Four-digit SMD resistor markings use one more significant digit than the common three-digit pattern. This guide answers the focused question of how to read 1002 and 4701 without treating the printed characters as an ordinary four-digit ohm value. Use the SMD Resistor Code Decoder for the complete mark, then use the product series datasheet to confirm that the marking belongs to the intended component family.
Read three significant digits first
In the supported four-digit rule, the first three characters are the significant digits and the fourth character is the multiplier digit. Keep the four printed characters together when entering the code. The last digit is not another significant digit, so a four-digit mark such as 1002 is not read as 1,002 ohms and 4701 is not read as 4,701 ohms.
Worked example: 1002
For 1002, the significant digits are 100 and the final digit is 2. The supported calculation is 100 x 10^2 ohms, which gives 10 kohm. The extra zero in the printed mark is part of the three-digit significant value. It is not evidence that the component has a 1,002 ohm resistance.
Worked example: 4701
For 4701, the significant digits are 470 and the final digit is 1. The supported calculation is 470 x 10^1 ohms, which gives 4.7 kohm. The last 1 controls the power-of-ten step; it is not appended to the value digits.
Compare the two supported readings
| Printed mark | Significant digits | Multiplier digit | Decoded result |
|---|---|---|---|
| 1002 | 100 | 2 | 10 kohm |
| 4701 | 470 | 1 | 4.7 kohm |
The table shows why the final character must be kept in its multiplier role. A short marking such as 103 belongs to the three-digit guide and follows a different significant-digit count, even when the final digit also acts as the multiplier position.
Do not infer the rest of the specification
The four-digit code gives a decoded resistance candidate within the supported rule. It does not identify tolerance, package size, power, voltage, temperature coefficient, pulse capability, current capability, or manufacturer series. A product series datasheet is the controlling source for those specifications. If the code is printed faintly, partly hidden, or associated with an unknown package, record the uncertainty instead of presenting the numeric result as a complete part number.
Choose the matching guide
Use the 3-Digit SMD Resistor Code guide when only three digits are printed. If the mark contains R, use the SMD R Decimal Notation guide because R marks a decimal position in the supported examples. For 0, 00, 000, or 0000, use the Zero-Ohm SMD Marking guide.
Source and limits
This page covers only the supported four-digit printed SMD marking rule represented by the site decoder. The worked examples are limited to 1002 and 4701; they demonstrate the code positions and do not replace product identification.
- Use the SMD Resistor Code Decoder for the printed mark, then verify tolerance, specification, package, and manufacturer series in the product series datasheet.
- Do not treat four-digit SMD text as a through-hole color-band code or use a color-band calculator as the SMD tool.
- A printed marking alone is not enough for a safety, procurement, compliance, or replacement decision.