10 kΩ resistor color code

Where you'll meet it

A push-button pull-down on a 5 V input

The button connects 5 V to input pin D2. The 10 kΩ resistor connects the same pin to ground, so the pin reads LOW when the button is up instead of floating and picking up noise.

I = 5 V / 10 kΩ = 0.5 mA

Button up: no current flows, the resistor holds the pin at 0 V and it reads LOW.

Button down: the pin is at 5 V and reads HIGH. Only 0.5 mA flows through the resistor, and it turns 5 V × 0.5 mA = 0.0025 W into heat, so any ¼ W part is fine.

On a 3.3 V board, wire the button to 3.3 V, not 5 V: then 3.3 V / 10 kΩ = 0.33 mA.

The input itself draws almost nothing, so it does not change these numbers. A real button also bounces for a few milliseconds when pressed; handle that in code.

On SMD parts

Look for 103, 1002 or 01C

• 103103 = 10 × 10³ = 10,000 Ω (3-digit code).
• 10021002 = 100 × 10² = 10,000 Ω (4-digit code, usually ±1% parts).
• 01C01C = 100 × 100 = 10,000 Ω (EIA-96: 01 means 100, C means ×100).

10 kΩ has an EIA-96 code because 100 is the first value in the E96 series.

Check it with a meter

Read 9.5–10.5 kΩ

1. Take the resistor out of the circuit.
2. Set the meter to Ω, range 20 kΩ (or auto).
3. Touch one probe to each lead. Keep your fingers off the metal: your body is a resistor too. At 10 kΩ this matters: two fingers on the leads can pull the reading down.
4. Anything from 9.5 to 10.5 kΩ is a good ±5% part. A 5-band ±1% part should read 9.9 to 10.1 kΩ.

A meter has a small error of its own, so a reading a hair outside the range does not prove the part is bad. Measure again with firm contact before you swap it.