Resistor Color Code Calculator
Decode resistor color bands, calculate tolerance range, convert a resistance value back into color bands, or decode common SMD and EIA-96 resistor markings.
Calculator is for informational purposes only. Terms and Conditions
Choose calculator mode
Decode bands, find color bands from a resistor value, or decode SMD resistor markings.
Enter the known values
Only the inputs needed for the selected resistor mode are shown.
Visual Check
Use the resistor preview to verify band order, tolerance, and the decoded value.
Solution
Live result, quick checks, warnings, and full solution steps.
Quick checks
- Tolerance range—
Show solution steps See band meanings, equation, tolerance range, and assumptions
- Select resistor colors to see the full solution steps and checks.
Source, Standards, and Assumptions
Calculation basis, constants, assumptions, and limitations.
This calculator uses the standard resistor color-code method for significant digits, multiplier, tolerance, and temperature coefficient.
- Color-band decoding identifies nominal resistance only; it does not determine resistor wattage, voltage rating, failure condition, or circuit suitability.
On this page
Calculator Guide
How to Use the Resistor Color Code Calculator
The Resistor Color Code Calculator above decodes resistor bands into resistance, tolerance, and allowable range. Select the number of bands, choose the colors from left to right, and read the nominal value in ohms, kilohms, or megohms. You can also use reverse lookup to find color bands from a known resistor value or decode common SMD resistor markings.
This guide explains how resistor color codes work, how to read 3-band, 4-band, 5-band, and 6-band resistors, how tolerance changes the expected measurement range, and when to verify the result with a multimeter or datasheet.
Quick Answer
To read a resistor color code, hold the tolerance band on the right and read the bands from left to right. For a common 4-band resistor, the first two bands are significant digits, the third band is the multiplier, and the fourth band is tolerance. The basic calculation is \(R=\text{digits}\times\text{multiplier}\).
Do not rely on color code alone when…
Do not rely only on color bands if the resistor is burnt, faded, still installed in a circuit that affects the reading, or used in a power-critical design. Color code identifies nominal resistance and tolerance; it does not prove wattage, voltage rating, temperature rating, damage condition, or suitability for the circuit.
Inputs and Outputs Used by the Calculator
The calculator input depends on the selected mode. Color-band mode uses band colors, reverse mode uses a known resistance value, and SMD mode uses the printed marking on a surface-mount resistor.
| Type | Value | What It Means | Common Unit |
|---|---|---|---|
| Input | Band Count | Selects whether the resistor has 3, 4, 5, or 6 color bands. | bands |
| Input | Digit Bands | Color bands that form the significant digits of the resistor value. | color |
| Input | Multiplier Band | Color band that multiplies the significant digits by a power of ten or fractional multiplier. | × factor |
| Input | Tolerance Band | Allowed percentage variation from the nominal resistance value. | % |
| Input | Temperature Coefficient | Sixth band on 6-band resistors that shows resistance drift with temperature. | ppm/°C |
| Input | SMD Code | Printed marking on a chip resistor, such as 472, 1001, 4R7, or 01A. | marking |
| Output | Resistance | Nominal decoded resistor value. | Ω, kΩ, MΩ |
| Output | Tolerance Range | Minimum and maximum resistance expected from the tolerance band. | Ω, kΩ, MΩ |
Formula Used by the Calculator
The main resistor color code formula multiplies the significant digits by the multiplier band. Tolerance is then applied separately to find the allowable minimum and maximum value.
Main Color Code Formula
\(R\) is resistance, \(D\) is the significant digit number formed by the digit bands, and \(M\) is the multiplier.
Tolerance Range
\(T\) is tolerance in percent. A 10 kΩ resistor with ±5% tolerance may measure from 9.5 kΩ to 10.5 kΩ.
Temperature Drift for 6-Band Resistors
TCR is temperature coefficient in ppm/°C and \(\Delta T\) is the temperature change in °C.
SMD 3-Digit Code
For example, 472 means \(47\times10^2=4{,}700\,\Omega=4.7\,k\Omega\).
