Ohm's law calculator
Enter two of V, I, and R. The third is computed. Nothing is assumed.
What this tool does
Ohm's law on this page is V = I × R. You enter any two of voltage in volts, current in amperes, and resistance in ohms. The missing one is computed. If you enter all three, the page checks whether they already satisfy the equation and says so, rather than overwriting one of them silently. Current is voltage divided by resistance, so a zero resistance when current is the unknown is refused. Resistance is voltage divided by current, so a zero current when resistance is the unknown is refused. One known value is not enough. The tool does not assume a mains voltage, a household current, or a component you did not name. The result is rounded to two decimal places. It is not a wire-size or a power-dissipation design.
How to use it
Leave the unknown box empty. Fill the other two. Submit. Read the label, which says whether the result is voltage, current, resistance, or a consistency check. If the message asks for two values, you left two boxes empty. Power is not on this form. If you need P = V × I, multiply the two quantities you already have, outside this check.
Worked example
2 amperes and 5 ohms give 10 volts, because V = I × R = 2 × 5. 230 volts and 10 ohms give 23 amperes. 12 volts and 0.5 amperes give 24 ohms. Entering 10 volts, 2 amperes, and 5 ohms reports that the three are consistent with V = I × R. Entering 10 volts, 2 amperes, and 4 ohms reports that they are not. The jobs link on this page searches HiringBuddy for published roles matching “engineer”. An empty list means nothing published matched. It is not a comment on the wider market. A signed-in candidate can save the attempt on their profile. Saving is not an application, and it does not show the attempt to an employer. Employers see people who apply to their own jobs.
Questions
- What if I know only the voltage?
- The tool refuses. It needs a second quantity. It will not assume a current.
- Can resistance be zero?
- Not when you are solving for current. Division by zero is refused.
- Does it calculate power?
- No. The relation on the page is V = I × R.