680 Ω resistor color code
A 680 Ω resistor is Blue, Gray, Brown, Gold: 68 × 10 = 680 Ω, ±5%, so anything from 646 to 714 Ω is in spec.
68 × 10 = 680 Ω
5-band version
Blue · Gray · Black · Black · Brown = 680 Ω ±1%
680 × 1 = 680 Ω. Range 673.2–686.8 Ω (±1%).
Open the 5-band version
Where you'll meet it
A bright LED on a 12 V battery
A 12 V lead-acid battery, the kind in alarm panels, ride-on toys and solar setups, can light an LED through one resistor. Here 680 Ω sits between the battery's plus and a red LED and sets the current.
I = (12 V − 2.0 V) / 680 Ω ≈ 14.7 mA
That is bright, and under the 20 mA that most standard LEDs are rated for.
While the battery is on charge it can sit at about 14.4 V: then (14.4 V − 2.0 V) / 680 Ω ≈ 18.2 mA, still under 20 mA.
A blue or white LED drops about 3.0 V, so the same resistor gives (12 V − 3.0 V) / 680 Ω ≈ 13.2 mA.
The resistor turns (14.7 mA)² × 680 Ω ≈ 0.147 W into heat, and (18.2 mA)² × 680 Ω ≈ 0.23 W while the battery charges. Use a ½ W (0.5 W) part: a ¼ W one would run hot.
2.0 V and 20 mA are typical figures for a standard 5 mm red LED. Check your LED's datasheet. A lead-acid battery reads a little over 12 V when full and sags as it empties, so the current drifts with it. The LED lights only one way round: its longer leg goes toward the battery's plus. If it stays dark, turn it round: 12 V backwards is more than the 5 V most LEDs are rated to block. A lead-acid battery can deliver a huge current, so never let the wires touch, and never connect the LED without the resistor.
On SMD parts
Look for 681 or 6800
- 681681 = 68 × 10¹ = 680 Ω (3-digit code).
- 68006800 = 680 × 10⁰ = 680 Ω (4-digit code, usually ±1% parts).
There is no EIA-96 code, because 680 Ω is not an E96 value (the nearest E96 values are 665 Ω and 681 Ω). A part marked 680 is 68 Ω, not 680 Ω.
Don't mix it up
Only band 3 changes
These four share Blue, Gray and Gold. Brown (×10) is 680 Ω; black is ten times less and red ten times more.
68 Ωband 3 black- 680 Ωband 3 brownThis page
6.8 kΩband 3 red
68 kΩband 3 orange
Check it with a meter
Read 646–714 Ω
- Take the resistor out of the circuit.
- Set the meter to Ω, range 2 kΩ (or auto).
- Touch one probe to each lead. Keep your fingers off the metal: your body is a resistor too.
- Anything from 646 to 714 Ω is a good ±5% part. A 5-band ±1% part should read 673.2 to 686.8 Ω.
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.
Spot it
Can you find 680 Ω in a pile?
Practise reading it, and its look-alikes, in the resistor challenge.
Try the resistor challenge680 Ω resistor FAQ
Why use 680 Ω and not 470 Ω for an LED on 12 V?
With a typical red LED (about 2.0 V), 470 Ω on 12 V gives (12 V − 2.0 V) / 470 Ω ≈ 21.3 mA, already over the 20 mA most standard LEDs are rated for, and about 26.4 mA while the battery charges at 14.4 V. 680 Ω gives (12 V − 2.0 V) / 680 Ω ≈ 14.7 mA, and about 18.2 mA on charge. Use a ½ W (0.5 W) part for it.
What is the SMD code for a 680 Ω resistor?
681 on 3-digit parts (68 × 10¹) and 6800 on 4-digit parts (680 × 10⁰). There is no EIA-96 code, because 680 Ω is not an E96 value.
What are the 5-band colors for 680 Ω?
Blue, Gray, Black, Black, Brown: 680 × 1 = 680 Ω with ±1% tolerance, so 673.2 to 686.8 Ω.
What does 680R mean?
680R is another way to write 680 Ω. The R stands for ohms and sits where the decimal point would be, so 4R7 means 4.7 Ω. With nothing after the R, 680R is exactly 680 Ω.
Bands, ranges and codes come from the same engine as the calculator. Last reviewed .