Science
Ohm's Law Calculator
Use this Ohm's law calculator for circuits where voltage, current, and resistance follow the basic linear relationship.
Choose the missing quantity; the calculator hides that field and solves it from the others.
Solved value
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- Voltage
- —
- Current
- —
- Resistance
- —
Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
Use this calculator with
Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
What the ohm's law calculator solves
Use this Ohm's law calculator for circuits where voltage, current, and resistance follow the basic linear relationship.
Formula
How to use it
- Choose the quantity you want to solve for.
- Enter the known values with consistent units.
- Check the rearranged formula, substitution, and warnings before using the result.
How to read the answer
For a fixed resistance, voltage rises in direct proportion to current.
Common mistakes and edge cases
- Use amps, not milliamps, unless you convert.
- This simple law assumes ohmic behavior.
- Resistance cannot be zero when solving for current.
Worked examples
Solve the main formula
Solved value
Voltage = 12 V
Reverse-solve a missing input
Solved value
Current = 1.5 A
Frequently asked questions
Can the ohm's law calculator solve for a missing variable?+
Yes. Use the solve-for control to hide the missing value, then enter the other known values with compatible units.
Why do the units matter?+
Formula calculators assume the entered values are already in matching units. Convert first when your measurements use mixed systems.
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Last updated: May 15, 2026