ROUND WIRE · FLAT WIRE · LITZ WIRE
Magnet Wire Resistance & Weight Calculator
Calculate DC resistance, bare-copper weight and copper loss from your wire size and length. You can also find the winding length needed for a target DCR at 20 °C, including both leads.
Calculate wire resistance, copper weight and DC loss
Live resultsMETHOD & ASSUMPTIONS
How wire resistance and copper weight are calculated
Calculation method
Electrical resistance and copper weight use bare copper dimensions. Insulation, adhesive, serving and empty space are excluded from copper area.
For a rectangular conductor with rounded corners, A = w × t − (4 − π) × r². For Litz wire, total copper area is the sum of the individual strand areas. Enter a lay-length factor when the copper path is longer than the bundle path.
Copper resistivity at 20 °C: 0.017241 Ω·mm²/m. Temperature coefficient: 0.00393 /°C. Copper density: 8.96 g/cm³.
Scope of this estimate
AWG refers to nominal bare round conductor diameter. It does not specify the enamelled or served outside diameter.
This is a DC conductor estimate. Litz strands are assumed to be identical, connected in parallel at both ends and equally terminated. AC resistance, proximity effect, temperature rise and safe current ratings are outside this model.
The selected temperature is the copper temperature supplied by you. Lead length is added once: two leads of the entered length, with the same conductor cross-section as the winding.
WORKED EXAMPLE · NOT A PRODUCT SPECIFICATION
Example: 0.5 mm round copper wire
For 10 m of 0.5 mm bare round copper wire plus two 60 mm leads, the total copper length is 10.12 m. The calculated resistance is about 0.8886 Ω at 20 °C and the bare-copper weight is about 17.80 g. At a fixed DC current of 1 A, copper loss is about 0.8886 W. Enamel, adhesive and solder are excluded.
BEFORE YOU SPECIFY
Common design questions
Is AWG the finished wire diameter?
No. AWG gives nominal bare conductor diameter. Obtain the actual insulated outside diameter from the wire supplier before calculating winding fit.
Does the copper weight include two leads?
Yes. Each lead is 60 mm by default and can be edited. The result includes bare copper only, excluding enamel, serving, glue and solder.
Can I use this result as an AC resistance or current rating?
No. DC copper loss uses the entered current and DC resistance. High-frequency loss, thermal performance and allowable operating current need further material, winding and assembly data.
At what temperature is the target resistance specified?
The resistance-to-length mode uses total DC resistance at 20 °C, including both leads. The calculator then estimates resistance and DC copper loss at the copper temperature you enter. That temperature is an input, not a predicted temperature rise.
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