Instantly convert Standard Wire Gauge (SWG) to millimetres, inches and cross-section area (mm²) — complete chart from 7/0 to 50 for wire drawing, sheet metal, roofing and electrical applications across India.
Select a gauge number to instantly see the diameter in mm, inches and cross-sectional area — or enter mm to find the nearest SWG.
Most Used Gauges in India — Click to Convert
Simple steps to convert Standard Wire Gauge in both directions instantly
Select SWG → mm to convert a known gauge number to millimetres. Select mm → SWG to find the nearest standard gauge for a measured or specified mm diameter. Both directions work instantly.
In SWG→mm mode, pick the gauge from the dropdown (7/0 to 50). In mm→SWG mode, type the diameter in mm. The converter finds the nearest SWG and shows the exact standard value for that gauge.
Results show diameter in mm, diameter in inches, and cross-sectional area in mm² — useful for wire current capacity calculations and material weight estimates.
The most commonly used gauges in Indian industry (SWG 8 to SWG 26) are listed as quick-click cards below the converter. Click any card to instantly populate all results without using the dropdown.
Use the search box above the full reference table below to filter by SWG number, mm value, or inch value. The matching row highlights in amber — useful when verifying measurements against a physical wire gauge tool on site.
Click any row in the full reference table to automatically populate the converter with that gauge. Convenient when comparing multiple sizes — click one row at a time to see all four result values update instantly.
How Standard Wire Gauge numbers relate to millimetre diameters and cross-section area
Unlike AWG (American Wire Gauge), SWG (Standard Wire Gauge) — also called Imperial Wire Gauge or British Standard Wire Gauge — has no single mathematical formula that generates all values. Each gauge diameter was defined by historical British Standard BS 3737:1964, which was adopted across India and Commonwealth countries. The values in this table are the official BS 3737 reference values.
This is the most confusing aspect for new users. SWG 8 = 4.064 mm (thick), SWG 26 = 0.457 mm (thin). The numbering convention originated from the number of drawing passes required to produce the wire from a rod — more passes = more reduction = higher gauge number. For roofing sheets in India, "26G" = SWG 26 = 0.457 mm and "24G" = SWG 24 = 0.559 mm.
Electrical engineers and electricians in India use SWG to specify wire sizes. The cross-section area (mm²) from this calculator directly relates to current-carrying capacity (CCC) per IS 732. For example, SWG 14 = 2.032mm = 3.243 mm² — this corresponds to approximately 3.5 mm² IS standard wire. Always use the IS 694 nearest standard cross-section for actual wiring specification.
In India, SWG is used for both wire diameters and sheet metal thickness — the same gauge number means the same physical dimension in both cases. A "SWG 18" GI sheet = 1.219 mm thick. A "18 SWG" GI wire = 1.219 mm diameter. The physical gauge tool (a flat disc with numbered slots) measures both wire and sheet using the same scale.
Complete Standard Wire Gauge reference table — click any row to populate the converter above
| SWG # | Diameter (mm) | Diameter (inches) | Area (mm²) | Common Use in India |
|---|
Showing all 57 gauges | Click any row to convert | Values per BS 3737:1964 / IS 280
SWG, AWG, BWG and IS — understanding which standard applies to your product
British origin (BS 3737). Used in India for GI wire, binding wire, roofing sheets (gauge designation), fencing wire, and electrical wiring. Most Indian hardware shops and steel stockists quote SWG. Governed by IS 280 (mild steel wire) and IS 12589 (GI wire).
US origin. Used in India for imported electrical cables, electronics components, PCB traces, and US-standard imported equipment. AWG and SWG values differ significantly — AWG 14 = 1.628mm whereas SWG 14 = 2.032mm. Never interchange without conversion.
Older British standard. Occasionally used in India for hypodermic needles, medical tubing, and some legacy steel tube specifications. Rarely seen in modern Indian construction or electrical applications. BWG values differ from SWG for the same gauge number.
Modern Indian Standards (BIS) increasingly specify wire and sheet thickness directly in millimetres rather than gauge numbers. IS 513 (CR sheets), IS 4923 (hollow sections), and IS 2062 (structural steel) all use mm. For new projects, mm specification is preferred — use this calculator to convert legacy SWG specs.
