Inductor Series Resistance Calculator

Model winding resistance across temperature and conductor choices. Review losses, Q factor, and heating estimates. Use practical inputs for prototyping troubleshooting validation and documentation.

Calculator Form

Example Data Table

Material Wire Length (m) Wire Diameter (mm) Inductance (µH) Frequency (kHz) Q Temp (°C) Geometry ESR (Ω) Q Method ESR (Ω)
Copper 2.6 0.85 47 10 35 40 0.085201 0.084374
Aluminum 3.4 0.80 68 20 45 35 0.201318 0.189892
Silver 5.0 0.70 100 25 40 30 0.209155 0.392699

Formula Used

1. Conductor cross sectional area: A = πd²/4 × strands

2. Reference winding resistance: Rref = ρL / A

3. Temperature corrected resistance: Rtemp = Rref × [1 + α(T − Tref)]

4. Inductive reactance: XL = 2πfL

5. Series resistance from Q: ESR = XL / Q

6. Skin depth estimate: δ = √[ρ / (πfμ0)]

7. Simple AC factor estimate: AC Factor = max(1, radius / 2δ)

8. Estimated AC series resistance: Rac ≈ Rtemp × AC Factor

9. Copper loss: P = I²R

10. Voltage drop: Vdrop = I × R

This page compares a geometry based estimate with a Q based estimate. The skin effect model is simplified. Use measured data for final validation.

How to Use This Calculator

  1. Select the conductor material. Choose custom if you want to enter your own resistivity and temperature coefficient.
  2. Enter wire length, wire diameter, and strand count to estimate winding resistance from conductor geometry.
  3. Enter inductance and operating frequency to calculate reactance.
  4. Enter Q factor when you want a series resistance estimate from measured or datasheet quality factor.
  5. Enter operating current if you want voltage drop and copper loss values.
  6. Press calculate. The results appear above the form and below the header section.
  7. Use the CSV button for spreadsheet work. Use the PDF button for reports or sharing.

Inductor Series Resistance in Real Engineering Work

Why series resistance matters

Inductor series resistance affects efficiency, heat, and voltage drop. It is often called DCR when measured at low frequency. At higher frequency, the effective resistance can rise. That happens because current crowds near the conductor surface. A practical calculator helps engineers compare these effects quickly.

Geometry based estimation

The first method uses conductor geometry. It starts with resistivity, wire length, and conductor area. That gives a baseline winding resistance. The calculator then adjusts the result for operating temperature. This matters because copper and aluminum resistance increase with heat. A hotter winding usually means more loss and lower overall performance.

Q factor based estimation

The second method uses inductance, frequency, and Q factor. This is useful when you have a datasheet or measured Q value. The relationship is simple. Series resistance equals inductive reactance divided by Q. This method often reflects real operating behavior better than a basic DC estimate. It is especially useful in tuned circuits and filter work.

How to interpret the output

Use the geometry result for winding design, conductor selection, and temperature studies. Use the Q based result for validation against measured performance. If both values are close, your design assumptions may be reasonable. If they differ a lot, look at proximity effect, core loss interaction, lead resistance, and measurement conditions.

Where this calculator helps

This inductor series resistance calculator supports power electronics, RF prototypes, and general engineering checks. It helps estimate copper loss, compare materials, and review expected voltage drop under load. It also supports documentation because the page includes export options, formulas, and an example table. That makes it useful for design reviews, maintenance notes, and lab reporting.

FAQs

1. What is inductor series resistance?

It is the resistive part in series with the ideal inductance. It comes from winding resistance, leads, joints, and frequency related conductor effects. Higher values increase loss and heat.

2. Is series resistance the same as DCR?

DCR is the low frequency winding resistance. Series resistance at operating frequency can be higher because skin effect and proximity effect increase the effective conductor resistance.

3. Why does temperature change the result?

Metal resistance rises with temperature. A warmer inductor winding usually has higher resistance, which increases copper loss and changes performance under load.

4. When should I use the Q method?

Use it when you know inductance, frequency, and Q factor from a datasheet or measurement. It is often better for real operating behavior than a simple DC estimate.

5. Why are geometry and Q results different?

The geometry method estimates conductor loss from physical dimensions. The Q method reflects measured behavior. Differences can come from skin effect, proximity effect, test setup, and lead resistance.

6. Does this calculator include core loss?

No. This page estimates series resistance related outputs. Core loss is separate and depends on core material, flux density, waveform, and frequency.

7. Can I use aluminum or silver wire?

Yes. The calculator includes preset materials and a custom option. That lets you compare resistivity and temperature coefficient effects during early design work.

8. Is the AC factor exact?

No. It is a simple estimate for quick engineering checks. Final work should use measured impedance, detailed field models, or vendor data when accuracy is critical.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.