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Electrical Calculators & Unit Converters
Electrical Calculators & Unit Converters
Electrical tools for electricians, engineers, students, pros and hobbyists.
Also accessible via: kwzap.com
From Ohm's Law to wire gauge and voltage drop, KiloWattCalculator.com brings together NEC-referenced (NFPA 70, National Electrical Code) electrical calculators and unit converters built for the job site, the classroom, and the workbench alike.
Who This Is For
KiloWattCalculator.com is a set of 28 electrical calculators and unit converters in three groups. The basic calculators handle everyday circuit and component math. The advanced calculators size wire, breakers, conduit, motors, transformers and panels. The converters move a value from one unit to another. The advanced calculators are NEC-referenced (NFPA 70, National Electrical Code).
Every calculator page explains how to use it and the math behind its result, and links to the tools that are usually needed alongside it. Results are for planning and checking work. They do not replace a licensed electrician or the code edition adopted where the work is installed.
Search for a tool by name, or browse the grid below. Read the full guide.
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These start with the core relationships between voltage, current, resistance and power. Ohm's Law solves any one of them from two known values. Amps to Watts and Watts to Amps apply that to single-phase and three-phase circuits, and each includes a table of typical equipment loads for comparison. Power Factor shows the difference between real and apparent power. Electrical Cost and the kWh Calculator turn wattage and hours of use into energy and an estimated bill at the rate you enter.
The rest of the group works with components. The Resistor Color Code decoder reads the bands on a resistor. The Series and Parallel Resistor calculator combines resistors into one equivalent value. The Voltage Divider sets an output voltage from two resistors. The Capacitor Calculator reads capacitor codes and combines capacitors. Capacitor Discharge shows how quickly a capacitor's voltage falls. The LED Resistor calculator sizes the resistor that keeps an LED within its rated current.
These are the sizing tools used when a circuit is being planned or checked. Wire Gauge and Voltage Drop confirm a conductor can carry the load over the length of the run. Breaker Sizing matches the overcurrent protection to that conductor. Conduit Fill checks that the conductors fit the raceway. Motor Starting Current and Transformer Sizing work from the equipment's nameplate ratings. Three-Phase Power covers the supply many of those loads run on. The Load Center calculator adds branch loads together to size a panel.
These calculators work best together. A wire size chosen without checking voltage drop, or a breaker chosen without the conductor, is a common mistake, and the related-tool links on each page lead to the next check. Before buying material or pulling a permit, confirm the equipment nameplate and the code edition your local authority has adopted.
Converters change the unit of a value, not the circuit. The group covers volts, amps, watts, kilowatts to horsepower, frequency, inductance, charge and resistance. The Ohms Converter is easy to confuse with Ohm's Law, but it only converts resistance between units. It also lists the E12, E24 and E96 standard resistor values from IEC 60063, so a converted number can be matched to a part you can buy.
Defaults are starting points. When a job differs, change the rate, length, power factor or ambient temperature to match it. Each result shows how it was calculated, so it can be checked against the nameplate and the applicable code before the work goes ahead.
For a circuit value or a component, open Basic Electrical Calculators. For a conductor, breaker, conduit, motor, transformer or panel, open Advanced Electrical Calculators. To change a unit, open Electrical Unit Converters. If a result looks wrong, tell us through the Contact page.