Calculating interwinding capacitance of inductor

[ocset]

We wish to use Power inductors for filtering SMPS. We want them to have as little  interwinding capacitance as possible because we want to  maximally impede the  high frequency common mode noise from getting through this stray capacitance.
As you know, interwinding capacitance is not listed in inductor datasheets, so please could you confirm that the “Self Resonant Frequency” is what we need to use to calculate this stray capacitance?
Thats is,   w = 1/[(sqrt(LC)]
Therefore  C = 1/(w^2 * L)

[PChi]

It looks OK to me but it is treating the interwinding capacitance as one element rather than distributed with the inductance so it's not an exact model.

[HighVoltage]

Your formula should work correctly.
Make also some measurements at below and above resonance and see that you get the same value for C. I always also use my LCR meter and force it in to C-Measurement. If your stray capacitance is of good value, depending on your LCR meter and measurement frequency, you can get a good and stable reading.
 

[T3sl4co1l]

This is a modeling problem:

The "capacitance" is not a true capacitor, but a distributed (transmission line) effect.

We can construct a model which approximates it, but which is not physically representative.

To that end, the most accurate models I know of are by Coilcraft.  This page gives an explanation of their model design, a viewer, and a way to rewrite their models for use in all SPICE simulations.
https://www.seventransistorlabs.com/Calc/Coilcraft1.html
Coilcraft's SPICE page is linked, where you will find parameters for most of their parts.  If you are looking at another brand, it may be close enough to look for a Coilcraft cross-reference.

Downside: most of the models stop abruptly after (and sometimes before) the self resonant frequency.  Therefore, we should suppose that these models are not very accurate above the SRF, and the capacitance given is only a fit for that range, not a physical value.

In practice, there will be numerous dips and peaks (series and parallel resonances) above the first SRF, depending on the exact placement and number of turns in the part.  These features cannot be represented with the above model.

Tim