Engineering calculators built for real fieldwork
Calculate Smarter. Work Faster.
Transformer sizing, motor current, cable sizing, DG sets, pump calculations, and practical maintenance guides — every formula shown, every assumption stated, every result instant.
Built and reviewed by engineers for field use
Electrical Calculators
Sizing and testing tools for transformers, cables, motors, protection devices, and power quality — built for field engineers and technicians.
Mechanical Calculators
Sizing and design tools for bearings, shafts, pumps, thermal systems, and compressed air — built for maintenance and design engineers.
Popular Mechanical Calculators
Bearing Life Calculator
Gear Ratio Calculator
Belt Length Calculator
Pump Head Calculator
Flywheel Energy Calculator
Advanced Boiler Efficiency Calculator
Shaft Torque Calculator
Beam Deflection Calculator
Compressor CFM Calculator
Tank Volume Calculator
Unit Converter Pro
Salary & Retirement Calculators
For salaried engineers and technicians — estimate your EPF retirement corpus and the gratuity you are entitled to after years of service.
Maintenance Guides
In-depth preventive and predictive maintenance guides for the electrical and mechanical equipment behind our calculators — checklists, test procedures, and troubleshooting written by working engineers.
Popular Maintenance Guides
DG Maintenance Guide
Transformer Maintenance Guide
Electric Motor Maintenance Guide
VFD Maintenance Guide
HT/LT Panel Maintenance Guide
Electrical Maintenance Guide
Air Compressor Maintenance Guide
Centrifugal Pump Maintenance Guide
Boiler Maintenance Guide
Bearing Lubrication Best Practices
Built by people who read nameplates for a living
Formulas shown, not hidden
Every calculator displays the exact formula used, so you can verify or learn it.
Standard-aligned values
Default constants follow common industry standards, not arbitrary rounding.
Works in the field
Fast on mobile data, no login walls — get your number in seconds on site.
Always free
Every calculator on this site is free, with no usage limits or paywalls.
Formula + assumptions + explanation
Each calculator shows the formula, the assumptions behind it, and a short explanation of the result.
Engineering decisions, financial context
The right technical choice should also hold up financially — that's why we cover cost, efficiency, and ROI calculators alongside the engineering ones.
Frequently Asked Questions
What is kVA, and how is it different from kW? +
kVA (kilovolt-amperes) is apparent power — the total power flowing in an AC circuit, including both the power doing useful work and the power lost to reactive loads like motor coils. kW (kilowatts) is real power, the portion that actually performs work. The two are related by power factor: kW = kVA × PF. A power factor of 1.0 means all apparent power is real power; most industrial loads run between 0.8 and 0.95.
Why is Power Factor important when sizing equipment? +
Power factor determines how much of the delivered apparent power (kVA) is actually converted into usable work (kW). A low power factor means transformers, generators, and cables must be rated larger to deliver the same real power, raising equipment cost and line losses. Many utilities also penalize industrial customers for poor power factor, which is why correction capacitors (APFC panels) are common on factory floors.
How do I choose the right transformer or DG size for my load? +
Add up your total connected load in kW, divide by the expected power factor to get kVA, then allow a design margin for future load growth and motor starting — the right margin depends on your load profile, motor starting method, and the applicable code or manufacturer guidance. Our Transformer Size and DG Size calculators let you apply a margin and round up to the nearest standard rating.
Are these calculators accurate enough for professional use? +
Yes — every formula used is the same standard formula taught in electrical and mechanical engineering coursework and referenced in field handbooks. That said, for safety-critical or code-compliance decisions, always verify results against your local electrical code and have them reviewed by a licensed engineer. The EPF and gratuity calculators follow the officially published Indian rules and are for educational planning purposes only — they do not constitute financial advice.
Does it work with my country's standards and currency? +
Mostly, yes. The engineering calculators use standard formulas that apply worldwide, and where a result depends on local values — such as supply voltage (for example 230/400V or 230/415V in many IEC countries, or 120/208V and 277/480V in North America) — you can enter the value that applies to your installation. The EPF and gratuity calculators follow Indian rules and are labeled as India-specific.
Can I use this on-site? +
Yes — every calculator is mobile-friendly, loads fast on limited data, and needs no login or account, so you can use it standing next to a panel or a pump skid, not just at a desk.
Free Engineering Calculators That Show the Formula
Reviewed under our Editorial Policy
Formula First, Every Time
Most engineering calculations rely on a few well-known formulas — the hard part is remembering the right constant and doing the math quickly. ElectroMechCalc shows the formula, the assumptions, and the result together, whether you are sizing a transformer, converting kVA to kW, or estimating motor full-load current. You can verify every number instead of trusting a black box.
Electrical and Mechanical Calculators
Electrical calculators cover transformer sizing, cable size and voltage drop, motor current, MCB/MCCB and fuse sizing, APFC capacitor sizing, DG, UPS, inverter, and solar sizing. Mechanical calculators cover bearing L10 life, gear ratio, pump head, belt length, shaft torque, beam deflection, and compressor CFM. Salary and retirement calculators help employees estimate their EPF corpus and gratuity payout. Practical maintenance guides for DG sets, transformers, motors, VFDs, pumps, and boilers complete the toolkit.
Who Uses These Tools
Engineering students check coursework, site electricians and technicians size cables and breakers on a phone, maintenance teams plan bearing and pump replacements, and facility managers plan transformer, generator, and backup-power capacity. No sign-up, no paywall — every calculator is free and loads fast even on mobile data.
Accuracy and Standards
Formulas and default values are referenced against IEC, IEEE, NEC, and BIS practice, and every default assumption is shown so you can change it. Results are estimates for learning and planning, not a substitute for professional engineering or financial advice — verify safety-critical or high-value decisions against your local code or a qualified professional. See our Disclaimer and Editorial Policy for details.
Feedback and New Calculators
Found an error or need a calculator that doesn't exist yet? Reach us through the Contact page — corrections are reviewed quickly. Learn who builds and reviews these tools on our About page.