What Is a Standard Resistor Value?

First defined in 1952 by the IEC (International Electrotechnical Commission), resistor values aim to standardize the resistance and tolerance of resistors across the world. This makes it easier for consumers and electrical engineers to pick the right components for their circuits. It also provides manufacturers with a template to follow.

Using resistors of the wrong values can lead to unexpected results within a circuit. For example, if you use a resistor with poor tolerances with a sensitive LED, you run the risk of too much power making it to the LED. This can cause circuits to fail and even damage components. A standard surface-mount resistor’s ohmage and tolerance can be found by reading resistor color codes.

Common Standard Resistor Values

Preferred values, also known as E-series, are split into groups based on their tolerance. The tolerance of a resistor describes the potential difference between its rated resistance and its actual resistance.

For example, an E3 series resistor has a tolerance of 40%. This means that an E3 resistor with a resistance rating of 100 ohms will actually have a resistance between 60 and 140 ohms. Each series is split further into a set of resistance values.

E Series & Resistance Values

Each E series has its own set of resistance values that sit between one and ten, with the number of steps (on a logarithmic scale) being equal to the E number. These values represent the different ohmage options available within the series, and they can be multiplied by 10, 100, 1000, etc. for the full resistance range.

For example, E3 resistors have the following three values; 1.0, 2.2, and 4.7. This means that E3 resistors can have a resistance of 1Ω, 2.2Ω, or 4.7Ω, but they can also have resistances of 10Ω, 22Ω, and 47Ω, or 100Ω, 220Ω, and 470Ω. This continues into millions of ohms.

E6 Series Tolerances & Resistance Values

E6 series resistors have a tolerance of 20% and the following six values.

1. 0, 1. 5, 2. 2, 3. 3, 4. 7, and 6. 8

E12 Series Tolerances & Resistance Values

E12 series resistors have a tolerance of 10% and the following 12 values.

1. 0, 1. 2, 1. 5, 1. 8, 2. 2, 2. 7, 3. 3, 3. 9, 4. 7, 5. 6, 6. 8, and 8. 2

E24 Series Tolerances & Resistance Values

E24 series resistors have a tolerance of 5% and the following 24 values.

1. 0, 1. 1, 1. 2, 1. 3, 1. 5, 1. 6, 1. 8, 2. 0, 2. 2, 2. 4, 2. 7, 3. 0, 3. 3, 3. 6, 3. 9, 4. 3, 4. 7, 5. 1, 5. 6, 6. 2, 6. 8, 7. 5, 8. 2, and 9. 1

E48 Series Tolerances & Resistance Values

E48 series resistors have a tolerance of 2% and the following 48 values.

1. 00, 1. 05, 1. 10, 1. 15, 1. 21, 1. 27, 1. 33, 1. 40, 1. 47, 1. 54, 1. 62, 1. 69, 1. 78, 1. 87, 1. 96, 2. 05, 2. 15, 2. 26, 2. 37, 2. 49, 2. 61, 2. 74, 2. 87, 3. 01, 3. 16, 3. 32, 3. 48, 3. 65, 3. 83, 4. 02, 4. 22, 4. 42, 4. 64, 4. 87, 5. 11, 5. 36, 5. 62, 5. 90, 6. 19, 6. 49, 6. 81, 7. 15, 7. 50, 7. 87, 8. 25, 8. 66, 9. 09, and 9. 53

E96 Series Tolerances & Resistance Values

E96 series resistors have a tolerance of 1% and the following 96 values.