What the Variables Mean
Each variable describes one part of the color-code calculation. Most wrong answers come from reading the multiplier or tolerance band in the wrong position.
| Symbol | Meaning | How to Use It |
|---|---|---|
| \(R\) | Nominal resistance value. | Read in Ω, kΩ, or MΩ after applying the multiplier. |
| \(D\) | Significant digit number. | Use two digits for most 3-band and 4-band resistors; use three digits for most 5-band and 6-band resistors. |
| \(M\) | Multiplier from the multiplier color band. | Examples: red = ×100, orange = ×1,000, gold = ×0.1, silver = ×0.01. |
| \(T\) | Tolerance percentage. | Gold is ±5%, silver is ±10%, and no tolerance band is commonly treated as ±20%. |
| \(R_{\min}\) | Lowest expected resistance within tolerance. | Use this to compare against a low multimeter reading. |
| \(R_{\max}\) | Highest expected resistance within tolerance. | Use this to compare against a high multimeter reading. |
| TCR | Temperature coefficient of resistance. | Used on 6-band resistors to estimate drift in ppm/°C. |
How to Use the Calculator
Start by matching the calculator mode to the resistor or marking you have. Then enter the colors or code exactly as they appear.
Choose the mode
Use color-band mode for axial resistors, reverse mode when you know the resistance and need the colors, or SMD mode for chip resistor markings.
Find the reading direction
Place the tolerance band on the right when possible. The first band is usually closest to one end of the resistor body.
Select each band color
Enter the bands from left to right. For 5-band and 6-band resistors, the first three bands are usually significant digits.
Review resistance and tolerance
Use the nominal value for circuit calculations and the tolerance range to judge whether a measured value is reasonable.
Which Direction Do You Read a Resistor?
Start from the side where the first color band is closest to the resistor lead. If one end has a gold or silver band, hold that band on the right because it is usually the tolerance band. If there is a larger gap before the final band, that final band is also likely the tolerance band.
When direction is still unclear
If both directions produce possible-looking values, compare the result to the circuit function, check the schematic if available, or measure the resistor out of circuit. A burnt or faded resistor should not be trusted by color interpretation alone.
How to Interpret the Result
The decoded value is the nominal resistance. The actual part may measure higher or lower depending on tolerance, temperature, age, and measurement conditions.
| Result Pattern | What It Means | What to Do Next |
|---|---|---|
| Measured value is inside tolerance range | The resistor value is consistent with the color code. | Use the nominal value for basic calculations, or use measured value for troubleshooting. |
| Measured value is slightly outside range | The part may be damaged, overheated, old, or affected by surrounding circuit paths. | Measure out of circuit or compare with a known-good part. |
| Color code gives a very different value | The resistor may be read backward or the multiplier band may be misidentified. | Check the tolerance-band side and re-enter colors from the opposite direction. |
| 3-band resistor result has wide range | No tolerance band is commonly treated as ±20%. | Do not use it where tight accuracy is required. |
| SMD code does not match expected value | The marking may use EIA-96, R notation, zero-ohm notation, or a manufacturer-specific code. | Check package marking rules or verify with a meter. |
What to do with the result
Use the decoded resistance in circuit checks such as current limiting, voltage dividers, pull-up/pull-down resistors, RC timing, and power dissipation estimates. For component replacement, match resistance, tolerance, wattage, package size, and voltage rating.
What changes the result most?
The multiplier band changes the result the most because it shifts the value by powers of ten. Misreading red as orange changes ×100 to ×1,000, which turns 4.7 kΩ into 47 kΩ. Reading direction is the next biggest issue because it can swap the multiplier and tolerance bands.
Quick sanity check
If gold or silver appears at one end, it is usually the tolerance band and should be placed on the right. If the decoded value seems wildly wrong, reverse the reading direction and check whether the final band is actually the tolerance band.
Measured-value example
For a 4.7 kΩ ±5% resistor, a meter reading of 4.82 kΩ is reasonable because it falls between 4.465 kΩ and 4.935 kΩ. A reading of 3.9 kΩ is suspicious unless the resistor is still connected to other circuit paths that are affecting the measurement.
Input Quality Checklist
Use this checklist before trusting the decoded result. Resistor color codes are simple, but faded colors and wrong band direction can create convincing errors.
Confirm band count
Count only actual color bands. Do not count the resistor body color or end cap color as a band.
Find the tolerance side
Gold, silver, and isolated end bands usually belong on the right side.
