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Ohm's Law Calculator

Fill in any two values and the third is calculated automatically. Power is always computed as a bonus.

V?I?R?
VVoltage (V)
ICurrent (I)
RResistance (R)

📐 Ohm's Law Formulas

Voltage
V = I × R
Current
I = V / R
Resistance
R = V / I
Power
P = V × I = I² × R = V² / R

Quick Examples

🧠 Real-world intuition

  • 💧 V = water pressure (volts)
  • 🌊 I = water flow rate (amperes)
  • 🪠 R = pipe narrowness (ohms)
  • P = total power (watts = how much heat is generated)

Double the voltage → double the current.
Double the resistance → halve the current.