About the Ohms Law Solver
What is the Ohms Law Solver?
This ohms law solver handles every combination: give it any two of voltage, current, resistance and power, and it finds the other two using the right formula from the Ohm's law "wheel".
Leave the two unknowns at zero. For example, a 1,000 W heater on 230 V draws 4.35 A and has a resistance of 52.9 Ω.
How to use the Ohms Law Solver
- Voltage (V, 0 if unknown) (sample: 230)
- Current (A, 0 if unknown) (sample: 0)
- Resistance (Ω, 0 if unknown) (sample: 0)
- Power (W, 0 if unknown) (sample: 1,000)
- Press Solve V, I, R and P (results also refresh as you type). The result card shows the Current, along with Voltage, Resistance, Power and Formulas used.
Formula used
P = V × I = I² × R = V² ÷ R
- V = I × R = Ohm's law
- P = V × I = electrical power
Combining the two laws gives 12 formulas – the calculator picks the right one automatically.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Voltage (V, 0 if unknown) | 230 |
| Current (A, 0 if unknown) | 0 |
| Resistance (Ω, 0 if unknown) | 0 |
| Power (W, 0 if unknown) | 1,000 |
| Result | Value |
|---|---|
| Current | 4.3478 A |
| Voltage | 230 V |
| Resistance | 52.9 Ω |
| Power | 1,000 W |
| Formulas used | I = P ÷ V, R = V² ÷ P |
Tips for using the Ohms Law Solver
- Use it to find the current rating needed for a fuse or MCB from an appliance's wattage.
- Resistance of heating elements rises when hot, so cold resistance readings are lower.