Check similar colors
Brown, red, and orange can be difficult to distinguish on old or overheated resistors.
Verify in circuit conditions
A multimeter reading can be wrong if the resistor is still connected to parallel circuit paths.
Step-by-Step Worked Example
A common use case is decoding a 4-band resistor from its visible color bands. This example uses Yellow Violet Red Gold.
Formula
Substitution
Tolerance Range
Result
Yellow Violet Red Gold is a 4.7 kΩ ±5% resistor. A measured value from about 4.465 kΩ to 4.935 kΩ is within tolerance.
Reasonableness check
The result is reasonable because yellow-violet forms 47 and red multiplies by 100. Since gold is the tolerance band, it belongs at the end rather than in the digit position.
Resistor Band Diagram
The band positions determine what each color means. The same color can represent a digit, multiplier, tolerance, or temperature coefficient depending on where it appears.
| Resistor Type | Band 1 | Band 2 | Band 3 | Band 4 | Band 5 | Band 6 |
|---|---|---|---|---|---|---|
| 3-band | Digit | Digit | Multiplier | None = ±20% | — | — |
| 4-band | Digit | Digit | Multiplier | Tolerance | — | — |
| 5-band | Digit | Digit | Digit | Multiplier | Tolerance | — |
| 6-band | Digit | Digit | Digit | Multiplier | Tolerance | ppm/°C |
How this diagram helps
Use the band count to identify which colors are digits, multiplier, tolerance, and temperature coefficient. This avoids the most common error: treating the tolerance band as part of the resistance value.
Reference Values and Color Code Chart
The resistor color code chart maps each color to a digit, multiplier, tolerance, and sometimes temperature coefficient. The role depends on the band position.
| Color | Digit | Multiplier | Tolerance | Temperature Coefficient |
|---|---|---|---|---|
| Black | 0 | ×1 | — | — |
| Brown | 1 | ×10 | ±1% | 100 ppm/°C |
| Red | 2 | ×100 | ±2% | 50 ppm/°C |
| Orange | 3 | ×1,000 | — | 15 ppm/°C |
| Yellow | 4 | ×10,000 | — | 25 ppm/°C |
| Green | 5 | ×100,000 | ±0.5% | — |
| Blue | 6 | ×1,000,000 | ±0.25% | 10 ppm/°C |
| Violet | 7 | ×10,000,000 | ±0.1% | 5 ppm/°C |
| Gray | 8 | ×100,000,000 | ±0.05% | — |
| White | 9 | ×1,000,000,000 | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
| None | — | — | ±20% | — |
| Tolerance Band | Tolerance | What It Usually Means |
|---|---|---|
| Brown | ±1% | Precision resistor tolerance for tighter circuits. |
| Red | ±2% | Tighter than general-purpose ±5% resistors. |
| Green | ±0.5% | Precision resistor tolerance. |
| Blue | ±0.25% | Higher precision tolerance band. |
| Violet | ±0.1% | High precision tolerance band. |
| Gray | ±0.05% | Very tight tolerance band. |
| Gold | ±5% | Very common general-purpose resistor tolerance. |
| Silver | ±10% | Wider tolerance for less precise applications. |
| No band | ±20% | Common assumption for 3-band or older basic resistors. |
Common Resistor Values and Practical Ranges
Many electronics tasks use common resistor values such as 220 Ω, 1 kΩ, 4.7 kΩ, 10 kΩ, and 100 kΩ. These values are common because standard resistor series repeat preferred numbers across decades.