1. 00, 1. 02, 1. 05, 1. 07, 1. 10, 1. 13, 1. 15, 1. 18, 1. 21, 1. 24, 1. 27, 1. 30, 1. 33, 1. 37, 1. 40, 1. 43, 1. 47, 1. 50, 1. 54, 1. 58, 1. 62, 1. 65, 1. 69, 1. 74, 1. 78, 1. 82, 1. 87, 1. 91, 1. 96, 2. 00, 2. 05, 2. 10, 2. 15, 2. 21, 2. 26, 2. 32, 2. 37, 2. 43, 2. 49, 2. 55, 2. 61, 2. 67, 2. 74, 2. 80, 2. 87, 2. 94, 3. 01, 3. 09, 3. 16, 3. 24, 3. 32, 3. 40, 3. 48, 3. 57, 3. 65, 3. 74, 3. 83, 3. 92, 4. 02, 4. 12, 4. 22, 4. 32, 4. 42, 4. 53, 4. 64, 4. 75, 4. 87, 4. 99, 5. 11, 5. 23, 5. 36, 5. 49, 5. 62, 5. 76, 5. 90, 6. 04, 6. 19, 6. 34, 6. 49, 6. 65, 6. 81, 6. 98, 7. 15, 7. 32, 7. 50, 7. 68, 7. 87, 8. 06, 8. 25, 8. 45, 8. 66, 8. 87, 9. 09, 9. 31, 9. 53, and 9. 76

E192 Series Tolerances & Resistance Values

E192 series resistors have a tolerance of 0.5% or lower and the following 192 values.

1. 00, 1. 01, 1. 02, 1. 04, 1. 05, 1. 06, 1. 07, 1. 09, 1. 10, 1. 11, 1. 13, 1. 14, 1. 15, 1. 17, 1. 18, 1. 20, 1. 21, 1. 23, 1. 24, 1. 26, 1. 27, 1. 29, 1. 30, 1. 32, 1. 33, 1. 35, 1. 37, 1. 38, 1. 40, 1. 42, 1. 43, 1. 45, 1. 47, 1. 49, 1. 50, 1. 52, 1. 54, 1. 56, 1. 58, 1. 60, 1. 62, 1. 64, 1. 65, 1. 67, 1. 69, 1. 72, 1. 74, 1. 76, 1. 78, 1. 80, 1. 82, 1. 84, 1. 87, 1. 89, 1. 91, 1. 93, 1. 96, 1. 98, 2. 00, 2. 03, 2. 05, 2. 08, 2. 10, 2. 13, 2. 15, 2. 18, 2. 21, 2. 23, 2. 26, 2. 29, 2. 32, 2. 34, 2. 37, 2. 40, 2. 43, 2. 46, 2. 49, 2. 52, 2. 55, 2. 58, 2. 61, 2. 64, 2. 67, 2. 71, 2. 74, 2. 77, 2. 80, 2. 84, 2. 87, 2. 91, 2. 94, 2. 98, 3. 01, 3. 05, 3. 09, 3. 12, 3. 16, 3. 20, 3. 24, 3. 28, 3. 32, 3. 36, 3. 40, 3. 44, 3. 48, 3. 52, 3. 57, 3. 61, 3. 65, 3. 70, 3. 74, 3. 79, 3. 83, 3. 88, 3. 92, 3. 97, 4. 02, 4. 07, 4. 12, 4. 17, 4. 22, 4. 27, 4. 32, 4. 37, 4. 42, 4. 48, 4. 53, 4. 59, 4. 64, 4. 70, 4. 75, 4. 81, 4. 87, 4. 93, 4. 99, 5. 05, 5. 11, 5. 17, 5. 23, 5. 30, 5. 36, 5. 42, 5. 49, 5. 56, 5. 62, 5. 69, 5. 76, 5. 83, 5. 90, 5. 97, 6. 04, 6. 12, 6. 19, 6. 26, 6. 34, 6. 42, 6. 49, 6. 57, 6. 65, 6. 73, 6. 81, 6. 90, 6. 98, 7. 06, 7. 15, 7. 23, 7. 32, 7. 41, 7. 50, 7. 59, 7. 68, 7. 77, 7. 87, 7. 96, 8. 06, 8. 16, 8. 25, 8. 35, 8. 45, 8. 56, 8. 66, 8. 76, 8. 87, 8. 98, 9. 09, 9. 20, 9. 31, 9. 42, 9. 53, 9. 65, 9. 76, and 9. 88

Choosing the Correct Resistor Value

The value you choose for your resistor should be based on a couple of factors. Price is important, with higher E series resistors generally having a higher cost due to their lower tolerance (i.e. higher accuracy of ohmage value). Alongside this, you also need to consider the requirements of your circuit.