150 Ohm Resistor: Color Code, Specifications & LED Circuit Applications

The 150 ohm resistor holds a special place in electronics workbenches around the world. If you’ve ever connected an LED to a 5V power supply and wondered what resistor to use, chances are a 150 ohm resistor was the answer. It’s one of those values that hits a sweet spot for common circuit configurations.

I’ve grabbed for this resistor value more times than I can count when prototyping LED circuits on breadboards. The brown-green-brown color pattern becomes instantly recognizable after you’ve built a few Arduino projects or microcontroller circuits.

What is a 150 Ohm Resistor?

A 150 ohm resistor provides exactly 150 ohms of electrical resistance to current flow. This value belongs to the standard E24 series, making it readily available from any electronics supplier in various package types and power ratings.

What makes this particular value so useful? It calculates out perfectly for driving standard LEDs from 5V logic supplies. When you run the numbers with a typical 2V forward voltage LED at 20mA, you get exactly 150 ohms. This mathematical coincidence makes the 150 ohm resistor the go-to choice for countless LED indicator circuits.

Key Specifications of 150 Ohm Resistors

Parameter	Typical Value	Notes
Resistance	150 Ω	E24 standard value
Common Tolerances	±5%, ±1%	Gold or Brown tolerance band
Power Ratings	1/8W, 1/4W, 1/2W, 1W	1/4W most common
Temperature Coefficient	50-250 ppm/K	Varies by construction type
Maximum Voltage	200-500V	Depends on power rating
Operating Temperature	-55°C to +155°C	Typical range

150 Ohm Resistor Color Code

Identifying a 150 ohm resistor by its color bands is straightforward. The distinctive brown-green-brown pattern stands out clearly once you know what to look for.

4-Band 150 Ohm Resistor Color Code

The standard 4-band configuration is what you’ll encounter most frequently:

Band Position	Color	Value	Meaning
1st Band	Brown	1	First significant digit
2nd Band	Green	5	Second significant digit
3rd Band	Brown	×10	Multiplier
4th Band	Gold	±5%	Tolerance

Reading it: Brown-Green-Brown-Gold gives you 15 × 10 = 150Ω with ±5% tolerance.

With a 5% tolerance, your actual resistance falls between 142.5Ω and 157.5Ω. For LED current limiting and most general applications, this tolerance works perfectly fine.

5-Band 150 Ohm Resistor Color Code

For precision applications requiring tighter tolerance:

Band Position	Color	Value	Meaning
1st Band	Brown	1	First significant digit
2nd Band	Green	5	Second significant digit
3rd Band	Black	0	Third significant digit
4th Band	Black	×1	Multiplier
5th Band	Brown	±1%	Tolerance

The 5-band code Brown-Green-Black-Black-Brown represents 150 × 1 = 150Ω with ±1% tolerance.

6-Band 150 Ohm Resistor Color Code

When temperature stability matters:

Band Position	Color	Value	Meaning
1st Band	Brown	1	First significant digit
2nd Band	Green	5	Second significant digit
3rd Band	Black	0	Third significant digit
4th Band	Black	×1	Multiplier
5th Band	Brown	±1%	Tolerance
6th Band	Brown	100 ppm/K	Temperature coefficient

Complete Color Code Reference Chart

Color	Digit	Multiplier	Tolerance
Black	0	×1	–
Brown	1	×10	±1%
Red	2	×100	±2%
Orange	3	×1,000	–
Yellow	4	×10,000	–
Green	5	×100,000	±0.5%
Blue	6	×1,000,000	±0.25%
Violet	7	–	±0.1%
Gray	8	–	±0.05%
White	9	–	–
Gold	–	×0.1	±5%
Silver	–	×0.01	±10%

SMD 150 Ohm Resistor Markings

Surface mount 150 ohm resistors use numerical codes instead of color bands. Understanding these markings prevents confusion during board assembly or rework.

3-Digit SMD Code

A 150 ohm resistor in 3-digit format is marked 151.

Breaking it down:

• First two digits (15) = significant figures
• Third digit (1) = number of zeros to add = one zero

Result: 15 + one zero = 150Ω

Important: Don’t confuse code 150 with 150 ohms. The code 150 actually means 15Ω (15 with zero zeros added). This trips up even experienced technicians.

