What is the four-band code for 100 ohms?

Brown, black, brown, followed by the tolerance band, commonly gold for plus or minus 5 percent.

Does resistor wattage change the color code?

No. Wattage changes power handling and usually physical size, not the resistance color bands.

Resistor Color Code Calculator: 3, 4, 5 & 6 Bands

Electronics visual tool

Decode or Build Any Resistor Color Code

Decode 3-, 4-, 5- or 6-band resistors, or enter an ohmic value and build the correct bands. The oversized resistor drawing labels every band so a 100-ohm, 100-kilohm or custom resistor can be understood at a glance.

Choose how you want to calculate

Decode color bands Build bands from resistance

Number of bands

Band 1 — first digit Band 2 — second digit Band 3 — multiplier Band 4 — tolerance

Selection and purchasing details

Preferred-value series Power rating Display unit

The wattage changes the physical size and power handling of a resistor, not the color bands for its resistance value.

Large labelled resistor

Resistance result

100-ohm resistor color code

A four-band 100-ohm resistor is brown, black, brown, gold: 1, 0, ×10 and ±5%. A five-band 100-ohm resistor is brown, black, black, black followed by its tolerance band. The same colors apply to 1/4-watt, 1/2-watt, 1-watt and 2-watt versions because wattage is not encoded by the resistance bands.

How the bands create a value

Three- and four-band resistors use two significant digits. Five- and six-band resistors use three significant digits. The multiplier shifts the decimal position, the tolerance defines the allowed manufacturing range, and a sixth band can identify the temperature coefficient in parts per million per degree Celsius.

Decode from the tolerance end

The tolerance band is commonly spaced farther from the other bands. Hold that band on the right and read from left to right. When spacing is unclear, compare both orientations against a plausible preferred value and the component’s circuit role.

Preferred E-series comparison

E6, E12, E24, E48 and E96 preferred-number series divide each decade into progressively finer preferred values. The calculator reports the closest preferred value without silently changing the resistor you entered.

Resistor color code questions

What is the four-band code for 100 Ω?

Brown, black, brown, then the tolerance color—commonly gold for ±5%.

What is the five-band code for 100 Ω?

Brown, black, black, black, then the chosen tolerance color.

Does a 2-watt 100-ohm resistor use different colors?

No. The power rating usually changes the body size and construction, while the resistance bands remain based on 100 Ω and the selected tolerance.

Can a color-code calculation replace a meter reading?

No. Heat damage, fading, unusual standards and in-circuit parallel paths can make visual identification uncertain. Confirm critical components with appropriate test equipment.

Resistor Color Code Calculator: formula-based step-by-step solution

This Resistor Color Code Calculator worked derivation uses the published default state. Its live formula panel replaces these values whenever an input, unit, mode, date, material, or scenario changes.

Governing formula or algorithm — exact production relationships:

Nearest = nearestPreferred(result.value,fields.series.value)
Max = result.value × (1+result.tolerance ÷ 100)
Min = result.value × (1-result.tolerance ÷ 100)
Display = fields.displayUnit.value
Result = mode() = 'decode'?decode(input):encode(input)
Input = collect(root)

1. Governing formulas and numeric substitution

Formula 1: Nearest = nearestPreferred(result.value,fields.series.value)
Default-value substitution: Nearest = nearestPreferred(result.(100),fields.series.(100))
Formula 2: Max = result.value × (1+result.tolerance ÷ 100)
Default-value substitution: Max = result.(100) × (1+result.tolerance ÷ 100)
Formula 3: Min = result.value × (1-result.tolerance ÷ 100)
Default-value substitution: Min = result.(100) × (1-result.tolerance ÷ 100)
Formula 4: Display = fields.displayUnit.value
Default-value substitution: Display = fields.displayUnit.(100)
Formula 5: Result = mode() = 'decode'?decode(input):encode(input)
Default-value substitution: Result = mode() = 'decode'?decode(input):encode(input) | current data: Number of bands=4; Band 1 — first digit=; Band 2 — second digit=; Band 3 — third digit=; Band 3 — multiplier=; Band 4 — tolerance=; Band 6 — temperature coefficient=; Resistance value=100
Formula 6: Input = collect(root)
Default-value substitution: Input = collect(root) | current data: Number of bands=4; Band 1 — first digit=; Band 2 — second digit=; Band 3 — third digit=; Band 3 — multiplier=; Band 4 — tolerance=; Band 6 — temperature coefficient=; Resistance value=100

2. Variables and measurement units used

Number of bands = 4
Band 1 — first digit =
Band 2 — second digit =
Band 3 — third digit =
Band 3 — multiplier =
Band 4 — tolerance =
Band 6 — temperature coefficient =
Resistance value = 100
Resistance unit = 1
Band system = 4
Tolerance = gold
Sixth-band temperature coefficient = brown
Preferred-value series = E12
Power rating = 0.25
Display unit = auto

3. Resistor Color Code Calculator final evaluation: this calculator’s production engine evaluates the substituted relationship with unrounded internal precision; its subject-specific result cards, table, and visual report the rounded final answer and verification quantities.

Resistor Color Code Calculator: formula, steps, units and verification

resistor color code calculator is designed for a transparent calculation rather than a black-box answer. Resistor Color Code Calculator: decode or build resistor color bands with a large labelled resistor, tolerance range, 100-ohm presets, temperature.

How to use the resistor color code calculator in 5 steps

Choose the required mode. Select the calculation path that matches the quantity you know and the result you need.

Enter source values. Use measured, documented or assignment values rather than rounded estimates whenever possible.

Confirm every unit. The resistor color code calculator converts supported units before formula substitution, so each selector must describe the entered number.

Run the calculation. Review the displayed formula, normalized values and numeric substitution before accepting the final result.

Verify the answer. Reproduce the substitution manually and check whether the output is reasonable for the stated assumptions.

Resistor Color Code Calculator formula and unit checks

The resistor color code calculator keeps source inputs, canonical calculation units and displayed output units separate. This prevents a correct formula from producing a wrong answer because feet were treated as meters, percentages as decimals, or time values as the wrong interval.

For an independent check, copy the formula shown by the calculator, substitute the unrounded canonical values, preserve full precision through intermediate operations and round only the final result. The verified answer should match both the displayed number and its measurement unit.

How to interpret the resistor color code calculator result

A result is useful only when its assumptions match the real problem. Compare the answer with expected ranges, inspect any warning or boundary message, and test a nearby input to confirm that the output changes in the direction predicted by the governing relationship.

The resistor color code calculator provides an educational and planning result. For regulated, medical, structural, financial, laboratory or safety-critical decisions, verify the inputs and method against the applicable professional requirements before acting.

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Resistor Color Code Calculator quick verification checklist

Before saving or reporting a result from the resistor color code calculator, confirm the input source, unit selections, formula mode, intermediate substitution, final unit and rounding rule. These checks make the calculation reproducible and easier to audit.

Browse the complete published calculator sitemap or return to the Salar Cafe home page.

Resistor Color Code Calculator