EIA-96 Resistor Format Validator

EIA-96 resistor code: three characters for a 1% SMD resistor

Surface-mount resistors are too small for the old 3- or 4-digit value codes, so precision (1%, E96 series) parts use the compact EIA-96 marking: 2 digits + 1 letter, e.g. 39D. The two digits are not the resistance — they are an index (01–96) into a lookup table of the 96 standard 3-significant-figure values, and the letter is a multiplier.

How to decode it

• Digits → significand: the code 01 = 100, 02 = 102, 03 = 105 … 39 = 249 … 96 = 976. Each maps to one E96 base value.
• Letter → multiplier: Z=0.001, Y/R=0.01, X/S=0.1, A=1, B/H=10, C=100, D=1000, E=10000, F=100000.
• Resistance = significand × multiplier. Example: 39D = 249 × 1000 = 249 kΩ; 01A = 100 × 1 = 100 Ω; 68X = 499 × 0.1 = 49.9 Ω.

Why a lookup table instead of plain digits

The 4-digit SMD scheme (e.g. 2491 = 249 × 10) needs four characters; EIA-96 squeezes the same precision into three by replacing the 3-figure value with its 2-digit table position. That extra character saved on a 0402 package is the whole point.

Common pitfalls

• Reading the digits as the value: 39 is index 39 (= 249), not "39 ohms". This is the #1 mistake.
• Duplicate multiplier letters: R=Y=0.01 and S=X=0.1 — both spellings are valid.
• Index 00 is invalid: the table runs 01–96 only.
• Not the 3-digit SMD code: in the plain SMD scheme the last digit is a power-of-ten exponent — a different system entirely.

FAQ

Why is it called EIA-96? It encodes the 96 values of the E96 series (1% tolerance) standardized by the Electronic Industries Alliance.

What does 01A mean? Index 01 = 100, multiplier A = ×1, so 100 Ω.

Can I get the tolerance from the code? The EIA-96 code itself implies the E96 (1%) family; tighter tolerances use other series and markings.