Ohm's law and watts calculator
Calculate volts, amps, ohms and watts from any two known values.
For learning and low-voltage hobby work. In Australia, fixed mains wiring must be done by a licensed electrician.
How this calculator works
V = I × R and P = V × I. Rearrange these to find any value from two others.
Worked example: a 2,400 W kettle on Australia's 230 V supply draws 2,400 ÷ 230 = 10.4 A. That's why a standard 10 A power point is close to its limit with one kettle.
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