Offline hydronic pipe-sizing & pump-head calculator for HVAC engineers — precise, fast, no subscription.
Have a question, found a bug, or want to request a feature? Reach out directly — every message is read by the developer.
Email duongnh@axalize.vnNo. The app is 100% offline — every calculation runs on your device, instantly, anywhere on a job site with no signal.
Size mode: enter flow plus a target head-loss rate or velocity to get the required inner diameter, the nearest nominal pipe size for your chosen material and schedule, and the resulting velocity, head-loss rate, and Reynolds number. Pump mode: build a segment list with lengths, pipe sizes, and fitting counts, add equipment pressure drops (coil, chiller, boiler, control valve) and static lift, and get the Total Dynamic Head (TDH) at design flow with a pipe/fittings/equipment/static breakdown — the number you need to actually select a pump.
In a closed loop (typical hydronic heating or chilled water), static lift cancels out — the fluid returns to the elevation it started from, so elevation must NOT be added to pump head. In an open loop (e.g. a cooling tower or open sump), static lift is real and is included. HydroSizer defaults to closed loop and only shows the static-lift field for open loops.
The default method is Darcy–Weisbach with the Colebrook–White friction factor, using temperature-dependent water density and viscosity. Hazen–Williams is available as an optional method in Settings (water-only, empirical — less accurate for hot water). Fittings can be computed by K-factor (Crane TP-410 based coefficients) or the equivalent-length method.
| Material | Dimension basis | Roughness (ε) |
|---|---|---|
| Steel, Schedule 40 (default) | ASME B36.10 | 0.045 mm |
| Copper, Type L | ASTM B88 | 0.0015 mm |
| Copper, Type M | ASTM B88 | 0.0015 mm |
| PEX (SDR-9) | ASTM F876 | 0.0015 mm |
| CPVC (CTS) | ASTM D2846 | 0.0015 mm |
Sizing always uses the material's actual inner diameter — a 1″ nominal steel, copper, and PEX pipe each have a different real bore, and HydroSizer accounts for that.
Yes — Settings lets you pick flow (GPM, L/s, m³/h), head-loss rate (ft/100ft, m/m, Pa/m, kPa/m), head (ft, m, kPa, psi), diameter (inch, mm), and temperature (°F, °C) independently.
Yes — English, Español, 中文, Português (Brasil), 日本語, 한국어, and Tiếng Việt are all supported. Switch under Settings → Language.
No. HydroSizer is a one-time purchase. There are no subscriptions, no ads, and no in-app purchases beyond the initial download.
No — see the Privacy Policy for details.