Resistor Calculator
Calculate resistor values using color bands, find the right resistor for your circuit, and learn how to read resistor color codes with our easy-to-use calculator.
Resistor Color Code Calculator
Use this calculator to determine resistance value and color code
Brown
Black
Red
Gold
Reference Table
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
Black | 0 | ×1 | - |
Brown | 1 | ×10 | ±1% |
Red | 2 | ×100 | ±2% |
Orange | 3 | ×1000 | ±3% |
Yellow | 4 | ×10000 | ±4% |
Green | 5 | ×100000 | ±0.5% |
Blue | 6 | ×1000000 | ±0.25% |
Violet | 7 | ×10000000 | ±0.1% |
Grey | 8 | ×100000000 | ±0.05% |
White | 9 | ×1000000000 | - |
Gold | - | ×0.1 | ±5% |
Silver | - | ×0.01 | ±10% |
None | - | - | ±20% |
Resistor Value
Resistor Information
What is a Resistor?
A resistor is an electronic component that limits the flow of electric current. They are used in circuits to control current and voltage.
The unit of resistance is the Ohm (Ω), named after the German physicist Georg Simon Ohm.
Ohm's Law
$$R = \frac{V}{I}$$
Ohm's Law describes the relationship between voltage, current, and resistance:
V = I × R, where V is voltage (Volts), I is current (Amperes), and R is resistance (Ohms).
How to Use the Resistor Calculator
Our resistor calculator offers three different functions to help you with resistance-related calculations.
Color Code Calculator
- Select the number of bands on the resistor (3, 4, 5, or 6).
- Select the color for each band.
- Click the "Calculate Resistance" button.
- View the calculated results, including resistance value, tolerance range, and standard E-series values.
Parallel Resistor Calculator
- Enter the resistor values in the parallel circuit, separated by commas.
- Click the "Calculate" button to see the total resistance value.
Series Resistor Calculator
- Enter the resistor values in the series circuit, separated by commas.
- Click the "Calculate" button to see the total resistance value.
Resistor Color Code Chart
Resistor color codes are a standardized way to represent the resistance value, tolerance, and temperature coefficient of resistors. Here is detailed information on resistor color codes.
Band Types
- 3-Band Resistor: Two digits + Multiplier
- 4-Band Resistor: Two digits + Multiplier + Tolerance
- 5-Band Resistor: Three digits + Multiplier + Tolerance
- 6-Band Resistor: Three digits + Multiplier + Tolerance + Temperature Coefficient
Color Code Table
The table below shows the corresponding digit, multiplier, and tolerance values for various colors.
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
Black | 0 | ×1 (10⁰) | - |
Brown | 1 | ×10 (10¹) | ±1% |
Red | 2 | ×100 (10²) | ±2% |
Orange | 3 | ×1,000 (10³) | - |
Yellow | 4 | ×10,000 (10⁴) | - |
Green | 5 | ×100,000 (10⁵) | ±0.5% |
Blue | 6 | ×1,000,000 (10⁶) | ±0.25% |
Violet | 7 | ×10,000,000 (10⁷) | ±0.1% |
Grey | 8 | ×100,000,000 (10⁸) | ±0.05% |
White | 9 | ×1,000,000,000 (10⁹) | - |
Gold | - | ×0.1 (10⁻¹) | ±5% |
Silver | - | ×0.01 (10⁻²) | ±10% |
None | - | - | ±20% |
Mnemonic: Black Brown Red Orange Yellow Green Blue Violet Grey White (0-9)
Applications
Resistors have a wide range of applications in electronic circuits. Here are some common scenarios for resistor use.
Common Application Examples
- Current Limiting: To limit the amount of current in a circuit.
- Voltage Division: To create different voltage levels.
- Pull-up/Pull-down: To ensure a stable state for digital signals.
- Load: To act as a load element in a circuit.
Parallel and Series Applications
By connecting resistors in parallel or series, specific resistance values and power handling capabilities can be achieved.
Parallel Connection: Total resistance is less than any individual resistor; suitable for reducing total resistance or increasing power handling capacity.
$$\frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + ... + \frac{1}{R_n}$$
Series Connection: Total resistance is the sum of all resistors; suitable for increasing total resistance or distributing voltage.
$$R_{total} = R_1 + R_2 + ... + R_n$$
Frequently Asked Questions
How do I read resistor color codes?
Read the bands from left to right. The first two or three bands represent digits, followed by the multiplier, tolerance, and temperature coefficient (if present). Refer to the color code chart above for details.
Why do resistors have different power ratings?
A resistor's power rating indicates the maximum power it can safely dissipate. Exceeding this value can cause the resistor to overheat and potentially be damaged. Common power ratings include 1/8W, 1/4W, 1/2W, 1W, 2W, etc.
What are E-series resistor values?
The E-series are standardized series of resistor values, such as E12 (±10% tolerance), E24 (±5% tolerance), and E96 (±1% tolerance). These series provide a set of discrete standard values covering the entire resistance range.
How do I choose the right resistor?
When selecting a resistor, consider the resistance value, power rating, tolerance requirements, and temperature coefficient. Choose parameters appropriate for the specific needs of your circuit.
Why do some resistors not have color bands?
Some resistors, especially Surface Mount Devices (SMDs) and high-power resistors, use numerical or alphabetical codes instead of color bands to mark their values. These codes follow different marking systems.