SWG
Please select a valid SWG gauge.
RESULTS
Input Parameters Specification
GaugeSelect the Standard Wire Gauge value from 7/0 to 50 for wire diameter conversion.
Diameter in InchShows the matching SWG wire diameter in inches from the lookup table.
Diameter in MMConverts the selected SWG diameter from inches to millimeters.
Area in MM²Calculates circular wire cross-sectional area using the converted millimeter diameter.
Practical Operational Examples
Electrical Wire Selection
Convert SWG to mm before selecting cable size for coils, transformer winding, and electrical wiring.
Workshop Gauge Check
Use the SWG to millimeter converter to compare wire gauge, diameter, and cross-sectional area quickly.
Diagrams & Theory
SWG is a wire gauge standard where each gauge number maps to a fixed wire diameter. The converter uses diameter lookup data and then calculates area from the round wire diameter.
Formulas & Mathematical Logic
Step 1: Select SWG gauge from the dropdown list.
Step 2: The calculator reads the matching diameter in inches from the original SWG lookup table.
Step 3: Diameter in mm = Diameter in inch × 25.4.
Step 4: Cross-sectional area in mm² = (π / 4) × diameter².
Step-by-Step Example
Example: Select 20 SWG from the gauge dropdown.
The calculator reads the matching SWG diameter from the built-in lookup table.
It converts inch diameter to millimeters using d mm = d inch × 25.4.
Then it calculates round wire area using Area = π / 4 × d².
The output shows diameter in inches, diameter in mm, and cross-sectional area in mm².
How to Use This Calculator
Open the Gauge dropdown.
Select the required SWG value from 7/0 to 50.
Click Calculate.
Read the wire diameter in inches and millimeters.
Use the mm² area output for coil, cable, and conductor comparison work.
About This Calculator
Convert Standard Wire Gauge into practical wire dimensions.
The CalcBoy SWG to MM Converter helps convert SWG gauge values into inch diameter, millimeter diameter, and circular wire area in mm².
Standard Wire Gauge is still used in many workshops, electrical repair jobs, coil winding charts, heating element references, and older engineering documents. The problem is that many modern cable datasheets and conductor calculations use millimeters or square millimeters instead of SWG. This converter bridges that gap by giving the direct wire diameter and cross-sectional area from a selected SWG size.
The diameter value is useful when measuring wire with a caliper, replacing old winding wire, comparing workshop stock, or matching a wire size listed in an older manual. The mm² area is helpful when comparing current-carrying ability, resistance, and conductor size. This tool is not a replacement for full electrical cable selection rules, but it is very useful when you need quick SWG to millimeter conversion before doing further electrical or mechanical checks.
Best UseSWG wire diameter conversion for workshop, coil, repair, and electrical reference work.
Output UnitsInches, millimeters, and cross-sectional area in mm².
Practical TipUse a caliper to confirm real wire diameter, especially for old or coated wire.
Design ReminderInsulation thickness is not included; this converter is for conductor diameter only.
Tip: Magnet wire and enamelled copper wire may measure slightly larger with coating. For winding calculations, check whether your reference chart needs bare conductor diameter or finished outside diameter.
Frequently Asked Questions
What is SWG?
SWG means Standard Wire Gauge, a wire sizing system where each gauge corresponds to a fixed wire diameter.
Does higher SWG mean thinner wire?
Yes. In general, larger SWG numbers represent thinner wire diameters.
How is SWG converted to mm?
The calculator reads the SWG diameter in inches from the lookup table, then multiplies by 25.4 to convert it into millimeters.
How is wire area calculated?
Wire area is calculated as Area = π / 4 × diameter² using the diameter in millimeters.
Can I use this for enamelled copper wire?
Yes, but remember that enamel coating may increase the measured outside diameter compared with bare conductor diameter.
Is SWG the same as AWG?
No. SWG and AWG are different wire gauge systems, so the same number does not always mean the same wire diameter.
Can this be used for cable current rating?
It can help compare conductor size, but final current rating depends on material, insulation, temperature, installation method, and local electrical rules.
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