SMD Resistor Code Calculator
Decode surface-mount resistor markings — 3-digit (472), 4-digit (4701), R-notation (4R7) and EIA-96 codes (01C) — into ohms, or find the SMD codes for any resistance value.
How it works
3-digit: AB C → AB × 10^C Ω (472 = 47 × 10² = 4.7 kΩ) · 4-digit: ABC D → ABC × 10^D (4701 = 4.7 kΩ) · R marks the decimal point (4R7 = 4.7 Ω, R10 = 0.1 Ω) · EIA-96: two-digit index into the E96 table × letter multiplier (Z 0.001, Y/R 0.01, X/S 0.1, A 1, B/H 10, C 100, D 1k, E 10k, F 100k) · 0, 00, 000 = zero-ohm jumper
Chip resistors are too small for color bands, so they carry a short numeric code. Standard-tolerance parts (E24, ±5%) use three digits, precision parts (E96, ±1%) four digits, and on the tiny 0603 and smaller sizes precision values use the EIA-96 system: two digits that index the 96 standard values plus a letter for the multiplier. The letter R stands in for the decimal point on low values. The reverse mode shows which of the three styles can represent your value exactly.
Worked example
An SMD resistor marked 472 is a 3-digit code: 47 × 10² = 4,700 Ω, i.e. 4.7 kΩ, normally ±5%. The same value in the 4-digit style is 4701, and in EIA-96 there is no code for 4.70 kΩ because 470 is not an E96 value (the nearest are 4.64 kΩ = 65B and 4.75 kΩ = 66B).
Sources: IEC 60062:2016 Marking codes for resistors and capacitors · E series of preferred numbers — Wikipedia
Frequently asked questions
What does the R in an SMD code mean?
It marks the decimal point for values under 10 Ω (3-digit) or 100 Ω (4-digit): 4R7 = 4.7 Ω, R47 = 0.47 Ω, 10R0 = 10.0 Ω. In current-sense resistors you may also see an M for milliohms, e.g. 5M0 = 5 mΩ.
How do I read EIA-96 codes like 01C or 68X?
The two digits are an index into the E96 table (01 = 100, 02 = 102 … 96 = 976) and the letter is the multiplier: 01C = 100 × 100 = 10 kΩ, 68X = 499 × 0.1 = 49.9 Ω. They are used on 0603 and smaller 1% resistors where four digits will not fit.
What is a resistor marked 000 or 0?
A zero-ohm jumper: a link that lets a pick-and-place machine bridge two pads, often used as a configuration option or to cross a trace on a single-layer board.
Can I tell the tolerance from the code?
Only indirectly: 3-digit codes are normally E24 parts at ±5% (sometimes ±2%), and 4-digit or EIA-96 codes are E96 parts at ±1%. The exact tolerance is on the reel label or datasheet, not on the part.
Why is 4701 the same as 472?
Both mean 4.7 kΩ: 470 × 10¹ and 47 × 10². The extra digit simply allows values like 4.75 kΩ (4751) that a 3-digit code cannot express.
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This calculator is for educational purposes. Double-check important results before acting on them.