Engineering calculators
Free, right in your browser, and every result shows its work — the equation, the numbers substituted in, and each intermediate value, laid out the way a worked PE solution is. Each one names where its equation lives in the NCEES Reference Handbook and how the topic is tested.
Exam utilities
The moves you make on every exam: reading between table rows and moving money through time.
Psychrometrics and air
Moist-air properties and the standard-air relations behind HVAC load and airflow problems.
- Psychrometric calculatorEvery moist-air property from dry bulb plus one more, at any altitude, from the ASHRAE equations.
- Dew point calculatorDew point from dry bulb and relative humidity — the surface temperature where moisture starts to condense.
- Wet bulb calculatorThermodynamic wet-bulb temperature from dry bulb and relative humidity, at any altitude.
- Relative humidity calculatorRelative humidity from dry bulb plus dew point or wet bulb.
- CFM calculatorAirflow from a heat load or from air changes per hour — standard-air factors, corrected for altitude.
Pipe and open-channel flow
Reynolds number, friction factor, pipe head loss and open-channel flow.
- Reynolds number calculatorReynolds number and flow regime for pipe flow, with water properties at any temperature built in.
- Friction factor calculator (Colebrook / Moody)The Darcy friction factor from Reynolds number and relative roughness — the Colebrook equation the Moody diagram is drawn from.
- Pipe head loss calculator (Darcy–Weisbach)Head loss and pressure drop in a full pipe from flow, size, length and roughness — Darcy–Weisbach with Colebrook.
- Hazen–Williams calculatorHead loss or flow for water in a full pipe, from the Hazen–Williams C factor.
- Manning's equation calculatorOpen-channel flow from depth, or normal depth from flow — rectangular, trapezoidal and partly full pipes.
Practice these on exam-real problems.
Problems built like the real exam, each with a worked solution. Available today for PE Mechanical, PE Electrical: Power and PE Civil: Water Resources & Environmental. The whole practice bank is free with an account.
Start practicing freeOn exam day, it's your own calculator.
These are for studying and for work. In the exam you'll use one NCEES-approved handheld model. See which models are allowed.