Free Engineering Calculators
Calculators for quick checks in electrical, mechanical and general engineering work, plus unit conversions you need every day.
Results are estimates for learning and sanity checks. Always verify against the codes, standards and professional calculations that apply to your project.
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Ohm's Law Calculator
Solve for voltage, current, resistance or power.
Resistor Color Code Calculator
Find resistance from 4, 5 or 6 color bands.
Unit Converter
Convert length, mass, pressure, energy and more.
Voltage Drop Calculator
Estimate voltage drop over a cable run.
Engineers: common questions
Are results suitable for final designs?
No. Use them for learning and quick checks. Final designs must be calculated and verified by a qualified engineer against the applicable codes.
Which units are supported?
Each calculator lists the units it accepts. Most support both metric and US customary units where that makes sense.