Example 1
What current at 230 W on 230 V? I = 1 A.
Current from Power and Voltage calculator
Type power P [W] and voltage U [V]. The calculator computes current I = P/U. 230 W at 230 V is 1 A. 60 W at 12 V is 5 A. Zero volts does not divide.
Power: P = U·I. Voltage from power: U = P/I.
Result
Power P (W) and Voltage U (V). The result shows up here.
How it works
Current from power and voltage is I = P/U, because P = U·I. At 230 W on 230 V you get 1 A. At 460 W on 230 V you get 2 A. At 60 W on 12 V you get 5 A. 2300 W on 230 V is 10 A. This is the P = U I rearrange, not P itself.
The form has two fields: P in watts and U in volts. The result is in amperes. Type 2.3 kW as 2300, not as 2.3. A comma and a period mean the same U: 3,7 and 3.7. 3.7 W on 3.7 V is 1 A.
U must not be zero, because you do not divide by zero. Typed 0 in U is rejected. Zero watts at nonzero U gives I = 0. Both fields need a number before 1 A appears.
P = U I is on the neighbouring page and computes watts from U and I. U = P/I is the sibling rearrange when you know P and I. R = U/I is on resistance from Ohm, not here.
Lower U at the same P gives larger I: 60 W on 12 V is 5 A, the same 60 W on 230 V is about 0.26 A. The calculator does not check a breaker.
Type 230 and 230, click Calculate, and check 1 A. Then 60 and 12: 5 A. The calculator divides P by U; it does not guess a power factor.
How to use
- In the first field enter P in watts, for example 230. 2.3 kW is 2300 W.
- In the second field enter U in volts, for example 230 or 12.
- Click Calculate. 230 W and 230 V give 1 A, because P = U I. 60 W and 12 V give 5 A.
- U = 0 is rejected. Zero in P at nonzero U gives I = 0. Both fields need a number.
- For P = U·I, open circuit power. Need U? Open U = P/I.
Formula
I = P / U
U ≠ 0.
I, P, and U from power
Current from power and voltage: I = P/U. 230 W on 230 V is 1 A. 60 W on 12 V is 5 A. U = 0 does not divide.
- I
- The unknown current [A]. 230 / 230 = 1 A. Not I = Q/t in this calculator.
- P
- Power [W]. 60 W at 12 V. This is P = U·I solved for I.
- U
- Voltage [V]. 12 or 230. Zero volts is rejected.
Real-life examples
Example 2
What current at 460 W on 230 V? I = 2 A.
Example 3
What current at 60 W on 12 V? I = 5 A.
Example 4
What USB current at 6 W on 5 V? I = 1.2 A.
Example 5
What current at 100 W on 50 V? I = 2 A.
Example 6
What kettle current at 2300 W on 230 V? I = 10 A.
Example 7
What LED current at 0.1 W on 5 V? I = 0.02 A.
Example 8
What current at 120 W on 24 V? I = 5 A.
Example 9
What current at 1000 W on 250 V? I = 4 A.
Example 10
What cell current at 3.7 W on 3.7 V? I = 1 A.
Ways to use this calculator
- You check 1 A from 230 W on 230 V.
- You compute 5 A from 60 W on 12 V.
Frequently asked questions
What is I at 230 W and 230 V?
Current is 1 A. From P = U·I you divide 230 W by 230 V and one ampere remains.
What about 60 W and 12 V?
You get 5 A. A 60 W lamp on a 12 V system draws five amperes, not the fraction you would see on 230 V mains.
Which units do I type?
Power P [W], voltage U [V]. Result I [A]. Type 2.3 kW as 2300 W, not as 2.3.
How is this different from P = U I?
Here you solve I = P/U. There you compute power from voltage and current. Same triple, different unknown.
Where is U = P/I?
On the voltage-from-power-and-current page. Here the unknown is I, there it is U.
Does a comma in 3,7 V work?
Yes. 3.7 W on 3.7 V gives 1 A. A comma and a period are the same decimal.
Do I type 2.3 kW as 2.3?
No. Field P wants P [W]. 2.3 kW is 2300 W, otherwise the current comes out a thousand times too small.
Where is R = U/I?
On the resistance-from-Ohm page. Here I comes from power and voltage, not from ohms.
What if U = 0?
The calculator refuses zero volts. I = P/U at zero voltage does not exist, because you do not divide by zero.
What about 460 W and 230 V?
Current is 2 A. That is twice the current of 230 W at the same voltage.
Knowledge sources
The formula is the school one. Units follow SI; NIST SP 330 and BIPM define the measures, not your result.
Page updated in 2026.