Frequently asked questions
1. What are the most useful engineering calculators?
Torque, gear ratio, motor RPM, force, pressure and Ohm's law cover most day-to-day mechanical and electrical back-of-envelope checks; voltage drop, power factor and the five construction take-off calculators extend that to wiring jobs and material ordering.
2. Do these calculators support both metric and imperial units?
Yes. Most calculators work in SI units or imperial units and show converted results, so you can cross-check drawings and datasheets from either convention. Construction calculators default to the feet-and-inches convention US suppliers actually price in.
3. Are the formulas simplified or the real engineering versions?
They are the standard engineering formulas — the same ones in Shigley's, the Machinery's Handbook, the NEC guidelines and first-year physics courses. Where a real-world correction matters (efficiency, waste factors, temperature), the calculator notes it and the article explains how to apply it.
4. Can I use these calculators for coursework and professional estimates?
Yes. Each page shows the formula, the substituted values and the intermediate steps, which makes them suitable for checking homework, verifying supplier quotes or estimating materials. For safety-critical design, always verify against a full analysis.