Steel Flat Product Sizes
This tool covers the full gauge and thickness range of steel flat products, from thin-gauge cold rolled coil (0.18mm) through hot rolled coil, plate (thin, medium and heavy), quarto plate, and the semi-finished products slab and thin slab. Coated products — galvanised, tinplate and pre-painted (PPGI) — are also covered. Use the lookup to identify which product category a given thickness falls into, or browse the spectrum and product cards. Width ranges are covered in the separate section below. For a broader treatment of flat-rolled steel markets, pricing and applications, see Flat-Rolled Steel — Essentials.
Note on terminology: gauge is the more precise technical term used in mill practice and trade specifications; thickness is the more widely understood everyday term. Both are used interchangeably on this page.
● Thickness / gauge lookup
Gauge / thickness — logarithmic scale 0.1mm to 400mm
Slab
Semi-finishedRectangular semi-finished continuously cast product. The primary feedstock for hot strip mills, plate mills, and Steckel mills. Conventional continuous casting produces slabs typically 150–400mm thick and up to ~2,100mm wide. Length varies by caster design and downstream requirements.
Chemical composition controlled for downstream rolling. Surface inspected and scarfed or ground to remove cracks and segregation. Internal soundness assessed by ultrasound for plate grades.
Continuously cast via tundish through an oscillating copper mould. Solidified strand straightened and cut to length by torch cutter or pendulum shear. Soft reduction applied near the meniscus on modern casters to improve centreline quality.
Slab thickness determines the maximum achievable reduction ratio on the downstream rolling mill. Wide slab (>1,800mm) requires a wide-strip or wide-plate mill. Conventional slab is a semi-finished product and is not normally sold as a finished steel product except in certain trade flows.
Thin Slab
Semi-finishedThin slab casting produces a strand typically 50–90mm thick which passes directly into an in-line rolling mill (CSP, ESP, ISP, or Conroll process) without a separate reheating furnace. The thin slab is not a marketed steel product; it exists only as work-in-progress within an integrated casting-rolling line.
Not applicable as a standalone product. The downstream hot rolled coil quality is constrained by thin slab metallurgy: segregation and inclusion content are harder to control at high casting speeds, limiting applicability to some higher grades.
Cast on a thin slab caster (liquid core reduction to ~50mm on entry to roughing mill). Passed through a tunnel furnace for temperature homogenisation then rolled in-line to finished HRC gauge. Process achieves 1mm+ routinely; advanced ESP lines achieve sub-1mm.
Thin slab casting and rolling (TSCR) is commercially established at Nucor (CSP), ArcelorMittal (CSP), and others. The ESP (Endless Strip Production) process by Arvedi/Primetals eliminates coiling entirely, casting and rolling in a single continuous strand.
Plate
FinishedHot rolled flat product in discrete lengths (quarto plate) or coil at the thinner end of the range. Plate mills are reversing mills (one or two stand, four-high) producing wide product in straight lengths. Plate overlaps with heavy gauge HRC coil at the thin end and with structural applications throughout.
Structural (S235–S690 and above); pressure vessel (EN 10028); shipbuilding (Lloyd’s, DNV, ABS, NK); wear-resistant (Hardox equivalent); linepipe grades (API 5L / ISO 3183); offshore and wind tower grades.
Reheated slab rolled on a reversing plate mill with controlled rolling and accelerated cooling (TMCP) for higher-strength grades. Normalised, quenched and tempered, or TMCP depending on grade.
Thin plate: 3–35mm. Medium plate: 35–90mm (boundary somewhat arbitrary). Heavy plate: 90–150mm; the 120–150mm range represents the practical maximum for most plate mills. Shipbuilding plate is typically 10–30mm, mostly in the 20–30mm range. Plate for large diameter pipe: 15–40mm (see Large Diameter Pipe Planner).
