RES
Value = original code formula: value = digits × 10multiplier, formatted in µH / mH.
Input Parameters Specification
First / Second DigitsSignificant figure digits printed on the axial molded choke body casing representing the nominal base inductance value.
Third Band (Military Silver)Utilized in specialized 5-band military spec chokes. The wide silver band defines standard military testing qualifications.
Decimal MultiplierScales base digits exponentially in microhenries (µH) or millihenries (mH) to represent different structural ranges.
Tolerance RatingDetails percentage manufacturing variances allowed under thermal swings and standard high-frequency loads.
Practical Operational Examples
10µH Molded Choke
Typically 4-band: Brown (1), Black (0), Black (x1), Silver (±10%). Popularly chosen for basic power supply filtering.
1.5µH High-Spec Inductor
Standard 5-band: Silver (Military), Brown (1), Green (5), Gold (x0.1), Gold (±5%). Found in high-frequency RF impedance matching.
EMI Noise Cancellation
Decouples high-frequency spikes on power branches. Selected based on maximum target line currents.
Standard Logarithmic Step
Aligns within E12 or E24 standard industrial grids, simplifying component catalog sourcing.
Diagrams & Theory
Axial mold inductors use standard color bands to communicate critical parameters. The visual model above shifts colors dynamically in real time and features a green body, distinguishing it clearly from resistors on visual inspection.
These codes follow international standards, allowing technicians and automated scanning systems to identify inductor parameters in active circuits.
Formulas & Mathematical Logic
For 3 & 4-Band: Value = (Digit 1 × 10 + Digit 2) × Multiplier (µH)
For 5-Band: Value = (Digit 2 × 10 + Digit 3) × Multiplier (µH) [First Wide Band is Silver]
Minimum tolerance limit: Lmin = Value - (Value × Tolerance / 100)
Maximum tolerance limit: Lmax = Value + (Value × Tolerance / 100)
Step-by-Step Example
Example: 4-Band Inductor - Yellow (4), Violet (7), Black (x1), Gold (±5%)
Step 1: Write down the primary digits: Digit 1 = 4, Digit 2 = 7. Combine them to get: 47.
Step 2: Multiply the combined digits by the multiplier band value: 47 × 1 = 47 µH.
Step 3: Factor in the tolerance to find the operational range: 47 µH ± 5% gives an acceptable window of 44.65 µH to 49.35 µH.
How to Use This Calculator
Choose the band count (3, 4, or 5 bands) to match your physical component.
Inspect the axial inductor and locate the band closest to the lead wire. Read left to right.
Select the band colors using the selection picker menus.
The calculated values, tolerances, and multiplier are updated instantly.
About This Calculator
Decode axial molded inductors with speed.
This tool helps you quickly read inductance values, multipliers, and tolerance ratings for standard axial components.
Color bands are used on axial inductors because printed text on small, curved surfaces can easily smudge or fade, or be covered when soldered in place.
Using standard inductor values simplifies design and component sourcing. Sticking to standard logarithmic scales (like E12 or E24) ensures components are easy to find and cost-effective to manufacture.
Ideal ForBreadboarding, filter debugging, and RF choke calculations.
Decodes BandsDecodes 3, 4, and 5 axial bands.
Precision CheckIdentifies maximum and minimum bounds to assist with circuit testing.
Military SpecsSupports 5-band chokes starting with a wide silver band.
Tip: Always measure the inductor with a multimeter if you are unsure of its value or if the bands are faded.
Frequently Asked Questions
1. How do I read an axial mold inductor color code?
Locate the band closest to one of the metal leads. Read the bands in order from that side to find the digits, multiplier, and tolerance.
2. Why do some 5-band inductors start with a wide silver band?
A wide silver band on a 5-band inductor indicates a military-standard specification component, representing an established quality standard.
3. What is the standard unit of measurement for color-coded inductors?
Color-coded axial inductors are measured in microhenries (µH) as their base unit of calculation.
4. What does the tolerance rating on an inductor mean?
The tolerance rating represents the expected manufacturing variations in inductance, expressed as a plus or minus percentage of its nominal value.
5. How do axial inductors differ from axial resistors visually?
Though identical in physical structure, inductors are molded with a dark-green or olive body, whereas resistors typically have a beige, blue, or light gray body.
6. Can I install an axial inductor in any direction?
Yes. Inductors are non-polarized components and can be connected safely in either direction in a circuit.
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