Free electronics calculators for resistors, capacitors and LEDs
Read a resistor, decode a capacitor or size an LED resistor in seconds. Free, no sign-up, and it works on your phone at the bench.
All tools
Resistor Color Code Calculator
Colors to ohms and ohms to colors, for 3, 4, 5 and 6-band resistors.
SMD Resistor Code Calculator
Decode 103, 4R7, 1002 and EIA-96 codes like 01C.
Capacitor Code Calculator
104, 473J, 4n7: the value in pF, nF and µF, with tolerance.
LED Resistor Calculator
The resistor value and wattage for one LED or a string in series.
Ohm's Law Calculator
Enter any two of V, I, R and P and get the other two.
Series and Parallel Resistor Calculator
Total resistance of any list of resistors, and standard pairs for any value.
Voltage Divider Calculator
Vout from two resistors, or the resistors for the Vout you need.
Popular resistor values
100 ΩBrown, Black, Brown, Gold
220 ΩRed, Red, Brown, Gold
330 ΩOrange, Orange, Brown, Gold
470 ΩYellow, Violet, Brown, Gold
1 kΩBrown, Black, Red, Gold
2.2 kΩRed, Red, Red, Gold
4.7 kΩYellow, Violet, Red, Gold
10 kΩBrown, Black, Orange, Gold
47 kΩYellow, Violet, Orange, Gold
100 kΩBrown, Black, Yellow, Gold
1 MΩBrown, Black, Green, Gold