Starting Capacitor Calculator

Starting Capacitor for 3-Phase to Single-Phase Conversion

Do you have a three-phase motor but only a single-phase power supply at home or in your workshop? You’re not alone — many people face this challenge when trying to run equipment like water pumps, compressors, or woodworking machines without access to industrial power.

The solution is simple: a starting capacitor. By adding the right capacitor, you can successfully start and run a three-phase motor on a single-phase line. Choosing the correct capacitor value, however, is critical. If it’s too small, your motor won’t start. If it’s too large, it may overheat or get damaged.

That’s why this page provides you with an easy-to-use capacitor calculator. Just enter your motor’s power (kW) and voltage, and the tool will instantly estimate the ideal capacitor size for a smooth and safe start. This saves you time, money, and guesswork.

After calculating, you can also directly order a reliable power factor/starting capacitor from our recommended supplier on AliExpress.

The capacitor sizing formula used here is an approximation commonly applied when running a 3-phase motor on single-phase power. It is expressed as: C (µF) = P (W) ÷ (2π × f × V² × k). In this equation, P is the motor power in watts, f is the supply frequency in hertz, V is the operating voltage, and k is a constant based on motor characteristics (typically between 2 and 3). This formula helps estimate the capacitor size needed to ensure proper motor performance and reduce starting difficulties.