| Resistance | 4-Band Colors | Calculation | Common Use |
|---|---|---|---|
| 100 Ω | Brown Black Brown Gold | 10 × 10 | Small current limiting, signal damping |
| 220 Ω | Red Red Brown Gold | 22 × 10 | LED current limiting, general electronics |
| 330 Ω | Orange Orange Brown Gold | 33 × 10 | LEDs, logic circuits |
| 470 Ω | Yellow Violet Brown Gold | 47 × 10 | Pull networks, small signal circuits |
| 1 kΩ | Brown Black Red Gold | 10 × 100 | General pull-up/pull-down values |
| 4.7 kΩ | Yellow Violet Red Gold | 47 × 100 | Pull-up resistors, sensor circuits |
| 10 kΩ | Brown Black Orange Gold | 10 × 1,000 | Common pull-up/pull-down and input bias value |
| 47 kΩ | Yellow Violet Orange Gold | 47 × 1,000 | Biasing and signal input networks |
| 100 kΩ | Brown Black Yellow Gold | 10 × 10,000 | High impedance bias and sensing circuits |
| 1 MΩ | Brown Black Green Gold | 10 × 100,000 | High impedance inputs and leakage paths |
Practical design note
A correct resistance value is not enough for final component selection. Always check power dissipation with \(P=I^2R\) or \(P=V^2/R\), and confirm package size, wattage, tolerance, voltage rating, and temperature rating.
Units and Conversion Notes
Resistor values are usually shown in ohms, kilohms, or megohms. The calculator may display the most readable unit automatically, but the base unit is always ohms.
| Unit | Meaning | Conversion | Example |
|---|---|---|---|
| Ω | Ohms | Base unit | 470 Ω |
| kΩ | Kilohms | \(1\,k\Omega=1{,}000\,\Omega\) | 4.7 kΩ = 4,700 Ω |
| MΩ | Megohms | \(1\,M\Omega=1{,}000{,}000\,\Omega\) | 1 MΩ = 1,000,000 Ω |
| ppm/°C | Temperature coefficient | Parts per million per degree Celsius | 100 ppm/°C changes about 0.01% per °C |
Most common unit mistake
The biggest unit mistake is confusing 4.7 kΩ with 47 kΩ or 470 Ω. In color-code terms, that usually means the multiplier band was read incorrectly.
3-Band vs 4-Band vs 5-Band vs 6-Band Resistors
The number of bands tells you how many digits to use and whether tolerance or temperature coefficient is included.
| Type | Band Pattern | Best For | Main Caution |
|---|---|---|---|
| 3-band | Digit, digit, multiplier | Older or low-precision resistors | No tolerance band is commonly treated as ±20%. |
| 4-band | Digit, digit, multiplier, tolerance | General electronics and common resistor values | Gold/silver at the end is tolerance, not a digit. |
| 5-band | Digit, digit, digit, multiplier, tolerance | Precision resistors with three significant digits | Do not use the 4-band method on a normal 5-band precision resistor. |
| 6-band | Digit, digit, digit, multiplier, tolerance, TCR | Precision resistors where temperature drift matters | The sixth band is ppm/°C, not another tolerance band. |
| SMD marking | Printed code such as 472, 4R7, or 01A | Surface-mount resistors | Use SMD decoding rules, not color-band rules. |
5-band exception caution
Most modern 5-band resistors use three significant digits, a multiplier, and a tolerance band. If an unusual older resistor appears to use gold or silver in a nonstandard position, verify the value with a datasheet or multimeter instead of relying on color interpretation alone.
Common Mistakes When Reading Resistor Codes
Most resistor color code mistakes are not math errors. They happen because the bands are read in the wrong direction, colors are confused, or the resistor is assumed to have ratings that the color bands do not show.
Common Mistakes
- Reading the resistor backward and swapping multiplier with tolerance.
- Confusing brown, red, and orange on old or overheated parts.
- Assuming gold and silver are significant digit colors.
- Using a 4-band method on a 5-band precision resistor.
- Assuming color bands show wattage or voltage rating.
- Measuring a resistor in circuit without considering parallel paths.
Better Practice
- Place the tolerance band on the right before decoding.
- Use the calculator visual to verify band order.
- Check the tolerance range before rejecting a measured part.
- Use a multimeter when the colors are faded or damaged.
- Verify wattage and package rating from size or datasheet.
- Lift one lead when a circuit reading does not make sense.
