Engineering Calculators

V=IR — solve for any variable

Decode 4-band resistor colors

Electrical power, current, voltage

Find hypotenuse or missing side

Calculate resistor value to safely drive an LED

Output voltage and current from a resistor voltage divider

Estimate how long a battery will last for a device

Minimum trace width for a given current (IPC-2221)

Convert between dB and power/voltage ratios

Dipole, quarter-wave and Yagi antenna lengths

Torque, force, arm length and angular conversions

Inverter VA rating and battery capacity for your load

Air conditioner tonnage needed for your room size

Simply supported beam — max bending moment and deflection

Flow rate, velocity and friction loss in pipes

Power, current and voltage for 3-phase electrical systems

Turns ratio, voltage and current for transformer design

LMTD, heat transfer rate and required area

Reynolds number, velocity and pressure drop in pipes

Hooke's law — force, energy and frequency of springs

Speed, torque and power through gear trains

Calculate the required electric motor horsepower and kW from load torque and speed

Decode 4-band resistor color bands into Ohm value and tolerance percentage