Voltage Drop Calculator

Voltage Drop Calculator is a clean, fast tool for estimating how much voltage a conductor loses along a run — completely offline. Pick the system, the wire and the load, and read the drop, the percentage and the voltage that actually reaches the load the moment you type. WHAT YOU CAN DO • Choose the system: DC, AC single-phase or AC three-phase • Choose the conductor: copper or aluminium • Pick a wire size from 14 AWG up to 4/0 AWG • Enter one-way length, load current and source voltage • See the voltage drop in volts, the drop percentage, and the voltage at the load • Get a guideline flag when the drop passes the common 3% branch or 5% total limits HOW IT WORKS Voltage drop is calculated as factor x length x current x resistance per length. The factor is 2 for DC and single-phase AC, and the square root of 3 for balanced three-phase. Resistance comes from standard AWG values for copper, scaled by about 1.6 for aluminium. WORKED EXAMPLES An Examples tab shows ready-made scenarios — a 120 V lighting branch, a 240 V appliance run, a 12 V DC solar feeder and a 480 V three-phase motor — each with its calculated result, so you can see how gauge, length and current change the outcome. LEARN AS YOU GO A built-in Learn tab explains, in plain language, what voltage drop is, why it matters for lights, motors and electronics, and how wire gauge, run length and current each affect it. IMPORTANT: GENERAL ESTIMATE ONLY The results are general estimates for planning and education. They use standard resistance values at a reference temperature and do not account for every real-world factor such as temperature, bundling, terminations or power factor. They are not a substitute for professional design. Always consult a licensed electrician and follow your local electrical code before making any wiring decision. PRIVACY The app collects no personal data and works fully offline — your numbers never leave your device. Ads are served by Google AdMob, which may use an advertising identifier as described in Google's policies. Light and dark themes, a tiny download, and no clutter. Download Voltage Drop Calculator and size your conductors with confidence.