How to read capacitor values (Beginners guide, 2024)
Understanding the capacitor value is crucial for proper circuit design and troubleshooting. There are ways of reading the capacitance value.
Larger capacitors display their capacitance, operating voltage, and tolerance directly. Small capacitors, due to size constraints, use shorthand codes or color codes. If the capacitor has two digits printed on it, the number is capacitance in picofarad and if it has three digits, the third digit represents a number of zeros added to the first two digits. The result is the capacitance in the picofarad.
In this article, we will provide a detailed guide on how to read capacitor values, covering the most common methods used for different capacitors.
Capacitor value reading
Electric charges are stored in an electrical component called a capacitor.
It is composed of two conductive plates and a dielectric, which acts as an insulator between them. Metal plates that conduct electricity are attached to the power source.
When a voltage is applied across the two plates of a capacitor, an electric field is created within the dielectric material, causing positive charges to accumulate on one plate and negative charges on the other plate.
The accumulation of charges creates an electric potential difference, or voltage, between the plates.
The amount of charge that a capacitor can store is determined by its capacitance, which is measured in farads (F). Farads is a larger unit so capacitors have capacitance in mircofarads or picofarads.
Check out our detailed article: Capacitor Basics for beginners
There are various types of representation used to identify the capacitance value.
Let’s discuss how to read capacitor value.
1. Numeric methods
For capacitors that have a larger surface area, the numeric method is used. In this method, the capacitance value is directly printed on the capacitor.
The unit of measurement used in this method is picofarads (pF) or microfarads (µF). The numeric value represents the capacitance. Follow the steps to identify the capacitance value.
- Inspect the surface of the capacitor and look for any numbers printed on it. The numbers are usually expressed as a three-digit value.
- The numeric value directly represents the capacitance. For example, if you see the number “100” printed on the capacitor, it indicates a capacitance of 100, and the unit will be mentioned with indicated number.
- Sometimes, capacitors with higher values may include prefixes to denote larger units of capacitance. Common prefixes include micro (µ), milli (m), and farads (F).
For example, if the capacitor has a 220 value printed on it then the capacitance value is 220pF.
2. Digit code
Capacitor values are commonly represented using the three-digit coding technique. In this method the unit picofarads is used.
Three digits are used in this manner to encode the capacitance value: the multiplier is represented by the third digit, and the first two digits denote the significant figures.
- Identify the code or three-digit number on the capacitor surface of the capacitor. Let the capacitor have a number ‘473’.
- Determine the significant figures. The first two digits of the code represent the significant figures of the capacitance value. In our example, “47” is the significant figure.
- Determine the multiplier. The multiplier that needs to be applied to the significant figures is indicated by the code’s third digit. In our example, the third digit is ‘3’ which corresponds to a multiplier of 10,00 (10^3).
- Calculate the capacitance value. By multiplying the significant number by the multiplier. So we have to multiply “47” by 10^4.
Capacitance = significant figure * multiplier
Capacitance = 47 * 10,00
Capacitance = 47,000 picofarads (pF)
So the three-digit code ‘473’ has a capacitance of 47,000 picofarads.
3. Color codes
Tantalum capacitors are frequently color-coded, with colored bands printed on the capacitor body. Each color represents a numerical digit, while the final color symbolizes the multiplier.
You can precisely determine the capacitance value by using a color-code chart that the manufacturer provides.
There are five color bands or dots, the first three colors represent the value of capacitance, the fourth band is for tolerance, and the fifth band shows the temperature coefficient.
Here is a step-by-step guideline to identify the capacitance of a capacitor.
- Examine the capacitor and identify the colored bands or stripes. Usually, there are four or five color bands on the capacitor body.
- Determine the value of each color band based on the color code chart. Here is a standard color code chart for capacitors:
| Color | Digit | Multiplier | Tolerance |
| Black | 0 | 1 | – |
| Brown | 1 | 10 | ±1% |
| Red | 2 | 100 | ±2% |
| Orange | 3 | 1000 | – |
| Yellow | 4 | 10000 | – |
| Green | 5 | 100,000 | ±0.5% |
| Blue | 6 | 1,000,000 | ±0.25% |
| Violet | 7 | 10,000,000 | ±0.1% |
| Gray | 8 | 100,000,000 | ±0.05% |
| White | 9 | 1,000,000,000 | – |
| Gold | – | 0.1 | ±5% |
| Silver | – | 0.01 | ±10% |
- Read the color band from left to right. Assign the corresponding digits to the color from the above table. The first two or three bands represent significant figures, while the last band indicates the multiplier.
- Calculate the capacitance value by combining the digits and multiplier. Multiply the significant figure digits by the multiplier digit.
For example, if you have a capacitor with color bands brown, black, red, and gold.
Brown: 1 (first digit)
Black: 0 (second digit)
Red: 2 (multiplier of 100)
Gold: 0.1 (5% tolerance)
So the capacitor value is 10 x 100 = 1,000 picofarads (pF) with a tolerance of ±5%.
By referring to the color code chart and following these steps, you can accurately determine the capacitance value of a capacitor through the color coding system.
Conclusion
A Capacitor is an electronic component that stores energy. It has two conductive plates and insulating material between them.
There are various types of capacitors and different methods are used to show the capacitance value. The larger capacitors have already a capacitance value printed on them and smaller capacitors can either have a digit code or a color code.
Most of the capacitors have digits that represent capacitance. The first two digits are digits of capacitance and the third digit is a multiplier.
The color code is also used to represent the capacitance value. Four or five bands are printed on the capacitor. The two or three bands show the digits and the last band is multiplier.
This was all about how to read a capacitor value, I hope it will help you read the capacitor’s capacitance.
Thank you and stay blessed…
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