Product Tolerance Guide

Inductance Tolerance

Parts are manufactured to the published AL values; permeability listed for each material is for reference only. All standard parts are manufactured to tolwerances as follows:

Iron Powder Cores 

  • RF material   +/-5%
  • Power conversion   +/-10%

 Alloy Powder Cores

  • +/-8% most Alloy Cores
  • MS (Sendust) Toroids with OD's between 0.25in. to 0.44 in. have ±12% inductance tolerance
  • MS (Sendust) Toroids with OD's less than OD 0.25in. have ±15% inductance tolerance

Toroidal cores are tested with an evenly-spaced full single-layer winding in order to minimize leakage effects. Powder cores tested with a small number of turns or turns that are not evenly spaced around the core will produce higher inductance readings than expected.

Refer to individual part datasheets for full dimensional tolerance, inductance tolerance, test winding and testing conditions. Magnetic curve graphs and equations listed on this website, published catalogs and datasheets have typical tolerance of +20%/-10%. Core loss characteristic curves and equations have typical tolerance of ±15%.



Inductance Rating

AL values are expressed in nanohenries (10-9 Henries) per turn (N) squared (nH/N2).
To calculate the number of turns required for a desired inductance (L) in nanohenries (nH) use the following formula:


Inductance Grading

Binning and marking in 1% grades is possible upon request.