Do you need to know the color coding of resistors to calculate its value? Here we show you what it is, how to calculate the value of a resistor and an online calculator through which you can select the color of each band and calculate its value without making calculations.
We leave you with the resistance calculator The four-band display, in which you simply select the color of each band and it will automatically show you its value and tolerance.
The color code of the resistors
For calculate the value of a resistor The first thing we have to do is to identify the number of bands it has. There can be 4, 5 or 6 bands, so depending on the type of resistance, each band will mean one thing, so here is a summary for you to understand the function of each one:
|4-band resistor||5-band resistor||6-band resistor|
|1st band||1st significant digit||1st significant digit||1st significant digit|
|2nd band||2nd significant digit||2nd significant digit||2nd significant digit|
|3rd band||multiplier||3rd significant digit||3rd significant digit|
|6th band||-||-||temperature coefficient|
Now that you know what each band is used for, let's take a look at the color coding of the resistors.
|Color||1st Band||2nd Band||3rd Band||Multiplier||Tolerance||Coef. temp.|
If you want to know a little more about what each of the bands means, let's take a look at each of them in a little more detail below:
Each color represents a number if it is in the first and second band in the case of 4-band resistors. If the resistor is a 5- or 6-band resistor, the first three bands are significant digits.
The multiplier can be found in:
- The third band if it is a 4-band resistor.
- On the fourth band if we have a 5 or 6 band resistor
If you look, the number of zeros of each color is equal to the number we have seen in the columns of significant digits. That is, if the white color corresponds to 9 as a significant number, it will multiply by x1000000000 (there are 9 zeros) in its work as a multiplier. This happens in the same way with the rest of the colors.
Tolerance in a resistance gives us a margin of error that can be above or below the total value. of resistance.
The tolerance value is in the fourth or fifth band and its value is also determined according to the color code of the resistor.
For example, if we have a 5KΩ resistor with a tolerance of ±5%, that means that its actual value can range from 4,750 Ω to 5,250 Ω.
Logically, the smaller the tolerance, the more likely it is that the resistance value will be what it should theoretically be.
How to calculate the value of a resistor
For calculating the ohms value of a resistor we simply need to do the following steps:
- Identify significant numbers and group them in order.
- Multiply the significant numbers by the value of the multiplier
- Add to the result other parameters such as tolerance or temperature coefficient.
The procedure is similar for any resistanceeither 4, 5 or 6 bands.
For example, if we have a four band resistor with the colors green, blue, red and gold, let's calculate its value in ohms:
|1st Band||2nd Band||3rd Band||4th Band|
56 x 100 = 5600Ω with ±5% = 5.6 KΩ ±5%
Here is a collection of solved exercises for you to practice with different values.
4-band resistance exercises
Calculate the value of the following four-band resistors based on the colors below:
- Green, blue, red, gold: 5.6 KΩ and ±5%
- Red, yellow, orange, gold: 24 KΩ and ±5%
- Blue, gray, yellow, silver: 680 KΩ and ±10%
5-band resistance exercises
Obtain how much the following five-band resistors are worth in ohms:
- Red, yellow, orange, black, brown: 243 ohms and ± 1%
Examples of 6-band resistors
Find the value of the following six-band resistors, including their tolerance and temperature coefficient:
- Red, red, brown, brown, brown, brown. red: 2.21 KΩ, ±1% and 50ppm/ºC.
- White, black, white, white, brown, red, red: 9.09 KΩ, ±2% and 50ppm/°C
Frequently Asked Questions
Here we will answer some of the most common questions that arise when it comes to the following questions calculate the value or work with the color coding of resistors:
Resistance has only 3 bands
If you come across a resistor that has 3 bands, you can calculate its value as if it were a 4-band resistor (digit, digit and multiplier).
For tolerance we will put a 20%.
Which band is first in a resistance?
There are a number of rules for knowing which is the first band in a resistance:
- Some resistors have groupings of several bands close together and then one or two more separate ones. Put the band grouping to your left and calculate the resistance value from left to right.
- Resistors that have a tolerance of a 5% (gold) or a 10% (silver), it is very easy since in these cases we already know that that band will be the last. Therefore, put the gold or silver band on the right and calculate the resistance value from left to right.
- As mentioned in the previous point, the first band can never be silver or gold. Nor is it usual to find a black first band. For
What happens if I calculate the resistance value backwards?
If you have not been able to see which is the first band of the resistor and you have calculated the value of the resistor, ehe result you will probably have obtained does not appear in the table of usual resistor values.
Yes the resistance you have calculated does not have a standard valueIf you have done it wrong, it is likely that you have done it wrong.
You can also use a multimeter to obtain the value of a resistor to check if the calculation you have made is correct or not.
Our resistance calculator allows you to calculate the value in ohms of four band resistors, i.e., the most common in school or even university work.
You must simply choose the color of each band from left to right and you will automatically get the value in ohms of the resistance, including the tolerance.
Doubts about how to calculate the value of a resistor from the color coding? Leave us a comment and we will help you!