Industries and products that rely on Standard Wire Gauge specifications across India in 2026
Galvanized roofing sheets across India are commonly marketed in SWG. "26G" roofing sheets = SWG 26 = 0.457mm BMT. "24G" = SWG 24 = 0.559mm. Understanding SWG helps verify whether a supplier's "24G" sheet matches the IS 14246 specification thickness you've calculated for structural dead load.
Old-generation electricians and hardware stores across India still quote wire in SWG — "7/22 SWG" means 7 strands of 22 SWG wire. Modern IS 694 wiring specifications use mm² (1.5mm², 2.5mm², 4mm²) but SWG conversion remains essential for legacy panels, rewiring jobs, and imported equipment.
Chain link fencing, welded wire mesh, barbed wire, and GI hexagonal mesh sold at Indian hardware stockists are specified in SWG. Common fencing wire grades: SWG 8 (4.064mm), SWG 10 (3.251mm), SWG 12 (2.642mm), SWG 14 (2.032mm). Thicker SWG = more durable, heavier fencing.
Sheet metal workshops, HVAC duct fabricators, and enclosure manufacturers across India receive drawings specifying material in SWG. "16 SWG MS sheet" = 1.626mm mild steel. Fabricators need this conversion for cutting machine setup, bend radius calculation, and material procurement from steel service centres.
Needle gauges (hypodermic, IV cannulas) in Indian hospitals are specified in BWG/SWG. Pharmaceutical equipment — dosing tubes, filter screens, and stainless mesh — use SWG wire diameter as a process specification parameter for mesh opening calculation and flow rate estimation.
Wire drawing mills in Jamnagar, Ludhiana, Hyderabad, and Coimbatore produce mild steel and stainless steel wire to SWG specifications for downstream markets — nails, springs, binding wire, tyre bead wire, and welding wire. SWG defines the die sequence for the drawing process.
Practical guidance for engineers, fabricators, and procurement teams
SWG 14 = 2.032mm. AWG 14 = 1.628mm. That's a 20% difference in diameter and a 36% difference in cross-section area. In Indian electrical work, always confirm which gauge system is being used — especially with imported MCBs, cable glands, and terminal blocks that may reference AWG. When in doubt, measure with a micrometer and look up the result in this table.
When a roofing sheet supplier says "24G PPGI" they mean SWG 24 = 0.559mm — but this is the Base Metal Thickness (BMT) of the steel before zinc coating. The Total Coated Thickness (TCT) will be slightly more (~0.03–0.05mm). For structural dead load calculations, always use BMT from the MTC, not the SWG designation from the price list — they can differ if the supplier is quoting TCT as "gauge".
The standard SWG gauge tool (a circular steel disc with numbered slots) is available at every hardware shop in India for under ₹200. To measure: insert the wire or sheet edge into slots until it fits snugly without forcing. That slot number is your SWG. Then use this calculator to convert to mm. Avoid eyeballing — SWG 18 (1.219mm) and SWG 19 (1.016mm) look nearly identical without measurement.
To calculate the weight of SWG wire per metre: Weight (g/m) = Area (mm²) × Density (g/cm³) × 0.1. For mild steel (7.85 g/cm³), SWG 14 wire: 3.243 mm² × 7.85 × 0.1 = 2.55 g/m = 2.55 kg per 1000m coil. Use this to verify coil weight on delivery — standard GI wire coils sold in India are typically 25 kg or 50 kg and are often mislabelled at secondary markets.
Key Indian Standards that reference SWG: IS 280 (mild steel wire), IS 4826 (galvanized coatings on wire), IS 12589 (GI wire), IS 1199 (sampling of concrete), IS 14846 (wire for concrete reinforcement). When a BIS standard quotes "SWG XX", use this table to find the exact mm equivalent for your drawing, specification, or purchase order.
After calculating mm² from this converter, map to the nearest IS 694 conductor size for electrical wiring: 1.5 mm² (≈SWG 18), 2.5 mm² (≈SWG 16), 4 mm² (≈SWG 14), 6 mm² (≈SWG 12), 10 mm² (≈SWG 10). IS 732 Table 4 gives the permitted current for each standard cross-section. Always size by mm² in your electrical drawings — SWG is only used for ordering from hardware suppliers.
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Common SWG to mm conversion questions answered for Indian engineers, electricians and fabricators