Ohm’s Law Calculator (Voltage, Current, Resistance & Power Calculator)
Instantly calculate Voltage (V), Current (I), Resistance (Ω), and Power (W) using Ohm’s Law and Watt’s Law. Perfect for electrical engineers, students, electricians, and circuit designers.
Ohm's & Watt's Law Triangles
Free Ohm's Law Calculator & Watt's Law Calculator
Whether you are an electrical engineering student, a licensed electrician, or a DIY hobbyist, solving electrical circuits requires precision. Our professional Ohm's Law Calculator seamlessly integrates Watt's Law, allowing you to quickly determine Voltage (V), Current (I), Resistance (R), and Power (P) by simply entering any two known variables.
How to Use the Calculator
- Select Your Knowns: Use the dropdown menu at the top to select the two electrical parameters you already know.
- Enter Your Values: Type your numbers or use the interactive sliders.
- Adjust Your Units: Use the adjacent dropdowns to define your metric prefixes. The calculator flawlessly handles milli (m), micro (µ), kilo (k), and Mega (M) conversions instantly.
- View Instant Results: Calculated answers are highlighted in green, complete with primary and secondary scaled units. The step-by-step formula breakdown is shown automatically below the results.
Example Calculations
If a circuit has Voltage = 12V and Current = 2A:
• Resistance: R = V / I ➔ 12 / 2 ➔ 6.00 Ω
• Power: P = V × I ➔ 12 × 2 ➔ 24.00 W
What is Ohm’s Law?
Ohm’s Law states that the current flowing through a conductor is directly proportional to the voltage and inversely proportional to the resistance. Formula: V = I × R. This law is fundamental to electrical engineering and is widely used in circuit analysis, electronics design, and troubleshooting.
Watt’s Law
Watt’s Law defines the relationship between power, voltage, and current. Formula: P = V × I. This is used to calculate total electrical power consumption in circuits and devices, determining how much energy a component uses or generates as heat.
Common Uses of Ohm’s Law
- Electrical circuit design and PCB routing
- Battery life and load calculations
- Sizing the correct LED current-limiting resistor
- Estimating power consumption for household appliances
- Electrical troubleshooting and multimeter diagnostics