives the mass of a run for hanger spacing and transport.
Pump first, tank second, pipe last. The pump’s GPM and total dynamic head come from the well and the house’s demand; the pressure tank is then sized to that pump’s flow so it doesn’t short-cycle; and the piping is checked against the flow the pump delivers. The supply chain above links each step to its calculator.
Run both for the same house. The tankless tool sizes from simultaneous flow (GPM × temperature rise), the tank tool from peak-hour volume — the two numbers tell you which technology fits your usage pattern, and what size of each you’d need. Houses with short, overlapping draws often suit tankless; long soaking draws favor storage.
No. Every result here is computed from public engineering formulas and the numbers you enter — nothing is copied from code tables or manufacturer charts. That makes them honest planning estimates, but gas piping, well work, and water-heater installation are code-governed: verify against your local code and have the work done or checked by a licensed professional.
No. The calculators run as JavaScript in your browser; your inputs never leave your device and there’s no account or server involved.