Advanced Litz Magnet Wire Calculator

1. Electrical & Operating

Operating Frequency (kHz)

Example: 100 kHz for high-frequency switch-mode supplies.

RMS Current ($I_{rms}$ in A)

Example: 15.0 Amps RMS through the winding.

Estimated Wire Length (m)

Example: 2.5 meters total winding length.

2. Strand & Geometry

Single Strand Gauge (AWG)

Select individual strand thickness.

Number of Strands ($N$)

Example: 600 individual insulated strands.

Packing Factor ($k_p$)

Typical litz bundle packing factor (0.5 - 0.65).

3. Thermal Parameters

Ambient Temperature (°C)

Example: 40 °C operational environment.

Max Allowed Temp Rise (°C)

Example: 30 °C temperature increase limit.

Formulas Used in Litz Wire Calculations

Designing high-frequency magnetic components requires accounting for skin and proximity phenomena. The key relationships applied within this script include:

Skin Depth ($\delta$): $\delta = \sqrt{\frac{\rho}{\pi \cdot f \cdot \mu_0 \cdot \mu_r}}$ where $\rho$ is copper resistivity, $f$ is frequency, and $\mu$ is permeability.
Total Copper Area ($A_{cu}$): $A_{cu} = N \cdot \pi \cdot r^2$ where $N$ is total number of isolated strands and $r$ is individual strand radius.
AC Resistance Estimation: $R_{ac} = R_{dc} \cdot \left[1 + \frac{(r / \delta)^4}{48} \cdot \sqrt{N}\right]$ based on Dowell's simplified high-frequency loss approximations.
Conductor Power Loss ($P_{loss}$): $P_{loss} = I_{rms}^2 \cdot R_{ac}$ representing total ohmic thermal dissipation.

How to Use This Calculator

Input your target operating frequency in kilohertz (kHz) and RMS current.
Select the correct individual strand American Wire Gauge (AWG) size and input total strand count.
Specify ambient environmental temperatures and thermal rise thresholds.
Click the Calculate Performance button to review immediate skin depth, resistance ratios, and overall thermal results above the form.

Advanced Engineering Guide to Litz Magnet Wire in Power Electronics

Litz wire is a specialized type of stranded wire used in electronics to mitigate skin effect and proximity effect losses in conductors operating at high frequencies. As frequency increases, alternating current tends to flow only along the outer periphery of a solid conductor, drastically shrinking the effective conductive area and escalating resistance. By utilizing numerous thinly isolated wire strands twisted or braided together uniformly, litz wire forces current sharing across all strands, reducing excessive AC resistance and preventing destructive thermal hotspots.

Mitigating High-Frequency Parasitic Losses

In high-power resonant converters, wireless power transfer systems, and switch-mode transformer designs, minimizing winding losses is critical for overall efficiency and thermal compliance. Standard solid copper wire experiences exponential resistance amplification past tens of kilohertz due to eddy currents generated by neighboring magnetic fields. Selecting an appropriate litz bundle configuration requires balancing strand gauge against operational skin depth. Individual strands must be chosen so their diameter is smaller than twice the skin depth calculated at your peak harmonic frequencies.

Frequently Asked Questions

Each individual strand must remain smaller than twice the skin depth parameter at the target frequency to ensure complete current penetration and avoid severe skin effect losses.

Packing factor represents the ratio of actual copper cross-section to total occupied bobbin space. Because of insulation layers and air gaps between twisted strands, litz wire has a lower packing factor than solid wire, requiring careful bobbin window design.