Decode 4-band and 5-band resistor values from color code bands
Electrical Calculator
Resistor colour code — Quick answer
A resistor colour code calculator decodes the coloured bands on a resistor body into a resistance value and tolerance. Standard codes use 4, 5, or 6 bands.
4-band: value = (D1 × 10 + D2) × 10M, tolerance = band 4 5/6-band: value = (D1 × 100 + D2 × 10 + D3) × 10M
D1...D3 — significant digits from band colours
M — multiplier (decimal exponent)
tolerance — ± % (gold 5%, silver 10%, brown 1%, red 2%)
Used for: Hobbyist electronics, PCB repair, breadboard prototyping, EE classroom teaching, identifying through-hole resistor values.
🔴 Resistor Color Code Calculator
Formula
This calculator uses the standard resistor color code calculator formula:
4-Band Formula
R = (10×D1 + D2) × 10^Multiplier ± Tolerance%
Frequently Asked Questions
How do I read a resistor color code?⌄
For a 4-band resistor: bands 1 and 2 give the first two digits, band 3 is the multiplier, and band 4 is tolerance. For example, Brown-Black-Red-Gold = 1,000 Ω ±5%.
What is a 4-band vs 5-band resistor?⌄
4-band resistors have two significant digits; 5-band resistors have three, providing higher precision. Most common resistors use 4 bands.
What does the gold or silver band mean?⌄
The gold or silver band (last band) indicates tolerance: gold = ±5%, silver = ±10%. If there is no band, tolerance is ±20%.
What color is a 1kΩ resistor?⌄
A 1 kΩ ±5% resistor has colour bands Brown-Black-Red-Gold (4-band) or Brown-Black-Black-Brown-Gold (5-band).
What color is a 10kΩ resistor?⌄
A 10 kΩ ±5% 4-band resistor is Brown-Black-Orange-Gold. The orange multiplier band represents ×1,000.
Why can't I read my resistor color?⌄
Resistors can fade or the colour ring spacing can be hard to read. Use a multimeter to measure actual resistance when in doubt.
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IEC 60062 — Marking codes for resistors and capacitors. 4-band, 5-band and 6-band colour codes, with tolerance and temperature-coefficient bands.
Core formula
value = (digits) × 10^multiplier, ± tolerance band
Why this matters
A 4-band and a 5-band resistor can look identical if you miscount — and the same colours then decode to a completely different value. Read from the tolerance band (gold/silver, and usually a wider gap) inward.
Independently verified
12 July 2026 — Re-derived from the governing standard and checked numerically against worked reference cases from the standard itself — not merely tested for “returns a number”.
Results are for guidance. Verify against the current edition of the governing standard and have a qualified professional review before use in practice.