Ohm's Law defines the relationship between voltage (V), current (I), power (P) and resistance (R) in electrical circuits. It was discovered in 1827 by Georg Ohm (1789 – 1854), a German mathematician and physicist who, as a high school teacher, decided to study Alessandro Volta's new invention: the electromechanical cell (the precursor of the battery).
The relationships between the four important parameters of circuits are as follows:
  1. Voltage (V, in volts) calculations:
  2. Current (I, in amps) calculations:
  3. Power (P, in watts) calculations:
  4. Resistance (R, in Ω) calculations:
To use this calculator, enter a value for any two of the following: voltage, current, resistance, and power.
Engineering Calculator Disclaimer

Related GlobalSpec Product Areas

Potentiometers, rheostats and trimmers are three-terminal resistors that are used to measure or divide voltages, and to protect or control circuits. Search By Specification | Learn More about Potentiometers, Rheostats, and Trimmers

Digital Potentiometers (52 companies)

Digital potentiometers are three-terminal resistors with an adjustable center connection. To set the output resistance, a digital signal is sent through an electrical interface. Search By Specification | Learn More about Digital Potentiometers

Chip Resistors (232 companies)

Chip resistors are passive resistors with a form factor of an integrated circuit (IC) chip. Typically, they are manufactured using thin-film technology. Search By Specification | Learn More about Chip Resistors

Shunt Resistors (85 companies)

Shunts resistors are connected in parallel with an instrument or component to divert electrical current. They provide an alternate path for current in case of failure. Search By Specification | Learn More about Shunt Resistors

Resistor, capacitor networks (RC networks) are integrated circuits (ICs) that contain resistor-capacitor arrays in a single chip. Search By Specification | Learn More about Resistor, Capacitor Networks

Decade Boxes and Dividers (63 companies)

Decade boxes and dividers provide highly accurate and digitally variable standard values of resistance, capacitance, inductance, voltage and/or current for calibration, comparison and testing. Search By Specification | Learn More about Decade Boxes and Dividers

Resistance standards and decade boxes provide a highly accurate standard value of resistance for calibration and testing. Search By Specification | Learn More about Resistance Standards and Decades

Power Resistors (109 companies)

Power resistors are used in power generation and distribution, high-voltage applications, control systems, and other power system applications. They include load banks, grounding resistors, and dynamic braking resistors. Search By Specification | Learn More about Power Resistors

Current Sensing Resistors (69 companies)

Current sensing resistors convert the current flowing through it to a voltage drop. Monitoring or measuring this voltage drop allows the current through the resistor to be measured. Applications for current sensing resistors include power supplies, receptacles, and battery packs.  Search By Specification | Learn More about Current Sensing Resistors

Dynamic braking resistors (DBRs) produce braking torque and absorb the high amounts of energy generated by stopping electric motors. They are used in variable-speed drive systems such as elevators, cranes, and trains.  Search By Specification | Learn More about Dynamic Braking Resistors (DBRs)

Resistors (819 companies)

Resistors are electrical components that oppose the flow of either direct or alternating current. They are used to protect, operate, or control circuits. Search By Specification | Learn More about Resistors

Engineering Calculator Disclaimer

GlobalSpec, Inc. engineering calculators are free for individuals to use via this site under the terms and conditions set out under the Terms of Use of this web site and supplemented by this Engineering Calculator Disclaimer. These calculators are intended solely for general information and educational purposes, and are provided to help decrease the learning curve for those inexperienced in the engineering field and to give more experienced users additional reference tools.

The engineering calculators provided are not intended in any way as engineering advice or services, or as a solicitation for any engineering product or service. Any results from use of these calculators may not be applicable or accurate with regard to the individual circumstances, cannot be relied upon for anything, including, without limitation, engineering designs or decisions, and should not be the basis for any action or inaction on your part. Read Entire Disclaimer

Back to Top