Ohm
Voltage, current, resistance, and power from any two values
LED Resistor Calculator
Series resistor for LEDs with forward voltage and current
Gear Ratio Calculator
Gear ratio, output speed, and torque from teeth counts
Battery Life Calculator
Battery runtime with capacity, consumption, and efficiency
Amps to kW Calculator
Convert amps to kilowatts for single-phase and three-phase circuits, including power factor and kVA. Also converts kW back to amps.
Pipe Friction Loss Calculator
Estimate pressure drop in pipes using the Hazen-Williams equation. Enter flow rate, pipe size, length, and pipe material to get psi loss and velocity.
Gas Strut Calculator
Size gas springs for lids, hatches, and cabinet doors. Enter weight, dimensions, and mounting points to find the required strut force.
kW to Amps Calculator
Convert kilowatts to amps for single-phase and three-phase circuits with power factor. Size breakers and cables from your load in kW.
Lumens to Watts Calculator
Convert lumens to watts for LED, CFL, halogen, and incandescent bulbs. Find out how much power a given brightness needs and compare bulb types.
Power Factor Calculator
Calculate power factor from kW, kVA, voltage, and current. See real vs apparent power, reactive power, and whether you need correction.
Viscosity Index Calculator
Calculate the viscosity index (VI) of an oil from its kinematic viscosity at 40°C and 100°C using the ASTM D2270 method.
Watts to Lumens Calculator
Convert watts to lumens for LED, CFL, halogen, and incandescent bulbs. See how bright a given wattage will be with different bulb types.
Feeds and Speeds Calculator (CNC)
Calculate spindle speed (RPM), feed rate and material removal rate for CNC milling and drilling from cutting speed, tool diameter, flutes and chip load — in metric or imperial units.