Complete automotive sheet metal gauge guide for fabricators, restorers and body shop technicians. Body panel thickness chart, interactive gauge finder, steel vs aluminium comparison, AHSS guide, repair & restoration tips — updated 2026.
Essential gauge numbers every fabricator, restorer and body shop technician should know
Find the gauge from a measured thickness, or look up mm and inches for a known gauge number — for both steel and aluminium
Automotive steel uses the Manufacturer's Standard Gauge (MSG). Aluminium uses the Brown & Sharpe (B&S) gauge. The gauge finder above is for steel only. Always confirm the material before ordering — use a magnet test (steel is magnetic, aluminium is not). Ordering aluminium by steel gauge numbers is a common and costly mistake.
Recommended steel gauge by vehicle panel or structural zone — based on 2026 OEM specifications and industry fabrication practice
Standard Manufacturer's Standard Gauge (MSG) reference for automotive mild steel and galvanized steel — with kg/m² and automotive applications
| Gauge | Inches | mm | kg/m² | Automotive Application | Zone |
|---|---|---|---|---|---|
| 8 | 0.1644 | 4.175 | 32.77 | Heavy structural, skid plates, frame sections | Structural |
| 10 | 0.1345 | 3.416 | 26.82 | Frame rails, chassis sections, ladder frames | Structural |
| 11 | 0.1196 | 3.038 | 23.85 | Subframe repairs, heavy mounting brackets | Structural |
| 12 | 0.1046 | 2.656 | 20.85 | Floor reinforcement, engine mount plates | Structural |
| 13 | 0.0897 | 2.278 | 17.88 | Structural inner panels, crossmembers | Structural |
| 14 | 0.0747 | 1.897 | 14.89 | Firewall, floor pans (heavy-duty), bulkhead | Structural |
| 16 | 0.0598 | 1.518 | 11.92 | Floor pans, truck beds, rocker reinforcement | Body |
| 18 | 0.0478 | 1.214 | 9.53 | Classic body panels, patch panels, floor sections | Most Common |
| 19 | 0.0418 | 1.062 | 8.34 | Inner door skins, wheel arch liners, inner sills | Body |
| 20 | 0.0359 | 0.911 | 7.15 | Modern body panels, hoods, trunk lids, roof | Body |
| 22 | 0.0299 | 0.759 | 5.96 | AHSS door skins, lightweight roof, inner braces | Body |
| 24 | 0.0239 | 0.607 | 4.76 | Inner door reinforcement, close-out panels | Thin |
| 26 | 0.0179 | 0.455 | 3.57 | Exhaust heat shields, underbody aero covers | Thin |
| 28 | 0.0149 | 0.379 | 2.97 | Heat shield foil, interior trim backing | Thin |
* Manufacturer's Standard Gauge (MSG) for carbon/mild steel. Density = 7.85 g/cm³. Reference: Metal Supermarkets Gauge Chart and CustomPartNet Gauge Standard. Weight calculated as: kg/m² = thickness (mm) × 7.85.
Brown & Sharpe (B&S) gauge reference for automotive aluminium — used in hoods, doors, EV bodies and premium vehicles
| Gauge | Inches | mm | kg/m² | Automotive Application | Zone |
|---|---|---|---|---|---|
| 8 | 0.1285 | 3.264 | 8.81 | Heavy structural brackets, skid plates | Structural |
| 10 | 0.1019 | 2.588 | 6.99 | Chassis sections, heavy floor structures | Structural |
| 12 | 0.0808 | 2.052 | 5.54 | Structural inner panels, bulkheads | Structural |
| 14 | 0.0641 | 1.628 | 4.40 | Floor pans, firewall (aluminium-intensive build) | Body |
| 16 | 0.0508 | 1.290 | 3.48 | Truck beds, cargo panels, F-150 cab inner | Body |
| 18 | 0.0403 | 1.024 | 2.76 | Outer panels (trucks, SUVs), bonnet / hood | Common |
| 20 | 0.0320 | 0.813 | 2.20 | Lightweight body panels, doors (EV / sports) | Body |
| 22 | 0.0253 | 0.643 | 1.74 | Lightweight hoods, deck lids, roof panels | Body |
| 24 | 0.0201 | 0.511 | 1.38 | Interior trim panels, inner door facings | Thin |
| 26 | 0.0159 | 0.404 | 1.09 | Heat shields, splash guards, underbody covers | Thin |
* Brown & Sharpe (B&S) gauge system for aluminium. Density = 2.70 g/cm³. Same gauge number gives different physical thickness than steel — see comparison table below. Reference: SheetGauge Aluminium Weight Calculator.
