How it works
On a 4-band resistor the first two bands are digits, the third is a multiplier and the fourth is tolerance. Precision 5-band resistors add a third digit band, and 6-band resistors add a temperature coefficient band at the end.
Read the resistor with the tolerance band (usually gold or silver, often spaced slightly apart) on the right. Digits use black = 0 through white = 9; the multiplier band means ×10 to the power of that digit, with gold = ×0.1 and silver = ×0.01.
4-band: R = (10·d1 + d2) × 10^m
5/6-band: R = (100·d1 + 10·d2 + d3) × 10^mWorked example
Yellow, violet, red, gold is 4 and 7 followed by a ×100 multiplier: 47 × 100 = 4,700 Ω (4.7 kΩ) with ±5% tolerance, so the actual value can be anywhere from 4,465 Ω to 4,935 Ω.