Troubleshooting Unexpected Results
If the calculator result looks wrong, check band direction first. Then check whether the resistor is color-banded, SMD-marked, damaged, or still connected to the circuit.
| Problem | Likely Cause | Fix |
|---|---|---|
| Value is off by 10× or 100× | Multiplier band was misread. | Check whether the multiplier is brown, red, orange, or yellow. |
| Gold or silver appears near the start | The resistor may be reversed. | Put gold or silver on the right and decode again. |
| Measured value is lower than expected | Parallel circuit paths may affect the meter reading. | Remove power and lift one resistor lead before measuring. |
| Colors are hard to distinguish | Heat, age, dirt, or lighting may distort the color. | Clean the part, improve lighting, or verify with a multimeter. |
| SMD code is not decoded | The marking may be manufacturer-specific or damaged. | Check the datasheet or measure the part directly. |
| SMD Code | Decoding Rule | Resistance | Note |
|---|---|---|---|
| 472 | \(47\times10^2\) | 4.7 kΩ | Common 3-digit SMD format. |
| 103 | \(10\times10^3\) | 10 kΩ | Common 3-digit SMD format. |
| 1001 | \(100\times10^1\) | 1 kΩ | Common 4-digit SMD format. |
| 4R7 | R marks the decimal point | 4.7 Ω | Used for low-value resistors. |
| 47R | R after digits means ohms | 47 Ω | Another low-value marking style. |
| 0R0 | Zero-ohm notation | 0 Ω | Usually a jumper, not a normal resistor value. |
| 01A | EIA-96 value code 01 with multiplier A | 100 Ω | EIA-96 code for precision SMD resistors. |
SMD quick reference
For SMD resistors, 472 means \(47\times10^2=4.7\,k\Omega\), 1001 means \(100\times10^1=1\,k\Omega\), 4R7 means 4.7 Ω, 47R means 47 Ω, and 0R0 usually means a zero-ohm jumper.
Assumptions, Sources, and Limitations
This calculator is intended for resistor identification, education, repair support, and quick circuit checks. It follows standard resistor marking conventions for color bands and common SMD codes.
Nominal Value Only
The color code gives nominal resistance and tolerance, not the exact measured value of the individual part.
No Wattage Rating
Color bands do not identify resistor wattage. Wattage depends on resistor size, material, construction, and manufacturer rating.
SMD Limit
Common SMD codes can be decoded, but manufacturer-specific, damaged, or ambiguous markings should be verified with a datasheet or meter.
Final Design Note
For final circuit design, verify resistance, tolerance, wattage, voltage rating, temperature range, derating, and datasheet requirements.
Reference source
This article follows the standard color-band interpretation used for IEC 60062-style resistor markings. TE Connectivity’s resistor color code guide explains 3-, 4-, 5-, and 6-band markings, reading direction, and tolerance-band spacing: TE Connectivity resistor color code guide.
Glossary of Terms
These terms help clarify what the calculator output means and how to use the resistor value correctly.
Resistance
Opposition to electric current flow, measured in ohms.
Multiplier Band
The color band that multiplies the significant digits by a power of ten or fractional factor.
Tolerance
The allowed percent variation from the nominal resistance value.
Temperature Coefficient
The amount resistance changes with temperature, usually shown in ppm/°C on 6-band resistors.
SMD Resistor
A surface-mount resistor that usually uses printed markings instead of color bands.
EIA-96 Code
A three-character SMD code using two digits for a value code and one letter for the multiplier. For example, 01A commonly represents \(100\times1=100\,\Omega\).
Frequently Asked Questions
What is the resistor color code for 1k?
The common 4-band color code for a 1 kΩ resistor is Brown Black Red Gold. Brown and black form 10, red is the ×100 multiplier, and gold means ±5% tolerance.
What is the resistor color code for 10k?
The common 4-band color code for a 10 kΩ resistor is Brown Black Orange Gold. Brown and black form 10, orange is the ×1,000 multiplier, and gold means ±5% tolerance.
Which way do you read resistor color bands?
Read resistor color bands from the side where the first band is closest to the lead. The tolerance band is usually spaced farther away and is commonly gold, silver, brown, red, green, blue, violet, or gray.
What does a gold band mean on a resistor?
A gold band usually means ±5% tolerance when it is the final band. If gold is used as a multiplier band, it means ×0.1.
What does 472 mean on an SMD resistor?
A 472 SMD resistor marking means \(47\times10^2\) ohms, which equals 4,700 Ω or 4.7 kΩ.
Does resistor color code show wattage?
No. Resistor color bands identify nominal resistance, tolerance, and sometimes temperature coefficient. Wattage depends on the resistor body size, construction, material, manufacturer rating, and datasheet.