Resistor Value Calculator
Closest E12 value
680Ω
How it works
Resistors are marked with color bands that encode their resistance value and tolerance. The Resistor Value Calculator decodes 4-band, 5-band, and 6-band color codes into the resistance in ohms and the tolerance percentage.
**Color code system** Each color represents a digit 0 through 9 and a multiplier power of 10. For a 4-band resistor: band 1 = first significant digit, band 2 = second significant digit, band 3 = multiplier, band 4 = tolerance. Example: Brown-Black-Red-Gold = 1, 0, x100, plus/minus 5% = 1,000 ohms.
**5-band and 6-band resistors** Precision resistors use 5 bands: 3 significant digits plus multiplier plus tolerance. The 6th band on 6-band resistors encodes temperature coefficient (ppm per degree C) — important for precision analog circuits where resistance must stay stable across temperature changes.
**Tolerance and E-series** Resistors come in standard value series: E12 (10% tolerance, 12 values per decade), E24 (5%, 24 values), E48 (2%, 48 values), E96 (1%, 96 values). For precision work requiring 1% accuracy, use E96 series components.
**Reading the bands** Hold the resistor so the tolerance band (gold/silver/wide gap) is on the right. Left-to-right reading gives the significant digits. If unsure of orientation, read both ways and check which gives a standard value.
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Frequently Asked Questions
- The tolerance band (typically gold or silver) indicates how close the actual resistance is to the marked value. Gold = ±5% tolerance: a 1,000 ohm resistor could measure anywhere from 950 to 1,050 ohms and still be within spec. Silver = ±10%. Red = ±2%. Brown = ±1%. For most general electronics (LED current limiting, voltage dividers, pull-up/pull-down resistors), 5% tolerance is perfectly adequate. Precision analog circuits (audio, measurement equipment, instrumentation amplifiers) often need 1% or better to prevent offset errors and non-linearity.
- 4-band resistors: band 1 = first digit, band 2 = second digit, band 3 = multiplier (power of 10), band 4 = tolerance. Hold the resistor with the tolerance band on the right. 5-band resistors: band 1 = first digit, band 2 = second digit, band 3 = third digit, band 4 = multiplier, band 5 = tolerance. The extra band gives a third significant digit, enabling values like 1,000 ohms instead of just 1,000 ohms rounded to two digits. Orientation tip: the tolerance band is often wider or further separated from the other bands than on 4-band resistors. If uncertain, read from both directions and pick the value that matches an E-series standard value.
- The E-series defines the standard preferred values for resistors (and capacitors/inductors) within each decade. E12 has 12 values per decade (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82) and corresponds to 10% tolerance — any value within one decade is within 10% of the nearest E12 value. E24 has 24 values (5% tolerance). E96 has 96 values (1% tolerance), enabling values like 10.2k, 10.5k, 10.7k, 11.0k within the 10k–22k range. For most design work, E24 is sufficient. Use E96 when precise ratio or absolute value is critical.
- Yes. Set your multimeter to resistance (Ω) mode, select a range higher than the expected value, and touch the probes to the resistor leads (polarity doesn't matter for resistors). Read the displayed value and compare to the color code. Important: always measure resistors out of circuit — in-circuit measurement is unreliable because parallel components affect the reading. If a resistor measures significantly outside its tolerance band (e.g., 2,000 ohms when marked 1,000 ohms ±5%), it may be damaged by heat or overcurrent. Resistors typically fail open (infinite resistance) rather than short circuit.