Resistor Code & Band Calculator

Resistor Decoders help identify the nominal resistance and tolerance of color-banded through-hole resistors and surface-mount (SMD) chips.

Marking Codes:

• 4-Band: Digit 1, Digit 2, Multiplier, Tolerance
• 5-Band: Digit 1, Digit 2, Digit 3, Multiplier, Tolerance
• SMD: 3-digit (10% standard), 4-digit (1% precision), or EIA-96 codes

Usage: Select the color bands for through-hole resistors or enter the alphanumeric SMD code to decode the resistance immediately.

When you need it: Reading a colour-banded resistor, or going the other way to find the bands and the nearest standard value — for 3-, 4-, 5- and 6-band parts as well as SMD number codes.

Worked example: Brown-black-red-gold = 10 × 100 = 1 kΩ, ±5%. A 4-band's third band is the multiplier; a 5-band adds a third significant digit. An SMD marking 472 means 47 × 10² = 4.7 kΩ.

Tips & gotchas:

• Gold and silver multiplier bands mean ÷10 and ÷100 — that's how sub-ohm values are coded.
• The tolerance band (gold ±5%, brown ±1%) sits slightly apart, which tells you which end to read from.
• Snap the result to the nearest E-series standard value; odd values usually mean you misread a band.
• On SMD parts an R marks the decimal point — 4R7 is 4.7 Ω, not 47.