Ohm's Law Calculator

Calculate voltage, current, resistance, and power with our comprehensive electrical calculator

⚡ Calculator

V R I
Voltage
0 V
Current
0 A
Resistance
0 Ω
Power
0 W
V = I × R

📊 Common Electrical Values

Component Typical Values
LED 1.8-3.3V, 10-20mA
USB Port 5V, 0.5-2.4A
Wall Outlet (US) 120V, 15-20A
Car Battery 12V, 40-100A

🔌 Unit Conversions

Unit Conversion
1 kV 1,000 V
1 A 1,000 mA
1 mA 1,000 μA
1 MΩ 1,000,000 Ω

Common Examples

💡 LED Circuit
9V battery, 470Ω resistor
🔌 USB Charging
5V, 2A output
🏠 Household Bulb
120V, 60W bulb

🔧 Other Helpful Electrical Calculators You Might Need

Hey there! If you're working with electronics or electrical stuff, these other tools might come in handy for your projects - I use them myself sometimes when the ohm law ain't enough for what I'm trying to figure out.

📏 Wire Size Calculator
Figuring out what gauge wire you need for your project can be tricky, this helps make sure you don't overload anything
🔋 Voltage Divider Calculator
Super useful when you need to get a specific voltage from two resistors, saves you from doing the math manually
🔋 Battery Life Calculator
Wanna know how long your battery will last? This tells you based on the current draw and capacity
💡 LED Resistor Calculator
Takes the guesswork out of picking the right resistor for your LEDs so you don't burn them out accidentally

Frequently Asked Questions

What is Ohm's Law and its formula?

Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. The formula is V = I × R, where V is voltage (volts), I is current (amperes), and R is resistance (ohms).

How do I calculate power using Ohm's Law?

Power can be calculated using three formulas: P = V × I (voltage times current), P = I² × R (current squared times resistance), or P = V² / R (voltage squared divided by resistance). Our calculator automatically computes power along with other values.

What are the units used in Ohm's Law calculations?

The standard units are: Voltage (V) in Volts, Current (I) in Amperes (Amps), Resistance (R) in Ohms (Ω), and Power (P) in Watts (W). Our calculator supports metric prefixes like milli, kilo, and mega.

Can Ohm's Law be applied to AC circuits?

Basic Ohm's Law applies directly to DC circuits and purely resistive AC circuits. For AC circuits with inductance or capacitance, you need to consider impedance (Z) instead of resistance (R), and the calculations become more complex.

What is the relationship between watts, volts, and amps?

The relationship is defined by the power formula: Watts = Volts × Amps (P = V × I). For example, a device using 2 amps at 120 volts consumes 240 watts of power.

Why is my calculated value showing as infinity or NaN?

This typically happens when you enter zero for resistance while calculating current (I = V/R), which would result in division by zero. Make sure all values are greater than zero and within reasonable ranges.

What safety considerations should I keep in mind when working with electricity?

Always prioritize safety: turn off power before working on circuits, use appropriate protective equipment, verify calculations before applying them, never exceed component ratings, and consult qualified electricians for high-voltage or complex installations.