Engineering tools and references
Source-backed calculators, formula references, tables, and unit tools built for mechanical engineers.
Fluids & Piping Calculators
Reynolds Number
Screen circular pipe flow regime from average velocity, inside diameter, and viscosity.
Pipe Velocity
Calculate average velocity in a full circular pipe from volumetric flow rate and inside diameter.
Darcy-Weisbach Pressure Loss
Calculate straight-pipe major pressure loss and head loss from a user-supplied Darcy friction factor.
Pump Head From Pressure
Convert a pump pressure rise or differential pressure into equivalent liquid head.
Volumetric Flow Conversion
Convert common SI, U.S. liquid, and cubic-foot-per-minute volumetric flow units.
Statistics & Sample Size
Confidence Interval (Mean)
Compute a one-sample confidence interval for a continuous mean from summary statistics.
Confidence Interval (Proportion)
Compute a Wilson score confidence interval for a binary proportion or nonconformance rate.
Sample Size (Mean)
Estimate the number of independent measurements needed to bound a continuous mean by a target margin of error.
Sample Size (Proportion)
Estimate the number of binary observations needed to bound a proportion or nonconformance rate by a target margin of error.
Margin of Error Guide
Understand margin of error as confidence-interval half-width and how it changes with sample size, variability, and confidence level.