Ohm's Law Calculator
Use current and resistance to calculate voltage with V = IR. The result also shows power and conversion rows for milliamps, kilohms, millivolts, and milliwatts.
Formula
V = I x R
Units
A, mA, ohm, kohm
Also shows
P = VI
Live calculator
Current and resistance
Voltage
9.4 V
Current
0.02 A
Resistance
470 ohm
Power
0.188 W
| Voltage in mV | 9,400 mV |
|---|---|
| Current in mA | 20 mA |
| Resistance in kohm | 0.47 kohm |
| Power in mW | 188 mW |
Check basic circuit relationships without hiding units
Voltage from current and resistance
Calculate potential difference using the standard V = I x R relationship.
Power side check
See P = VI beside the voltage result so circuit examples can be cross-checked.
Common electrical units
Review mV, V, mA, A, ohm, kohm, mW, and W conversions in the same result.
Ohm's law formulas used on this page
Ohm's law relates voltage, current, and resistance for simple resistive circuit examples. Power is calculated from voltage and current.
Working formulas
Ohm's law
V = I x R
Voltage equals current multiplied by resistance.
Current form
I = V / R
Current can be solved when voltage and resistance are known.
Electrical power
P = V x I
Power is shown as a related circuit check.
Symbols
- V - voltage
- Electric potential difference in volts.
- I - current
- Electric current in amperes.
- R - resistance
- Electrical resistance in ohms.
- P - power
- Electrical power in watts.
Circuit output with conversion rows attached
Formula-first circuit checks
- The calculator normalizes current and resistance before calculating voltage.
- Power is displayed so the same inputs can be checked against P = VI.
- Conversion rows show mV, mA, kohm, and mW without changing the formula.
- Copy and print controls support worksheet answers and quick circuit notes.
Educational scope
- The page is written for physics and electronics arithmetic, not electrical safety advice.
- FAQ answers explain unit consistency, resistance meaning, and power checks.
- Related links connect Ohm's law to electrical power and the physics worksheets guide.
- The formula section defines each symbol before users rely on the result.
Ohm's law support for physics and electronics practice
Students
Check homework arithmetic while keeping SI conversions and formula variables visible.
Teachers
Create worksheet examples with formulas, units, and result summaries that print cleanly.
Formula reviewers
Audit values across common unit systems before comparing physics examples.
How it works in three quick steps.
Enter current
Type the circuit current and choose amperes or milliamperes.
Enter resistance
Type the resistance and choose ohms, kilohms, or megohms.
Read voltage and power
Use the voltage result and power row to check the circuit relationship.
Save or print an Ohm's law result
Copy the result
Copy the formula result and normalized SI values into notes, worksheets, or lesson drafts.
Print the calculator
Print inputs, outputs, formula notes, FAQ answers, and related physics links.
Compare examples
Change one variable at a time to see how unit conversions affect the final value.
Why Ohm's law pages need explicit unit conversion
Ohm's law is simple, but unit mistakes can make the answer unusable. Current may be given in milliamps, resistance in kilohms, and the expected answer in volts or millivolts. Toolarithm's Ohm's Law Calculator normalizes the inputs to amperes and ohms before applying V = I x R. The conversion rows are shown beside the result so the scale can be audited without repeating the calculation manually.
The page is deliberately scoped to education. It helps students and teachers check the mathematical relationship between current, resistance, voltage, and power. It does not replace electrical safety practice, component datasheets, circuit simulation, or professional engineering review. The related physics tools extend the same pattern into electrical power, energy, and motion formulas.
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