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Current calculator
Use Ohm's law to find current, voltage, resistance or power in a simple electrical circuit.
Current calculatorCurrent
Ohm's Law · I = V/R · Full Circuit Analysis
Ohm's Law: V = I × R | Power: P = V × I = I²R = V²/R
Electric current is the rate at which charge flows: how much charge passes a point each second. This calculator finds current from charge and time, or from voltage and resistance using Ohm's law, in whichever direction your problem gives the data.
How to use this calculator
- Choose the method: charge and time, or voltage and resistance.
- Enter the two values you know.
- Press calculate to see the current in amps.
Current is the same all round a simple loop
In a single-loop circuit the current is identical at every point, a fact beginners routinely doubt and examiners routinely test. What divides in parallel branches is current; what divides in series is voltage. Keeping those two straight resolves most early circuit confusion.
Frequently asked questions
What is the formula for electric current?
I = Q/t (charge divided by time). Through Ohm's law, also I = V/R (voltage divided by resistance).
What unit is current measured in?
The ampere (amp, A). One amp is one coulomb of charge flowing per second.
How much current is dangerous?
Even tens of milliamps through the body can be dangerous. Mains circuits carry far more, which is why circuit protection trips at currents well below what wiring can carry.