Check a 100k resistor in the calculator
The calculator is set to 100 kΩ with a gold tolerance band. Switch to 5 or 6 bands, change the tolerance, or choose “Read the bands” to decode a resistor you are holding.
100k resistor colour bands
A 100 kΩ resistor carries the same value in every marking system; only the number of bands changes. Read from the end with the bands bunched closest to it, with the tolerance band, usually gold or brown and set slightly apart, on the right.
| Marking | Colours | Drawing | Where you see it |
|---|---|---|---|
| 4 bands, ±5 % | brown, black, yellow, gold | The most common through-hole marking | |
| 5 bands, ±1 % | brown, black, black, orange, brown | Precision metal-film resistors | |
| 6 bands, ±1 %, 100 ppm/K | brown, black, black, orange, brown, brown | Adds a temperature-coefficient band | |
| 3 bands, ±20 % | brown, black, yellow | Old parts with no tolerance band |
How to read brown, black, yellow, gold
- First band, brown: first digit 1.
- Second band, black: second digit 0, giving 10.
- Third band, yellow: multiply by 10,000, giving 100,000 Ω = 100 kΩ.
- Fourth band, gold: tolerance ±5 %.
On the 5-band version the first three bands are digits (100) and the fourth is the multiplier (×1,000), which comes to the same 100 kΩ. Check any other combination with the resistor color code calculator.
What a 100k resistor should measure
Tolerance is how far the real resistance may sit from the marked value. Measured out of circuit with a meter, a good 100 kΩ resistor reads within these limits:
| Tolerance | Band | Lowest | Highest |
|---|---|---|---|
| ±1 % | Brown | 99 kΩ | 101 kΩ |
| ±2 % | Red | 98 kΩ | 102 kΩ |
| ±5 % | Gold | 95 kΩ | 105 kΩ |
| ±10 % | Silver | 90 kΩ | 110 kΩ |
| ±20 % | None (no band) | 80 kΩ | 120 kΩ |
Measure it out of circuit, or with one leg lifted, and keep your fingers off both leads: at 100 kΩ your body’s resistance in parallel pulls the reading down noticeably.
Is 100k a standard resistor value?
Yes. 100 kΩ belongs to the E3, E6, E12, E24, E48, E96, E192 series of IEC 60063, so it is made in every tolerance from ±20 % down to ±0.1 %. The neighbouring E12 values are 82 kΩ below and 120 kΩ above. All the series are listed on our E-series resistor values page.
SMD code for 100 kΩ
- 3-digit code (usually ±5 %):
104. - 4-digit code (usually ±1 %):
1003. - EIA-96 code (±1 % chips in 0603 and smaller):
01D: code 1 for the digits, the letter for the multiplier.
Decode any chip marking with the SMD resistor code calculator.
Current, power and wattage
By Ohm’s law, I = V ÷ R and P = V² ÷ R. With the whole supply across a 100 kΩ resistor:
| Across | Current | Power | Rating to use |
|---|---|---|---|
| 3.3 V | 33 µA | 109 µW | ⅛ W |
| 5 V | 50 µA | 250 µW | ⅛ W |
| 12 V | 120 µA | 1.44 mW | ⅛ W |
| 24 V | 240 µA | 5.76 mW | ⅛ W |
A ¼ W 100 kΩ resistor reaches its full rating at 158 V (V = √(P × R)). In series with a red LED (about 2 V) on a 5 V supply it passes 30 µA, too little to light most LEDs visibly. The LED resistor calculator finds the right value for any LED and supply.
What a 100k resistor is used for
100 kΩ suits circuits that must draw almost no current: battery-voltage dividers that feed an ADC, op-amp feedback networks, and timing circuits with small capacitors. Its low current is also its weakness: on long wires and in damp conditions it picks up noise and leakage that a lower value would swamp.
Mistakes when reading a 100k resistor
The multiplier band moves the value by a factor of ten for every colour step, so it is the band to check twice, in good light. These are the misreadings that catch people out with 100 kΩ:
- Yellow read as orange. Brown, black, orange, gold would be 10 kΩ, 10 times too low.
- Reading the 4-band code backwards. It can’t be done: gold is not a digit colour, which is how you know which end comes first.
- Reading the 5-band code backwards. Brown, orange, black, black, brown reads as 130 Ω ±1 %, a plausible value, so this mistake goes unnoticed. The tolerance band is usually a little apart from the others; if you can’t tell, measure it.
Making 100 kΩ from other values
No 100 kΩ in the drawer? Two common E12 values can stand in, within 1 %: in series, 18 kΩ + 82 kΩ = 100 kΩ; 33 kΩ + 68 kΩ = 101 kΩ; in parallel, 180 kΩ ∥ 220 kΩ = 99 kΩ. Two 100 kΩ resistors give 200 kΩ in series and 50 kΩ in parallel.
Colour codes for other common values
- 1 ohm resistor: brown, black, gold
- 100 ohm resistor: brown, black, brown
- 220 ohm resistor: red, red, brown
- 330 ohm resistor: orange, orange, brown
- 470 ohm resistor: yellow, violet, brown
- 1k resistor: brown, black, red
- 4.7k resistor: yellow, violet, red
- 10k resistor: brown, black, orange
- 1M resistor: brown, black, green
Colours follow IEC 60062:2016. Codes, ranges and currents on this page are computed by the same engine as the resistor colour code calculator; see our methodology.