Result
Result reflects the current submitted inputs.
- Risk A
- Reviewed 2026-05-26
- 2 sources
- This MVP decodes common 4-band and 5-band fixed resistor color codes only.
- Color inputs are assumed to be read correctly by the user; photo recognition and orientation detection are out of scope.
- Tolerance is treated as a symmetric percent range around nominal resistance.
- SMD codes, six-band temperature coefficient, series/parallel networks, power ratings, and electrical safety advice are out of scope.
- Intermediate values are not rounded; raw outputs are rounded to 10 decimal places for stability.
Accuracy notes
- Risk level
- A
- Reviewed
- 2026-05-26
- Sources
- 2
- Primary result
- Resistance
Formula logic is kept in a pure calculator module with fixtures, source notes, and page-visible assumptions.
What the result means
The ohm value is the resistor's nominal resistance, and the tolerance tells you how far the real value may stray from it. A 1,000-ohm resistor at 5% tolerance can measure anywhere from 950 to 1,050 ohms. In a circuit, series resistors raise total resistance while parallel resistors lower it, which is how designers hit a target value from standard parts.
Use the result this way
- Start with Resistance, then use supporting outputs for context.
- Verify Band count, First digit band, and Second digit band before copying the result.
- Check the formula, example, and assumptions before reusing the answer.
User job
How to use this calculator
Use Resistor Calculator when you need resistance, then use tolerance and minimum resistance to check the context for unit checks, engineering notes, recipes, travel, shopping, and measurement cleanup.
Best for
- Converting compatible units
- Auditing the factor used for a repeated conversion
- Reviewing a default example before entering your own band count and first digit band.
Check before relying
- Make sure the source and target units measure the same kind of quantity.
- This MVP decodes common 4-band and 5-band fixed resistor color codes only.
- Color inputs are assumed to be read correctly by the user; photo recognition and orientation detection are out of scope.
- Source context: International Electrotechnical Commission, reviewed 2026-06-16.
Next useful step
- Scientific Notation CalculatorUse next when your task shifts from Resistor Calculator to Scientific Notation Calculator.
- Binary CalculatorUse next when your task shifts from Resistor Calculator to Binary Calculator.
- Scientific CalculatorUse next when your task shifts from Resistor Calculator to Scientific Calculator.
Formula
Color-code value: the first bands give significant digits, the next band is the multiplier (power of ten), and the last band is the tolerance. For a 4-band resistor, value = (digit1 digit2) x 10^multiplier, with a tolerance band. Series resistance: R_total = R1 + R2 + R3 + ... Parallel resistance: 1 / R_total = 1/R1 + 1/R2 + 1/R3 + ..., so two equal resistors in parallel give half the value.
- Color-to-digit code: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. These set the significant digits and the multiplier.
- Multiplier band uses the same colors as powers of ten: black x1, brown x10, red x100, orange x1k, and so on. Gold is x0.1 and silver is x0.01 for small values.
- Tolerance band: brown 1%, red 2%, gold 5%, silver 10%, or no band means 20%. Gold and silver in the last position almost always indicate tolerance.
- Series resistors add: R_total = R1 + R2 + ... Parallel resistors combine by reciprocals: 1/R_total = 1/R1 + 1/R2 + ..., and the total is always smaller than the smallest resistor.
- 4-band resistors have two significant digits; 5-band (and 6-band) resistors add a third digit for tighter precision, common in higher-accuracy parts.
Inputs
For the color code, select the color of each band in order from left to right. A 4-band resistor has two digit bands, one multiplier, and one tolerance band; a 5-band resistor adds a third digit for higher precision. For series or parallel, enter each resistance value; series adds them up, while parallel always gives a total lower than the smallest single resistor.
Example
A 4-band resistor with bands brown, black, red, gold reads as digits 1 and 0, multiplier 10^2, so 10 x 100 = 1,000 ohms (1 kilohm) with 5% tolerance. Two 100-ohm resistors in series make 200 ohms; the same two in parallel make 50 ohms, since 1 / (1/100 + 1/100) = 50.
FAQ
How do you read a resistor color code?
Read the bands left to right. The first two (or three for 5-band) are significant digits, the next band is the multiplier (power of ten), and the last band is the tolerance. Brown-black-red-gold is 10 x 100 = 1,000 ohms at 5%.
What is the resistor color code chart?
Each color is a digit: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. The same colors act as multipliers (powers of ten) in the multiplier band.
How do you calculate resistors in parallel?
Add the reciprocals: 1/R_total = 1/R1 + 1/R2 + ... and invert. Two 100-ohm resistors in parallel give 1 / (1/100 + 1/100) = 50 ohms. The total is always less than the smallest resistor.
How do you calculate resistors in series?
Add the values: R_total = R1 + R2 + R3 + ... Three resistors of 100, 220, and 330 ohms in series total 650 ohms. Series resistance is always higher than any single resistor.
What does the gold band on a resistor mean?
A gold band in the last position means 5% tolerance; silver means 10%. In the multiplier position, gold means multiply by 0.1 and silver by 0.01, used for resistors below 10 ohms.
What is the difference between 4-band and 5-band resistors?
A 4-band resistor has two digit bands, a multiplier, and a tolerance band. A 5-band resistor adds a third significant digit for higher precision, so it can specify values more exactly, common in precision components.
Sources
Last reviewed: 2026-05-26
- officialReviewed 2026-06-16IEC 60062: Marking codes for resistors and capacitorsInternational Electrotechnical Commission. International standard defining the resistor color band marking system and tolerance codes.
- academicReviewed 2026-06-16Resistor Color Codes and Series/Parallel CombinationsAll About Circuits. Reference for resistor color decoding and series and parallel resistance formulas.
Disclaimer
Color-code results assume standard IEC band conventions; always verify a resistor's value with a multimeter for critical circuits. Series and parallel results are ideal calculations that ignore real-world tolerances and temperature effects.