Complete Guide to Inductor Number Codes
Inductor number codes help makers read small parts without long labels. The code usually gives an inductance value in microhenries. A three digit code uses two significant digits and one multiplier digit. A four digit code uses three significant digits and one multiplier digit. Decimal values often use the letter R. For example, 4R7 means 4.7 microhenries.
Why This Calculator Helps
Manual decoding is easy for one part. It becomes slow when many parts are checked. This calculator accepts standard number codes, decimal R markings, and tolerance letters. It then converts the answer into henries, millihenries, microhenries, and nanohenries. These unit conversions reduce mistakes during design, repair, testing, and purchasing work.
Understanding Tolerance
Tolerance tells how far the real part may vary. A 100 microhenry inductor with ten percent tolerance can measure from 90 to 110 microhenries. This range matters in filters, timing circuits, power supplies, and radio circuits. Tight tolerance parts are useful when a circuit needs predictable frequency or current behavior.
Encoding Values
The calculator also helps create a code from a known inductance value. Enter the value, choose the unit, and select two or three significant digits. The tool suggests a practical marking. Values below ten microhenries may be easier to show with R notation. Larger values usually fit standard multiplier notation.
Choosing Units
Use nanohenries for tiny radio coils. Use millihenries for chokes and filters. Use henries for large coils. Keeping one base unit makes comparisons safer during quick bench reviews.
Good Practice
Always confirm the marking style used by the component maker. Some older parts, molded inductors, or regional parts may follow special systems. Use measured inductance when accuracy is critical. A handheld LCR meter gives better proof than a printed code alone. Temperature, frequency, and core material can also change behavior.
Using Results
The result table is designed for records. You can export the result as a CSV file for spreadsheets. You can also create a PDF report for job notes, lab records, or client files. The example table shows common markings. Compare your component with these examples before applying the value in a real circuit. The calculator gives fast guidance, but final circuit validation is still important.