Critical side-by-side comparison — the same gauge number means a different physical thickness depending on material. Essential knowledge before ordering repair metal.
| Gauge | Steel (MSG) mm | Aluminium (B&S) mm | Thickness Diff. | Al % Thinner | Weight Saving (Al) | Typical Automotive Zone |
|---|---|---|---|---|---|---|
| 10 | 3.416 | 2.588 | 0.828 mm | −24% | ~66% lighter | Chassis / heavy structural |
| 12 | 2.656 | 2.052 | 0.604 mm | −23% | ~65% lighter | Floor reinforcement |
| 14 | 1.897 | 1.628 | 0.269 mm | −14% | ~67% lighter | Firewall, floor pan |
| 16 | 1.518 | 1.290 | 0.228 mm | −15% | ~66% lighter | Floor pans, truck beds |
| 18 | 1.214 | 1.024 | 0.190 mm | −16% | ~67% lighter | Body panels, hood, doors |
| 20 | 0.911 | 0.813 | 0.098 mm | −11% | ~66% lighter | Modern body panels |
| 22 | 0.759 | 0.643 | 0.116 mm | −15% | ~67% lighter | AHSS / lightweight roof |
| 24 | 0.607 | 0.511 | 0.096 mm | −16% | ~66% lighter | Inner reinforcement / covers |
* Weight saving (aluminium vs steel) is approximately constant at ~66% because the density ratio (2.70 vs 7.85 g/cm³) dominates over the thickness difference. For exact weight calculation, use the Aluminium Sheet Weight Calculator or MS Sheet Weight Calculator.
How AHSS changes gauge selection in 2026 OEM vehicles — and what repair shops and restorers need to know
| AHSS Grade | Typical Gauge | Thickness (mm) | Yield Strength | OEM Application (2026) | Mild Steel Equivalent |
|---|---|---|---|---|---|
| DP 590 | 20–22 | 0.76–0.91 | 590 MPa | Door outer skins, roof panels | 18 gauge mild steel |
| DP 780 | 20–22 | 0.76–0.91 | 780 MPa | B-pillar, side sill reinforcement | 16–18 gauge mild steel |
| DP 980 | 20–22 | 0.76–0.91 | 980 MPa | Ford Explorer doors, GM Ultium battery surrounds | 14–16 gauge mild steel |
| Martensitic 1200 | 22–24 | 0.61–0.76 | 1200 MPa | Door intrusion beams, bumper reinforcement | 12–14 gauge mild steel |
| Hot-Stamped Boron | 22 | 0.76–1.0 | 1500+ MPa | A-pillar, B-pillar, rocker (Audi A8, BMW 3-Series) | 10–12 gauge mild steel |
| TWIP Steel | 20 | 0.91–1.0 | 600–900 MPa | Volvo XC90 doors (1.0 mm vs prior 1.4 mm HSLA) | 16–18 gauge mild steel |
| Complex Phase (CP) | 20 | 0.9 | 780–1000 MPa | GM Ultium EV battery tray (0.9 mm) | 16 gauge mild steel |
⚠ AHSS panels cannot be substituted with equivalent gauge mild steel in structural repairs without OEM approval. Incorrect gauge or grade in crumple zones and pillars can invalidate crash safety performance. Always reference the vehicle manufacturer's body repair manual. Reference: Anebon Automotive Gauge Guide and Motor World Report 2025.
Actual gauge specifications from production vehicles — useful reference for restoration, repair and fabrication work in 2026
| Vehicle / Year | Panel | Gauge | Thickness | Material | Notes |
|---|---|---|---|---|---|
| 1965 Ford Mustang | Quarter panels, doors | 18 | 1.214 mm | Cold-rolled steel | Standard for most 1950s–1980s US cars |
| 1967 Chevrolet Camaro | Quarter panels | 18 | 1.214 mm | Cold-rolled steel | 18 ga Dynacorn panels match factory press depth |
| 1970 VW Beetle | Body skins | 20 | 0.911 mm | Mild steel | Thinner than US cars of same era |
| Pre-2015 Ford F-150 | Bedsides | 19 | 1.062 mm | Galvanized steel | Steel bed era — 0.043 in galvanized |
| 2015+ Ford F-150 | Cab panels, bed | 18 Al equiv. | 1.0–1.4 mm | 6xxx aluminium | Military-grade aluminium alloy body |
| 2022 Chevy Silverado | Door skins | 20 | 0.911 mm | Bake-hardened steel | Bake-hardenable grade — stronger than mild 20 ga |
| Toyota Tacoma | Rocker panels | 18 | 1.214 mm | Hot-dip galvanized | Heavy-duty rocker protection |
| Jeep Wrangler | Tub / floor (wheel zones) | 16 | 1.518 mm | Mild steel | Heavy gauge for off-road abuse resistance |
| BMW 3-Series | Fenders | ~22 | 0.70 mm | HSLA steel | High-strength low-alloy — do not substitute mild steel |
| Tesla Model 3 | Door skins | ~21 | 0.80 mm | Dual-phase DP steel | DP 980 — equivalent dent resistance to 18 ga mild steel |
| Tesla Model Y | Inner braces | 24 | 0.60 mm | AHSS | Thinnest production body steel in volume production (2026) |
| Audi A8 | B-pillar | 22 | 0.76 mm | Hot-stamped boron | Laser welded — 1500+ MPa strength |
| Rivian R1T | Bed | 14 Al equiv. | 1.5 mm | 5xxx aluminium | Aluminium-intensive EV truck |
| Volvo XC90 | Door outers | 20 | 1.00 mm | TWIP steel | Down-gauged from 1.4 mm HSLA — saves 15 kg/car |
Sources: Anebon Manufacturing Guide, OEM body repair manuals, industry fabrication data. All thicknesses are nominal; actual may vary ±5% by production run and temper.
