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Resistor Calculator

Use this resistor calculator to convert compatible units or encoded values for resistor.

Primary answer
Resistance
Inputs to verify
Band count, First digit band, and Second digit band
Use type
Use as a direct calculation check.
Keyword intent
resistor calculator

Calculator

Resistor Calculator

Calculates resistance from band count, first digit band, second digit band. Defaults are filled in so you can review a working example before changing inputs.

Choose 4-band or 5-band fixed resistor color code.

First significant digit color. Black is rejected as the first digit in this MVP.

Second significant digit color.

Third significant digit color, used only for 5-band resistors.

Multiplier color applied to the significant digits.

Tolerance band color. None means +/-20%.

Result

Result reflects the current submitted inputs.

  • Risk A
  • Reviewed 2026-05-26
  • 2 sources
Resistance4,700 ohm
Tolerance5%
Minimum resistance4,465 ohm
Maximum resistance4,935 ohm
Significant value47
Multiplier100
Band codeyellow violet red gold
  • 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.

Categories

What the result means

Resistance is the number to carry forward from this resistor calculation. Nominal resistance in ohms. Read the converted value first, then verify the source unit, target unit, and factor before reusing the number. Use tolerance, minimum resistance, and maximum resistance to explain why resistance moved when an input changed. Keep the original value next to the converted value when using it in a workflow. Check source unit, target unit, dimension compatibility, exchange or conversion rate, and rounding precision before treating the result as final.

ResistanceNominal resistance in ohms.
ToleranceSymmetric tolerance percentage from the tolerance band.
Minimum resistanceResistance at nominal minus tolerance.
Maximum resistanceResistance at nominal plus tolerance.

Use the result this way

  1. Start with Resistance, then use supporting outputs only to explain the primary answer.
  2. Verify band count, first digit band, and second digit band before copying the result.
  3. Choose the mode or method first because it can change which formula is applied.
  4. Keep the original value next to the converted value when using it in a workflow.

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 2026-05-26.

Next useful step

  • Ohm's Law CalculatorUse next when the engineering task needs voltage instead of resistance.
  • Bandwidth CalculatorUse next when the engineering task needs transfer time instead of resistance.
  • BTU CalculatorUse next when the engineering task needs estimated cooling capacity instead of resistance.

Formula

For 4 bands, resistance = (10 x first digit + second digit) x multiplier. For 5 bands, resistance = (100 x first digit + 10 x second digit + third digit) x multiplier. Key assumptions: 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.

  • For 4 bands, resistance = (10 x first digit + second digit) x multiplier. For 5 bands, resistance = (100 x first digit + 10 x second digit + third digit) x multiplier.
  • 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.
  • Primary source context: International Electrotechnical Commission.

Inputs

Enter band count, first digit band, second digit band, and third digit band for unit checks, engineering notes, recipes, travel, and measurement cleanup. Before calculating, choose the mode or method first because it can change which formula is applied. Band count: Choose 4-band or 5-band fixed resistor color code. First digit band: First significant digit color. Black is rejected as the first digit in this MVP. Second digit band: Second significant digit color. Third digit band: Third significant digit color, used only for 5-band resistors.

Band countChoose 4-band or 5-band fixed resistor color code.
First digit bandFirst significant digit color. Black is rejected as the first digit in this MVP.
Second digit bandSecond significant digit color.
Third digit bandThird significant digit color, used only for 5-band resistors.
Multiplier bandMultiplier color applied to the significant digits.
Tolerance bandTolerance band color. None means +/-20%.

Example

Using the default inputs, Resistor Calculator returns resistance of 4,700 ohm. Adjust band count, first digit band, second digit band, and third digit band to match your own scenario.

FAQ

How is resistance calculated here?

For 4 bands, resistance = (10 x first digit + second digit) x multiplier. For 5 bands, resistance = (100 x first digit + 10 x second digit + third digit) x multiplier. The first assumption to check is: This MVP decodes common 4-band and 5-band fixed resistor color codes only.

What does Resistance mean for resistor?

Read the converted value first, then verify the source unit, target unit, and factor before reusing the number. Secondary values such as tolerance, minimum resistance, and maximum resistance are there to explain the primary answer, not to replace it.

What should I enter for Band count?

Choose 4-band or 5-band fixed resistor color code. Choose the mode or method first because it can change which formula is applied.

How does First digit band change resistance?

First significant digit color. Black is rejected as the first digit in this MVP. Changing it can alter resistance because the formula uses the submitted inputs together. Also compare source unit, target unit, dimension compatibility, exchange or conversion rate, and rounding precision.

Why does the resistor example show 4,700 ohm for resistance?

The default inputs produce 4,700 ohm for resistance. Treat that as a format and scale check, then replace every default value with your own inputs.

How do I avoid a resistor unit-direction mistake?

Keep the original value beside the converted value, confirm both units measure the same quantity, and check whether rounding is acceptable for the task.

Sources

Last reviewed: 2026-05-26

  • Reviewed 2026-05-26
    IEC 60062:2016 - Marking codes for resistors and capacitorsInternational Electrotechnical Commission. Authority for resistor color-code marking, resistance value coding, tolerance coding, and multiplier color concepts used by this MVP.
    Scope
    Designation and marking codes for capacitors and resistors, including colour coding for resistors.
    Supports
    Authority for resistor color-code marking, resistance value coding, tolerance coding, and multiplier color concepts used by this MVP.
  • Reviewed 2026-05-26
    SI Units - Electric CurrentNational Institute of Standards and Technology. Ohm as the SI unit of electrical resistance and 1 ohm = 1 V/A.
    Scope
    SI electric current page covering volt and ohm relationships.
    Supports
    Ohm as the SI unit of electrical resistance and 1 ohm = 1 V/A.