330 Ohm Resistor Color Code — Arduino Kit & 3.3 V vs 5 V Matrix

330 Ω & the Arduino starter-kit tradition

Orange · Orange · Brown · Gold → $33 × 10$ = 330 Ω. Both digit bands orange (3) — easy to spot in a mixed pile.

4-band: Orange · Orange · Brown · Gold → 33 × 10 = 330 Ω (±5%) · 5-band (±1%): Orange · Orange · Black · Black · Brown → 330 × 1 = 330 Ω (±1%)

This page is the supply-voltage vs LED brightness reference. Band-reading basics: beginner's guide.

Supply voltage matrix (same 330 Ω, same red LED)

MCU / rail	$V_f ≈ 2 V$	Current ≈ $(V−2)/330$	Visible?
5 V (UNO)	2 V	~9 mA	Yes — kit default
3.3 V (ESP32, Pico 3V3)	2 V	~4 mA	Often dim
3.3 V + blue LED ($V_f≈3 V$)	3 V	~1 mA	Usually insufficient

Takeaway: 330 Ω is optimized for 5 V + red/yellow LED. On 3.3 V projects, jump to 220 Ω or calculate with the LED calculator.

Identify 330 Ω in a mixed resistor strip

1. Look for two orange bands next to each other (digits side)
2. Third band brown (×10), not black (×1 → 33 Ω)
3. Fourth gold on the right (±5%)

If you see	Value
Orange · Orange · Brown · Gold	330 Ω
Orange · Orange · Black · Gold	33 Ω
Orange · White · Brown · Gold	390 Ω

Breadboard wiring checklist (5 V indicator)

1. GPIO → 330 Ω → LED anode (long leg)
2. LED cathode → GND
3. Confirm polarity — reverse LED won't light regardless of correct color code
4. Meter the resistor out-of-circuit if bands are worn

FAQ

330 vs 220 ohm for LEDs?

330 Ω = lower current, cooler, dimmer. 220 Ω = brighter on 5 V. Compare table on 220 Ω page.

330 ohm color code?

Orange, Orange, Brown, Gold.

Related guides (different topics)

• 220 Ω color code — LED brightness vs 330/470 Ω on 5 V

• 470 Ω color code — textbook LED history & Y-V family

• 1 kΩ color code — divider math & strong pull-ups

• Values hub — pick by application

• How to read any resistor (method)

• Decode bands online