Ohm's Law Calculator & Resistor Colour Code
Calculate Voltage, Current, Resistance and Power instantly. Includes a live resistor colour band decoder with animated gold resistor graphic — pick colours and see the value update in real time.
✓ V = I × R
✓ P = V × I
✓ 4 & 5-band decoder
✓ Live resistor graphic
Ohm's Law Calculator
V = I × R
I = V ÷ R
R = V ÷ I
P = V × I
Cover the unknown to see the formula
Enter any 2 known values
V
Volts (V)
I
Amperes (A)
R
Ohms (Ω)
P
Watts (W)
All Ohm's Law formulas
| Find | Using V & I | Using V & R | Using I & R | Using P |
|---|---|---|---|---|
| V (Volts) | — | — | I × R | P ÷ I | √(P×R) |
| I (Amps) | V ÷ R (from VR) | V ÷ R | — | P ÷ V | √(P÷R) |
| R (Ohms) | V ÷ I | — | — | V²÷P | P÷I² |
| P (Watts) | V × I | V² ÷ R | I² × R | — |
Resistor Colour Code Decoder
Select resistor type
Resistance value
1 kΩ
±5% (Gold)
Range
950 Ω — 1,050 Ω
Value → Colour encoder
Colour code reference chart
| Colour | 1st/2nd digit | Multiplier | Tolerance | Temp. coeff. |
|---|
Common E12 resistor values — click to decode