Guides
Engineering calculations, explained and ready to run
Each guide explains one calculation in plain words, with the formulas and the units, and ends in a live worksheet you can change, or copy into your own account.
Pipe pressure drop calculation with Darcy–WeisbachFriction factor, head loss and pressure drop for a given flow, with the Colebrook equation solved numerically.Fluids
Lead screw torque and motor sizingFrom the load to push and the screw lead to the torque, speed and power the motor must deliver.Mechanical
Bolt preload and tightening torqueProof load, preload, the torque–tension relation, and the margin left for the external load.Fasteners
Beam deflection and bending stressMoment of inertia, section modulus, and the deflection and stress formulas for the common load cases.Structures
Pump affinity laws: flow, head and power when speed or size changesWhat a change of speed or impeller diameter does to flow, head and power, and when the scaling holds.Fluids
Heat exchanger sizing with the LMTD methodDuty, log mean temperature difference, overall coefficient and the area that follows.Thermal
Snap-fit design: deflection, strain and mating forceStrain at the undercut, deflection force, and the push-on and pull-off forces from the angles and friction.Plastics
Lifting lug and padeye designDesign load, pin bearing and tear-out, bending at the base and the von Mises check, with DNV factors.Lifting
Natural frequency of a rectangular plateFlexural rigidity, mass per area and the frequency coefficient for the support condition.Vibration
Gear geometry: module, pitch diameter and bevel gear dimensionsFrom module and tooth count to every diameter, the centre distance, and the cone geometry of a bevel pair.Mechanical
Choosing a tool
Mathcad alternatives for engineering calculationsWhat a Mathcad replacement has to do, and how the candidates compare on notation, units, sharing and cost.Comparison
Engineering calculations in Excel: where it works and where it failsWhy most calculations live in spreadsheets, what goes wrong there, and when to move them out.Comparison
Run any of these with your own numbers
Open a guide, press "Try it live", change an input. A free account lets you keep a copy.