Quick answer
On a 4-band resistor, the first two bands are digits, the third is the multiplier and the fourth is the tolerance. Yellow, violet, red, gold reads 47 × 100 = 4,700 Ω ± 5%, shown as 4.7 kΩ with a range of 4.465 to 4.935 kΩ.
Choose the band count and the colour of each band. The calculator returns the resistance, the tolerance and the minimum and maximum values the part should fall between within its rated tolerance. It decodes a resistor's colour code (the colored bands) into ohms.
Related tools: Parallel Resistor Calculator: Equivalent resistance of resistors in parallel and in series. Ohm's Law Calculator: Solve voltage, current or resistance.
How to use the Resistor Color Code Calculator
- Choose bands: 4-band and 5-band.
- Choose band 1: Black, Brown, Red, Orange, Yellow and Green and 4 more.
- Choose band 2: Black, Brown, Red, Orange, Yellow and Green and 4 more.
- Optionally, choose band 3 (5-band only): Black, Brown, Red, Orange, Yellow and Green and 4 more.
- Choose multiplier: Black, Brown, Red, Orange, Yellow and Green and 6 more.
- Choose tolerance: Brown (±1%), Red (±2%), Green (±0.5%), Blue (±0.25%), Violet (±0.1%) and Gray (±0.05%) and 2 more.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Bands | Choose one: 4-band; 5-band | Starts at 4-band |
| Band 1 | Choose one: Black; Brown; Red; Orange; Yellow; Green; Blue; Violet; … | Starts at Brown |
| Band 2 | Choose one: Black; Brown; Red; Orange; Yellow; Green; Blue; Violet; … | Starts at Black |
| Band 3 (5-band only) (optional) | Choose one: Black; Brown; Red; Orange; Yellow; Green; Blue; Violet; … | Starts at Black |
| Multiplier | Choose one: Black; Brown; Red; Orange; Yellow; Green; Blue; Violet; … | Starts at Red |
| Tolerance | Choose one: Brown (±1%); Red (±2%); Green (±0.5%); Blue (±0.25%); Violet (±0.1%); Gray (±0.05%); Gold (±5%); Silver (±10%) | Starts at Gold (±5%) |
Formula and method
Formula
value = (digits) × multiplier
IEEE-754 double precision; shown to the decimals indicated.
Digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. Multipliers are powers of ten (gold ×0.1, silver ×0.01).
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Bands = 4-band; Band 1 = Yellow; Band 2 = Violet; Multiplier = Red; Tolerance = Gold (±5%).
| Result | Value |
|---|---|
| Resistance | 4.7 kΩ |
| Tolerance | ±5% |
| Minimum | 4.465 kΩ |
| Maximum | 4.935 kΩ |
Example 2
Inputs: Bands = 4-band; Band 1 = Brown; Band 2 = Black; Multiplier = Orange; Tolerance = Brown (±1%).
| Result | Value |
|---|---|
| Resistance | 10 kΩ |
| Tolerance | ±1% |
| Minimum | 9.9 kΩ |
| Maximum | 10.1 kΩ |
Example 3
Inputs: Bands = 5-band; Band 1 = Red; Band 2 = Red; Multiplier = Brown; Tolerance = Red (±2%); Band 3 (5-band only) = Black.
| Result | Value |
|---|---|
| Resistance | 2.2 kΩ |
| Tolerance | ±2% |
| Minimum | 2.156 kΩ |
| Maximum | 2.244 kΩ |
The first line is the headline result (resistance). Below it the resistor Color Code Calculator lists tolerance, minimum and maximum, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Reading the bands
Hold the resistor with the tolerance band (gold or silver) on the right. Digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. The multiplier is 10 raised to the colour's number, so red is ×100.
Tolerance range
A ± 5% tolerance means the real value lies between 95% and 105% of nominal: 4,700 × 0.95 = 4,465 Ω and 4,700 × 1.05 = 4,935 Ω. For precision circuits choose 1% or tighter parts, which have an extra digit band (5-band).
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Band 1: entering "bad" shows "Choose a valid band 1." beside that field and no result.
- Tolerance: entering "none" shows "Choose a valid tolerance." beside that field and no result.
Choosing between the Resistor Color Code Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Parallel Resistor Calculator](/engineering/parallel-resistor-calculator/) | resistances | Parallel resistance |
| [Ohm's Law Calculator](/engineering/ohm-s-law-calculator/) | Current | |
| [Voltage Drop Calculator](/engineering/voltage-drop-calculator/) | current, one-way length and wire gauge | Voltage drop |
| [Gear Ratio Calculator](/engineering/gear-ratio-calculator/) | driving gear teeth and driven gear teeth | Gear ratio |
| [Power-to-Weight Ratio Calculator](/engineering/power-to-weight-ratio/) | power, power unit and weight | Power-to-weight |
Assumptions and limitations
- Read from the end with the tolerance band separated
Use results as engineering estimates and check them against the governing standards, safety factors and a qualified engineer's judgement before relying on them.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for band 1 and tolerance to confirm this.
Frequently asked questions
What does the gold band mean?
As a fourth band it means ±5%; as a multiplier it means ×0.1.
How do I tell which end to start from?
The tolerance band is usually spaced apart; start from the end opposite it.
What if the colours are hard to tell apart?
Measure the resistor with a multimeter, outside the circuit.
What does the Resistor Color Code Calculator calculate?
Resistance value and tolerance from color bands. It returns Resistance, Tolerance, Minimum and Maximum.
What formula does the Resistor Color Code Calculator use?
value = (digits) × multiplier. Digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9.
What do I need to enter in the resistor Color Code Calculator?
You enter Bands, Band 1, Band 2, Multiplier and Tolerance. Optional: Band 3 (5-band only).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Read from the end with the tolerance band separated.
What does the “Bands” option change?
It sets how the resistor Color Code is worked out. The choices are 4-band and 5-band.
What is an example of a resistor Color Code result?
With bands 4-band, band 1 Yellow, band 2 Violet, multiplier Red and tolerance Gold (±5%), the resistance is 4.7 kΩ.
Where does the method come from?
The method follows: IEC 60062 resistor color code.
Can I rely on this calculator for a decision?
Use results as engineering estimates and check them against the governing standards, safety factors and a qualified engineer's judgement before relying on them. For this calculator in particular: Read from the end with the tolerance band separated.
Related calculators
- Parallel Resistor Calculator — Equivalent resistance of resistors in parallel and in series.
- Ohm's Law Calculator — Solve voltage, current or resistance.
- Gear Ratio Calculator — Gear ratio, output speed and torque multiplication.
- Power-to-Weight Ratio Calculator — Power per unit weight of a vehicle.
- CFM Calculator — Airflow in cubic feet per minute from duct velocity or air changes.
Sources
- IEC 60062 resistor color code
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.