4-Digit SMD Code

Precision SMD resistors use 1500 for 150 ohms:

• First three digits (150) = significant figures
• Fourth digit (0) = multiplier = ×1

Result: 150 × 1 = 150Ω

EIA-96 Code

For 1% tolerance SMDs, the EIA-96 system marks 150Ω as 02B:

• 02 = code for 150 in the E96 lookup table
• B = multiplier of ×10

SMD Marking System	Code for 150Ω	Typical Tolerance
3-Digit	151	±5%
4-Digit	1500	±1%
EIA-96	02B	±1%

SMD Package Sizes and Power Ratings

Package	Dimensions (mm)	Typical Power Rating
0201	0.6 × 0.3	1/20W (0.05W)
0402	1.0 × 0.5	1/16W (0.063W)
0603	1.6 × 0.8	1/10W (0.1W)
0805	2.0 × 1.25	1/8W (0.125W)
1206	3.2 × 1.6	1/4W (0.25W)
2010	5.0 × 2.5	1/2W (0.5W)
2512	6.3 × 3.2	1W

150 Ohm Resistor for LED Circuits

This is where the 150 ohm resistor truly shines. The math works out almost perfectly for 5V LED applications, making it the standard recommendation across countless tutorials and reference designs.

The LED Current Limiting Calculation

The formula is simple: R = (Vsupply – Vforward) / I

For a typical red or yellow LED:

• Supply voltage: 5V
• LED forward voltage: ~2V
• Desired current: 20mA

Calculation: (5V – 2V) / 0.020A = 150Ω

A 150 ohm resistor delivers exactly 20mA to your LED, which is the standard operating current for most indicator LEDs.

LED Current with 150 Ohm Resistor at Various Voltages

Supply Voltage	LED Type	Forward Voltage	Current	Brightness
3.3V	Red	2.0V	8.7mA	Dim
5V	Red	2.0V	20mA	Full
5V	Yellow	2.0V	20mA	Full
5V	Green	2.2V	18.7mA	Full
5V	Blue	3.2V	12mA	Moderate
5V	White	3.2V	12mA	Moderate
9V	Red	2.0V	46.7mA	Overdrive!
12V	Red	2.0V	66.7mA	Damage risk

Warning: At 9V or 12V, a 150 ohm resistor passes too much current for standard LEDs. Use 330Ω or 470Ω for higher voltage applications.

Power Dissipation in the Resistor

Always check that your resistor can handle the heat:

Scenario	Voltage Drop	Current	Power Dissipation
5V, Red LED	3V	20mA	60mW
5V, Blue LED	1.8V	12mA	21.6mW
9V, Red LED	7V	46.7mA	327mW
12V, Red LED	10V	66.7mA	667mW

A standard 1/4W (250mW) 150 ohm resistor handles 5V LED circuits easily. At 9V or 12V, you’d need a 1/2W or 1W resistor if you insist on using this value.

Applications for 150 Ohm Resistors

Beyond LED circuits, the 150 ohm resistor finds use in various applications across electronics design.

Common Circuit Applications

Application	Purpose	Typical Configuration
LED current limiting	Protect LEDs from overcurrent	Series with LED, 5V supply
Arduino indicator lights	Status LEDs on GPIO pins	GPIO → 150Ω → LED → GND
Pull-up/pull-down	Set logic levels	Between signal and rail
Voltage dividers	Scale down voltages	Paired with other resistors
RC timing circuits	Set time constants	With capacitors
Audio signal conditioning	Impedance matching	In signal paths
Transistor biasing	Set operating point	Base or emitter circuits
Current sensing	Measure small currents	In series with load

150 Ohm vs. Neighboring Values

Resistor Value	5V LED Current	Best For
100Ω	30mA	Maximum brightness (risky)
120Ω	25mA	Bright LEDs
150Ω	20mA	Standard operation
180Ω	16.7mA	Slightly dimmer, longer life
220Ω	13.6mA	Lower power, adequate brightness
330Ω	9.1mA	Dim but visible

The 150 ohm resistor hits the sweet spot for full brightness at the LED’s rated current.

Types of 150 Ohm Resistors

Different construction types suit different applications:

Resistor Types and Characteristics

Type	Tolerance	Temperature Coefficient	Best Applications
Carbon Film	±5%	±200-500 ppm/K	General purpose, hobbyist
Metal Film	±1%	±50-100 ppm/K	Precision circuits
Thick Film SMD	±1-5%	±100-200 ppm/K	Production boards
Thin Film SMD	±0.1-1%	±25-50 ppm/K	High precision
Wirewound	±1-5%	±20-100 ppm/K	High power

For LED current limiting, a standard carbon film 150 ohm resistor works perfectly. Precision circuits may warrant metal film types for better stability.

