Free tools for fan engineers
The calculations we build into selection software every day, opened up as standalone calculators. No sign-up, no email wall, no watermark on the result — every tool states the standard it implements and links to the primary source, so you can check the arithmetic yourself.
ErP 2026 compliance calculator
Check a fan against Regulation (EU) 2024/1834, in force since 24 July 2026. Required minimum efficiency, the N grade applied, correction factors and the maximum input power that still complies.
EU 2024/1834 · LiveFan Energy Index calculator
FEI at any duty point per ANSI/AMCA 208-18, with the full reference fan chain and a check against the ASHRAE 90.1 and IECC thresholds.
ANSI/AMCA 208-18 · LiveFan acoustic calculator (VDI 3731)
Octave-band sound power from the aerodynamic duty point and fan geometry, plus the sound pressure level at a distance — inlet and outlet, A-weighted.
VDI 3731 · LiveFan operating point calculator
One duty point, every number that matters: velocities, density, motor load and efficiency, static/total/impeller efficiency, torque, SFP, FEI and VDI 3731 sound power.
All-in-one · LiveDuct pressure loss calculator
Velocity, Reynolds number, Darcy friction factor and total friction pressure loss for a straight duct run — Darcy-Weisbach + Colebrook-White, the physics behind ASHRAE Duct Design.
Darcy-Weisbach · LiveMotor efficiency calculator
Nominal efficiency for IE1–IE5 by rated power and pole count, per IEC 60034-30-1, plus input power and losses.
IEC 60034-30-1 · LiveFan array calculator
Ideal array performance (AMCA 270) plus the AMCA 201 System Effect Factor from wall clearance, partitions and fan-to-fan spacing — with a live layout diagram.
AMCA 201 & 270 · LiveAir compressibility calculator
The AMCA 210 compressibility coefficient Kp and corrected fan output power — the correction that starts to matter above 2.5 kPa.
AMCA 210 §7.8 · LiveSplitter silencer pressure drop calculator
Gap velocity, Reynolds number and total pressure loss through a rectangular splitter (baffle) silencer — auto-calculated gap width, contraction/friction/expansion losses.
Pressure drop, v1 · LiveHVAC unit converter
Flow, pressure, power, SFP, velocity, rotation, temperature, density, dimensions and area — metric and imperial, all on one page.
19 categories · LiveFan laws calculator
Scale flow, pressure and power between two operating conditions using the fan affinity laws — speed, diameter and density.
Affinity laws · LiveAir density calculator
Correct a duty point for temperature, altitude and humidity — actual density and the ratio versus standard conditions.
Barometric formula · LiveMollier (h-x) diagram calculator
Humidity ratio, enthalpy, dew point and wet-bulb temperature from dry-bulb temperature, relative humidity and altitude.
ASHRAE / WMO psychrometrics · LiveWhy we publish these
CloudAir builds fan selection software for manufacturers. Every program we deliver contains the same core arithmetic: efficiency and compliance checks, fan laws, acoustics, density corrections. None of that is proprietary — it comes from published standards and it should be easy to check.
So we opened the calculations up. Each tool implements one standard, states which one, links to the primary text, and produces a result you can share as a link. If a number here disagrees with your own sheet, the formulas are written out on the page so you can find out which of us is wrong.
What these tools deliberately do not do is select a fan. They evaluate one duty point against one criterion. The moment you need to run the same check across four hundred catalogue items, generate declared values for every published operating point and hand a customer a selection card in PDF — that is a selection program, and that is what we build.
Standards implemented
| Tool | Standard or regulation | Region |
|---|---|---|
| ErP 2026 compliance | Regulation (EU) 2024/1834, amended by (EU) 2025/2481 | European Union |
| Fan Energy Index | ANSI/AMCA 208-18; ASHRAE 90.1-2019, IECC 2021 | United States |
Want a calculator we have not built yet? Tell us which one and what it has to handle — we add tools based on what people actually ask for. Send us a note →