The colors
| Black | 0 |
| Brown | 1 |
| Red | 2 |
| Orange | 3 |
| Yellow | 4 |
| Green | 5 |
| Blue | 6 |
| Violet | 7 |
| Grey | 8 |
| White | 9 |
As a multiplier, gold means × 0.1 and silver × 0.01. As a tolerance, gold is ±5%, silver ±10%, brown ±1% and red ±2%.
4-band resistors
Two digits, a multiplier and a tolerance. Brown, black, red, gold is 1, 0, × 100 = 1 kΩ ±5%. Yellow, violet, orange, gold is 47 × 1,000 = 47 kΩ ±5%.
5 and 6 bands
Precision resistors have three digits before the multiplier. Brown, black, black, brown, brown is 100 × 10 = 1 kΩ ±1%. A sixth band gives the temperature coefficient, how much the value drifts with heat, in ppm/K.
Which end first
The tolerance band is usually gold or silver and set a little apart from the others. Hold the resistor with it on the right. If you are unsure, check with a multimeter.
Calculator
Pick the bands in the Resistor Color Code Calculator to read the value. To work out what value you need, use the Ohm's Law Calculator or the LED Resistor Calculator.