Voltage Calculator
Calculate voltage, current, resistance, and power using Ohm's Law. Perfect for electricians, DIY projects, and LED installations.
⚡Enter Known Values
💡 Quick Presets
Power Consumption
Voltage
12.00 V
Current
2.00 A
All Calculated Values
⚠️ Safety Reminder
Always turn off power before working on electrical circuits. Use proper safety equipment and follow local electrical codes.
Understanding Ohm's Law
Ohm's Law is the fundamental principle of electrical circuits, describing the relationship between voltage, current, and resistance. This calculator helps you solve for any unknown value when you know the other two.
The Ohm's Law Formulas
V = I × R (Voltage = Current × Resistance)
I = V / R (Current = Voltage ÷ Resistance)
R = V / I (Resistance = Voltage ÷ Current)
P = V × I (Power = Voltage × Current)
Understanding the Units
- Voltage (V): Measured in Volts - the electrical "pressure"
- Current (I): Measured in Amps - the flow of electrons
- Resistance (R): Measured in Ohms (Ω) - opposition to current
- Power (P): Measured in Watts - energy consumption rate
Common Applications
- LED projects: Calculate resistor values for LED circuits
- Power supplies: Size your power supply correctly
- Wire sizing: Ensure wires can handle the current
- Energy costs: Calculate power consumption for devices
Frequently Asked Questions
What is Ohm's Law?
Ohm's Law states that voltage (V) equals current (I) times resistance (R), written as V = I × R. It's the fundamental relationship in electrical circuits.
How do I calculate voltage?
Voltage = Current × Resistance (V = I × R). If you know the current in amps and resistance in ohms, multiply them to get voltage in volts.
What voltage do I need for LED strips?
Most LED strips run on 12V or 24V DC. Check your LED strip specifications. 24V strips are better for longer runs as they have less voltage drop.
How do I calculate power consumption?
Power (watts) = Voltage × Current (P = V × I). For example, a 12V device drawing 2 amps uses 24 watts of power.