Ohm’s Law Calculator
Calculate voltage, current, resistance, and power – enter any two values
Quick Examples
Enter Any Two Values
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Voltage (V)
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Current (A)
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Resistance (Ω)
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Power (W)
Wire Gauge Reference
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Energy Over Time
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Ohm’s Law Formulas
V = I × RVoltageI = V / RCurrentR = V / IResistanceP = V × IPowerP = I² × RPowerP = V² / RPowerCommon References
USB 2.0
5V, 0.5A (2.5W)
USB-C PD
5-20V, up to 5A (100W)
US Outlet
120V, 15-20A
EU Outlet
230V, 16A
Car Battery
12V DC
Tesla Supercharger
480V, 600A (250kW)
AA Battery
1.5V
Human Safe Current
<10mA (painful >1mA)
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