Resistor Color Code: formula
Enter the digits or values for the four bands read from left to right, holding the resistor so the tolerance band, gold or silver, is on the right. The first two bands are digits, the third is the multiplier and the fourth is the tolerance. The colors map to digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9.
Brown, red and orange resistor bands can be visually confused.
Resistor Color Code: worked example
| First band | Brown (1) |
|---|---|
| Second band | Black (0) |
| Multiplier band | Red (×100) |
| Tolerance band | Gold (±5%) |
| Resistance (ohms) | 1,000 |
| Minimum (ohms) | 950 |
| Maximum (ohms) | 1,050 |
Five-band resistors use three digit bands, a multiplier and a tolerance, and give more precision. The reading direction matters, and reading from the wrong end gives a different value. Faded or burnt bands are unreliable, and some color pairs are hard for color-blind readers.
Surface-mount parts use printed codes.
Resistor Color Code: changing First band
| First band | Resistance (ohms) | Minimum (ohms) | Maximum (ohms) |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 1 (example) | 1,000 | 950 | 1,050 |
| 2 | 2,000 | 1,900 | 2,100 |
| 3 | 3,000 | 2,850 | 3,150 |
| 4 | 4,000 | 3,800 | 4,200 |
| 5 | 5,000 | 4,750 | 5,250 |
| 6 | 6,000 | 5,700 | 6,300 |
| 7 | 7,000 | 6,650 | 7,350 |
| 8 | 8,000 | 7,600 | 8,400 |
| 9 | 9,000 | 8,550 | 9,450 |
Resistor Color Code: compare input ranges
| Input | Tested from | To | Resistance (ohms): low input | Resistance (ohms): high input | Swing |
|---|---|---|---|---|---|
| First band | Black (0) | White (9) | 0 | 9,000 | 9,000 (500%) |
| Multiplier band | Black (×1) | Silver (×0.01) | 10 | 0.1 | 9.9 (99999%) |
| Second band | Black (0) | White (9) | 1,000 | 1,900 | 900 (50%) |
Resistor Color Code: individual input comparisons
| Input | Value | Resistance (ohms) | Minimum (ohms) | Maximum (ohms) |
|---|---|---|---|---|
| First band | Black (0) | 0 | 0 | 0 |
| Brown (1) | 1,000 | 950 | 1,050 | |
| Red (2) | 2,000 | 1,900 | 2,100 | |
| Orange (3) | 3,000 | 2,850 | 3,150 | |
| Yellow (4) | 4,000 | 3,800 | 4,200 | |
| Green (5) | 5,000 | 4,750 | 5,250 | |
| Blue (6) | 6,000 | 5,700 | 6,300 | |
| Violet (7) | 7,000 | 6,650 | 7,350 | |
| Gray (8) | 8,000 | 7,600 | 8,400 | |
| White (9) | 9,000 | 8,550 | 9,450 | |
| Second band | Black (0) | 1,000 | 950 | 1,050 |
| Brown (1) | 1,100 | 1,045 | 1,155 | |
| Red (2) | 1,200 | 1,140 | 1,260 | |
| Orange (3) | 1,300 | 1,235 | 1,365 | |
| Yellow (4) | 1,400 | 1,330 | 1,470 | |
| Green (5) | 1,500 | 1,425 | 1,575 | |
| Blue (6) | 1,600 | 1,520 | 1,680 | |
| Violet (7) | 1,700 | 1,615 | 1,785 | |
| Gray (8) | 1,800 | 1,710 | 1,890 | |
| White (9) | 1,900 | 1,805 | 1,995 | |
| Multiplier band | Black (×1) | 10 | 9.5 | 10.5 |
| Brown (×10) | 100 | 95 | 105 | |
| Red (×100) | 1,000 | 950 | 1,050 | |
| Orange (×1,000) | 10,000 | 9,500 | 10,500 | |
| Yellow (×10,000) | 100,000 | 95,000 | 105,000 | |
| Green (×100,000) | 1,000,000 | 950,000 | 1,050,000 | |
| Blue (×1,000,000) | 10,000,000 | 9,500,000 | 10,500,000 | |
| Violet (×10,000,000) | 100,000,000 | 95,000,000 | 105,000,000 | |
| Gray (×100,000,000) | 1,000,000,000 | 950,000,000 | 1,050,000,000 | |
| White (×1,000,000,000) | 10,000,000,000 | 9,500,000,000 | 10,500,000,000 | |
| Gold (×0.1) | 1 | 0.95 | 1.1 | |
| Silver (×0.01) | 0.1 | 0.095 | 0.105 | |
| Tolerance band | Brown (±1%) | 1,000 | 990 | 1,010 |
| Red (±2%) | 1,000 | 980 | 1,020 | |
| Green (±0.5%) | 1,000 | 995 | 1,005 | |
| Blue (±0.25%) | 1,000 | 997.5 | 1,002.5 | |
| Violet (±0.1%) | 1,000 | 999 | 1,001 | |
| Gray (±0.05%) | 1,000 | 999.5 | 1,000.5 | |
| Gold (±5%) | 1,000 | 950 | 1,050 | |
| Silver (±10%) | 1,000 | 900 | 1,100 |
Resistor Color Code: which assumptions move the result?
Resistor Color Code: values and definitions
| Quantity and definition | Value used |
|---|---|
| First band — The first significant digit. | Brown (1) |
| Second band — The second significant digit. | Black (0) |
| Multiplier band — The power of ten applied to the two digits. | Red (×100) |
| Tolerance band — How far the real value may differ. | Gold (±5%) |
| Resistance (ohms) | 1,000 |
| Minimum (ohms) | 950 |
| Maximum (ohms) | 1,050 |
Common error: Reading the bands from the wrong end. The tolerance band, usually gold or silver, goes on the right, and reading backward gives a different value.
Science & Electronics calculators: Voltage Divider Calculator, RC Time Constant Calculator, Combined Gas Law Calculator, Percent Yield Calculator, PPM Concentration Calculator, Ohm's Law Calculator.
Four colored bands encode a resistor's value: two digits, a multiplier and a tolerance. Brown, black and red read as 1, 0 and times 100, which is 1,000 ohms, and a gold band adds a 5 percent tolerance, so the real value may land between 950 and 1,050. Hold the resistor with the tolerance band at the right, since the bands start at the opposite end.
Measure with a multimeter when it matters. Bands can fade, and some colors look alike in poor light.
Combine resistors on the resistor calculator, compute LED currents on the LED resistor calculator, voltages on the voltage divider page and power on the Ohm's law calculator. The scientific notation page explains multipliers, and the RC time constant calculator uses resistor values.
Which end do I start reading from?
From the end farthest from the tolerance band, which is usually gold or silver and spaced apart from the others.
What does the tolerance band mean?
The percentage by which the actual resistance may differ from the marked value, so 5% on 1,000 ohms means 950 to 1,050.
How do I read a four-band resistor?
The first two bands are digits, the third is the power-of-ten multiplier and the fourth is the tolerance, with gold meaning 5% and silver 10%.