SMD Resistor Code Calculator
Enter the code printed on your surface-mount resistor to find its resistance value.
3-digit codes (e.g. 103) and 4-digit codes (e.g. 4702) are both supported, as is an R in place of a decimal point (e.g. 4R7 = 4.7 Ω).
How SMD resistor codes work
On a 3-digit code, the first two digits are significant figures and the third digit is the power-of-ten multiplier — so 103 means 10 × 10³ = 10,000 Ω (10 kΩ). On a 4-digit code (used for tighter-tolerance resistors), the first three digits are significant and the fourth is the multiplier — so 4702 means 470 × 10² = 47,000 Ω (47 kΩ).
For resistances under 10 Ω, where a multiplier of 10⁰ isn't enough precision, manufacturers use R in place of a decimal point instead — so 4R7 means 4.7 Ω, and R47 means 0.47 Ω.
Frequently asked questions
How do I read a 3-digit SMD code?
The first two digits are the significant figures, and the third digit tells you how many zeros to add (or more precisely, the power of 10 to multiply by). 220 means 22 × 10⁰ = 22 Ω.
What's the difference between a 3-digit and 4-digit code?
A 4-digit code has one more significant figure, giving finer precision (typically used for 1% tolerance resistors), while 3-digit codes are more common on standard 5% tolerance resistors.
What does the letter R mean in a code like 4R7?
R stands in for the decimal point, used when the value is small enough that a multiplier alone couldn't express it precisely — 4R7 reads as "4.7" ohms.