Before ordering replacement or repair metal, always measure the original panel thickness — here's exactly how to do it
Hold a small magnet to an unpainted edge or inner surface. Steel is strongly magnetic; aluminium is not. Identify material type before measuring — ordering steel repair sheet for an aluminium panel is an expensive mistake.
Locate a spot free of paint, body filler, undercoat or rust. A door jamb, wheel arch inner, or cut edge gives true metal thickness readings. Avoid measuring through paint layers.
A digital vernier caliper at 0.01 mm resolution gives reliable readings. A dedicated sheet metal gauge wheel (go/no-go type) is useful for quick site checks on flat sections. For painted panels, use an ultrasonic thickness gauge.
Thickness varies across a panel due to press stamping. Measure at 3 separate spots and average. A deviation over 0.1 mm may indicate filler build-up, corrosion thinning, or panel deformation rather than gauge variation.
Enter your measured mm value into the Gauge Finder tool at the top of this page to get the closest standard automotive steel gauge. Use the steel chart for most production vehicles; the aluminium chart for premium / EV models.
Order the same gauge ±1 as the original. Thicker replacement metal is harder to form and may not sit flush. Thinner metal reduces rigidity and increases dent risk. For AHSS panels, always confirm the steel grade — gauge alone is not sufficient.
Practical guidance from the fabrication shop floor — for restorers, body shops and custom fabricators
Always confirm steel vs aluminium with a magnet before measuring or ordering. Many modern bonnets, doors and wings are aluminium — ordering steel replacement sheet is an expensive mistake that delays repairs by days.
Modern 20–22 gauge AHSS can be twice as strong as conventional 18 gauge mild steel. Never judge structural integrity by gauge alone — confirm the steel grade. A 0.8 mm DP 980 door skin provides equivalent dent resistance to 1.2 mm mild steel.
For restorations of 1950s–1980s vehicles, 18 gauge mild steel (1.214 mm) is the safest match for original factory panel thickness. Going heavier makes forming harder; going thinner risks long-term oil-canning at highway speeds.
MIG welding 18 gauge: 18–20 volts, 80–100 ipm wire speed. For 22 gauge: drop to 15–17 volts, 60 ipm to avoid burn-through. Never weld 16 gauge floor pan to 20 gauge outer skin without a transition step — mismatched gauges cause burn-through on the thinner material.
Automotive sheet stock is typically sold in 4 ft × 8 ft (1220 × 2440 mm) or 4 ft × 10 ft (1220 × 3050 mm) sheets. Plan your cuts before ordering to minimise wastage — a single 8×4 sheet of 18 gauge steel weighs approximately 11.6 kg.
For floor pans, sills and underbody repair panels, specify hot-dip galvanized (HDG) or G90 zinc-coated sheet. MSG gauge values are the same as mild steel, but the 0.04–0.07 mm zinc coating adds marginally to total measured thickness. Use E-coat primer before welding to restore corrosion protection.
If cracks appear during flanging or English wheel work, anneal the work-hardened area at approximately 1200°F (650°C) for 30 minutes, then air cool. This restores ductility to cold-rolled steel panels that have been over-worked during forming operations.
Never substitute gauge or grade on structural chassis repairs (frame rails, A/B pillars, sill reinforcements) without referencing the vehicle manufacturer's body repair manual. Incorrect gauge in a crumple zone can invalidate crash performance and void insurance. See I-CAR structural repair guidelines for more.
Always calculate total kg of your sheet order before delivery. A heavier-than-expected delivery often means wrong gauge was supplied. Use our MS Sheet Weight Calculator or Aluminium Sheet Weight Calculator to verify quantities.
More free tools and reference guides for fabricators, body shops and engineers
Common questions from body shop technicians, restorers and fabricators about automotive sheet metal gauge