Hot Rolled Coil (HRC)
FinishedThe primary hot rolled flat product, produced on a hot strip mill (HSM) from slab or thin slab. The starting material for CRC, coated products, and many direct-use structural and engineering applications. Supplied as pickled and oiled (P&O) or with mill scale.
Structural grades (S235, S275, S355 to EN 10025); pressure vessel grades; wear-resistant; high-strength. HSLA grades widely used in construction, automotive frames, and pipelines.
Reheated slab reduced in roughing stands then finished in a 6- or 7-stand finishing train. Coiled on a downcoiler at 550–750°C. Traditional HSM minimum gauge is ~1.5mm (1mm+ on advanced mills). Thin slab casting and rolling (CSP/ESP) achieves 1mm+ routinely.
At 1–3mm, HRC overlaps with CRC; at 3–6mm, HRC overlaps with thin plate. Above ~12mm, coiled plate becomes more common. The Steckel mill route achieves 2mm+ but with limitations on surface quality for prime applications.
Cold Rolled Coil (CRC)
FinishedCold rolled from hot rolled coil (HRC) by tandem cold mill or reversing mill, reducing thickness by 50–80%. The thinnest flat rolled steel product in regular production. Supplied as full-hard (as-rolled) or annealed and temper-rolled for forming applications.
Structural grades (DC01–DC06 to EN 10130); high-strength low-alloy; dual-phase and advanced high-strength steels (AHSS) for automotive. Surface quality grades: unexposed (U), exposed (E).
Pickled and oiled HRC reduced on a 4- or 5-stand tandem cold mill or a reversing cold mill (RCM). Full-hard CRC is annealed in a batch anneal (BAF) or continuous anneal line (CAL), then temper rolled to achieve flatness and surface texture.
0.18–0.3mm is thin gauge and commands a significant price premium. The 0.8–1.5mm range overlaps with thin HRC; product choice depends on surface quality and forming requirements.
Galvanised (GI / HDG)
FinishedCold rolled base metal hot-dip galvanised (zinc coated) for corrosion resistance. The dominant coated flat product globally. Used in construction (roofing, cladding, purlins, framing), automotive (unexposed panels), appliances, and packaging.
EN 10346 (structural and forming grades DX51D–DX57D, S220GD–S550GD). Coating mass specified in g/m² total both sides (Z100, Z200, Z275, Z350, Z450). Higher coating mass for more aggressive environments.
CRC base (or occasionally P&O HRC for structural grades) processed through a continuous hot-dip galvanising line (CGCL): clean, anneal in-line in a vertical furnace, coat in molten zinc bath, air-knife wipe to coating mass, skin pass roll.
Gauge is base metal thickness, not including zinc coating. Total product thickness is marginally greater. Galvalume / Zincalume (55% Al-Zn alloy coating) offers superior corrosion resistance at equivalent coating mass. For a detailed treatment of galvanising line processes, see: Air Knife & Coating Mass Control, Temper Rolling & Tension Levelling, and Coil Winding — Stress & Failure Modes.
Pre-Painted / Organic Coated (PPGI)
FinishedGalvanised or Galvalume substrate with organic coating (paint, primer, or laminate) applied on a continuous coil coating line. Widely used in construction (roofing, cladding, composite panels) and appliances (white goods). Also known as colour-coated steel or pre-coated steel.
EN 10169. Coating systems: polyester (PE), silicon-modified polyester (SMP), polyvinylidene fluoride (PVDF) for premium durability, and plastisol for deep profile. Paint film thickness 15–200 microns depending on system.
Galvanised or Galvalume coil processed through a coil coating line (CCL): clean, pretreat (chromate or chrome-free), prime coat, finish coat (top and back), oven cure at peak metal temperature (PMT) typically 215–232°C.
Gauge is base metal before coating. Total product thickness including paint system is fractionally greater. Substrate zinc coating and paint system specification are both critical to service life; gauge alone does not define the product. The galvanised substrate entering the coil coating line is typically skin-pass rolled for flatness; see Temper Rolling & Tension Levelling in Galvanising Lines.
