SMD Resistor Code Calculator
This surface-mount resistor code calculator decodes the three-digit number printed on the top of a chip resistor and returns the resistance in ohms and kilohms. Surface-mount resistors are too small for color bands, so they carry a compact numeric code: the first two digits are the significant figures and the third digit is the multiplier, the number of zeros to append. A resistor marked 473 therefore reads as 47 followed by three zeros, which is 47,000 ohms, or 47 kilohms. The scheme follows the standard significant-digit and power-of-ten convention that the US National Institute of Standards and Technology and component data sheets use for resistance. Enter the three digits of the code and the calculator combines the first two as a two-digit number multiplied by ten raised to the third digit, then expresses the result in both ohms and kilohms. Use it to read an unmarked board, verify a salvaged part, or check a substitution. The same digit-plus-multiplier logic from the resistor color code applies here in printed form, so the value reads straight off in ohms. Every figure is computed deterministically from the three-digit code formula shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step yourself.
The first two digits are the value and the third is the number of zeros: code 473 means 47 followed by 3 zeros, which is 47,000 ohms, equal to 47.00 kilohms. The code reads directly in ohms.
SMD resistor code formula
R = ( d1 x 10 + d2 ) x 10 ^ d3 ohms
d1 = first digit, d2 = second digit
d3 = third digit (number of zeros to append)
1,000 ohms = 1 kilohm
The first two printed digits form a two-digit number, and the third digit gives the power of ten by which to multiply, that is the number of trailing zeros. The result is the resistance in ohms, easily scaled to kilohms by dividing by a thousand.
Worked example
Decode a surface-mount resistor printed with the code 473.
- two-digit value = 4 x 10 + 7 = 47
- multiplier = 10 ^ 3 = 1,000
- R = 47 x 1,000 = 47,000 ohms
- 47,000 ohms = 47.00 kilohms
Code 473 is 47,000 ohms, which is 47.00 kilohms. These are the calculator's default inputs, so the result above matches the widget exactly.
Common SMD resistor codes
A few frequently seen three-digit codes and their resistance values.
| Code | Ohms | Common form |
|---|---|---|
| 100 | 10 | 10 ohm |
| 221 | 220 | 220 ohm |
| 103 | 10,000 | 10 kohm |
| 473 | 47,000 | 47 kohm |
| 105 | 1,000,000 | 1 Mohm |
Units and measurement reference: US National Institute of Standards and Technology (NIST).
SMD Resistor Code Calculator: frequently asked questions
How does the three-digit SMD code work?
The first two digits are the significant figures of the resistance and the third digit is the multiplier, meaning the number of zeros to add. So 473 is 47 with three zeros, giving 47,000 ohms. This calculator combines the digits exactly that way and reports the result in ohms and kilohms.
What does an R in the code mean?
An R marks the decimal point for resistances below 10 ohms. For example 4R7 is 4.7 ohms and R47 is 0.47 ohm. This decoder handles the standard three-digit whole-multiplier codes; for an R-style code, read the R as a decimal point directly in ohms.
What is the four-digit code variant?
Precision resistors often use a four-digit code where the first three digits are significant figures and the fourth is the multiplier. For instance 4702 is 470 with two zeros, giving 47,000 ohms. The three-digit code in this tool is the more common form on general-purpose chip resistors.
What about the EIA-96 code?
Very small 1 percent resistors sometimes use the EIA-96 system, a two-digit number followed by a letter, where the digits index a lookup table of values and the letter is the multiplier. That is a separate scheme from the three-digit code decoded here, which uses straightforward significant digits and a power-of-ten multiplier.
Does a code of 000 mean anything?
A marking of 000 or 0 denotes a zero-ohm resistor, used as a jumper or link on a circuit board. It has essentially no resistance and simply connects two points. Entering all zeros in this calculator returns 0 ohms, which is the correct reading for such a link.
Official sources
- Electrical units and measurement reference: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.