How to Measure a 150 Ohm Resistor

Verification is always a good idea, especially with old or unknown components.

Multimeter Measurement Steps

1. Set your multimeter to resistance mode (Ω)
2. Select the 200Ω or 2kΩ range
3. Touch probes to each lead of the resistor
4. Read the displayed value

A 150 ohm resistor with 5% tolerance should read between 142.5Ω and 157.5Ω. Readings outside this range indicate a damaged or mis-marked component.

In-Circuit Measurement Considerations

Measuring resistors while installed in a circuit can give misleading results:

Scenario	Effect on Reading
Parallel resistors nearby	Lower reading than actual
Capacitors in circuit	Unstable reading
Semiconductor junctions	Lower reading
Circuit powered on	Potentially dangerous and inaccurate

Always power down circuits and discharge capacitors before measuring resistance.

Useful Resources and Tools

Online Calculators

• DigiKey Resistor Color Code Calculator – Decode any color band pattern
• DigiKey SMD Resistor Code Calculator – Convert SMD markings
• LED Calculator – Design LED arrays with correct resistors
• Calculator.net Resistor Calculator – Series and parallel calculations

Component Suppliers

• DigiKey – Wide selection with parametric search
• Mouser – Comprehensive inventory
• Newark – Industrial and hobbyist supply
• SparkFun – Hobbyist-friendly kits and components
• Adafruit – Maker-focused electronics

Learning Resources

• Resistor Guide – Comprehensive resistor theory
• SparkFun Resistor Tutorial – Beginner-friendly guide
• All About Circuits – In-depth electronics education

Frequently Asked Questions

What is the color code for a 150 ohm resistor?

The 4-band 150 ohm resistor color code is Brown-Green-Brown-Gold. Brown represents 1, Green represents 5, the second Brown is a ×10 multiplier, and Gold indicates ±5% tolerance. Multiply 15 by 10 to get 150 ohms. For 5-band precision resistors, the code is Brown-Green-Black-Black-Brown with ±1% tolerance.

Can I use a 150 ohm resistor for any LED?

A 150 ohm resistor works ideally for red, yellow, orange, and older green LEDs with a 5V power supply. These LEDs typically have forward voltages around 2V, resulting in 20mA current flow. For blue, white, and newer green LEDs with higher forward voltages (3-3.4V), a 150 ohm resistor is safe but delivers less current (about 12mA), resulting in reduced brightness. Consider 68-100 ohms for brighter blue and white LEDs at 5V.

What is the SMD code for a 150 ohm resistor?

In the 3-digit SMD marking system, a 150 ohm resistor is marked 151 (15 with one zero added). Don’t confuse this with code 150, which actually means 15 ohms. For 4-digit precision resistors, the marking is 1500. The EIA-96 code used on some 1% resistors is 02B.

Can I substitute a 220 ohm resistor for a 150 ohm?

Yes, you can substitute a 220Ω for a 150 ohm resistor in LED circuits. The LED will be dimmer (about 13.6mA instead of 20mA at 5V) but will still illuminate clearly and actually have a longer lifespan due to reduced current stress. Going in the opposite direction, substituting 100Ω for 150Ω increases current to 30mA, which may exceed the LED’s rating and shorten its life or cause immediate damage.

What wattage 150 ohm resistor do I need for LED circuits?

For standard 5V LED circuits, a 1/4W (0.25W) 150 ohm resistor is more than adequate. The power dissipation is only about 60mW. If you’re driving LEDs from higher voltages like 9V or 12V (which isn’t recommended with 150Ω), you would need 1/2W or 1W resistors to handle the increased heat. Always calculate power dissipation as P = I² × R and choose a resistor rated for at least twice the calculated value for reliable operation.

Summary

The 150 ohm resistor earns its place as a staple component through pure practicality. The math aligns perfectly for 5V LED circuits at 20mA, making it the automatic choice for indicator lights in countless Arduino projects, embedded systems, and prototype circuits.

With its distinctive Brown-Green-Brown-Gold color code for 4-band versions and SMD marking of 151, identifying this resistor becomes second nature after a few projects. Keep a supply of these resistors in your parts collection. Whether you’re building a simple LED blinker or designing production hardware, the 150 ohm resistor will likely find its way into your circuit.

For 3.3V systems, you’ll want lower values. For 9V and 12V applications, step up to 330Ω or 470Ω. But for the ubiquitous 5V supply voltage that dominates hobbyist and professional electronics alike, 150Ω remains the gold standard for LED current limiting.