Tinplate
FinishedVery thin cold rolled steel with a thin electrolytic tin coating on both surfaces. The primary material for food and beverage cans, aerosols, and general line packaging. One of the thinnest steel products in commercial production.
EN 10202 / ASTM A623. Temper grades T1–T5 (single reduced) and DR (double reduced, T6–T8) for harder, thinner product. Tin coating mass: E1.0 to E11.2 g/m² per side. Low-tin or tin-free steel (TFS / ECCS) used where lacquering replaces tin.
Thin CRC base metal further reduced on a tandem cold mill to tinplate gauge. Electrolytically tinned on a continuous electroplating line (ETL). Alternatively, double reduced (DR) tinplate uses a second cold reduction after annealing to achieve thinner gauges at higher hardness.
Gauge given is base metal. Tin coating adds negligibly to total thickness. The tinplate market is dominated by integrated producers with dedicated ETL lines; it is not accessible from a standard CRC line.
Width Ranges
Width classification for hot rolled flat products reflects mill design and downstream use. The boundaries between strip categories are conventional rather than standardised; some producers use different cut-offs. Beyond ~1,800–2,000mm width, coiling is not practical and the product must be rolled as wide plate on a plate mill.
| Category | Typical width range | Notes |
|---|---|---|
| Wide (standard) hot rolled strip | 900–1,800mm | Dominant category. Most hot strip mills (HSM) are designed for this range. Maximum of ~1,800mm on most mills; some wide-strip mills reach 2,000mm. |
| Medium strip | 400–800mm | Produced on medium strip mills or slit from wide coil. Used for tubemaking, roll forming, and general fabrication. |
| Narrow strip / skelp | 200–500mm | Skelp is narrow strip used as feedstock for ERW pipe and tube welding. Also used for cold roll forming of small sections. |
| Wide plate | >1,800–2,000mm | Requires a plate mill. A small number of plate mills reach 2,100mm; this is the practical maximum for flat-rolled steel. Coiled product above ~2,000mm is very rare. |
| Strip / sheet cut-off | ~500–600mm | Below ~500–600mm width, flat product is conventionally classified as strip; above this it is sheet or plate. |
Frequently Asked Questions
What is the difference between HRC and CRC?
Hot rolled coil (HRC) is produced directly from a slab on a hot strip mill at temperatures above the steel’s recrystallisation point (~900°C+). Cold rolled coil (CRC) is produced by further reducing HRC at room temperature on a cold mill, achieving thinner gauges and a much smoother, more precise surface. CRC is the feedstock for galvanised, tinplate, PPGI, and many automotive applications.
What gauge is cold rolled coil?
CRC is produced in gauges from approximately 0.18mm to 3.0mm. The bulk of the market is in the 0.5–1.2mm range. Below 0.3mm is thin gauge and commands a significant price premium. Above ~1.5mm, CRC competes with thin HRC depending on surface quality requirements.
What thickness is plate?
Plate starts at approximately 3mm, though few facilities produce plate below 4–6mm. The bulk of plate tonnage is in the 12–35mm range. Thin plate is conventionally 3–35mm; medium plate 35–90mm; heavy plate 90–150mm. The thickest plate produced commercially is in the 120–150mm range.
What is quarto plate?
Quarto plate is plate produced on a one- or two-stand four-high reversing plate mill, in discrete straight lengths rather than coil. It is typically wide (up to ~4,000mm on the widest mills) and covers the full plate thickness range. The term distinguishes it from coiled plate (which is thinner, typically up to ~25mm) and from hot rolled coil produced on a strip mill.
What is the difference between slab and thin slab?
Conventional continuously cast slab is typically 150–400mm thick and is reheated in a walking beam furnace before rolling on a hot strip or plate mill. Thin slab is cast at 50–90mm thickness and passes directly into an inline rolling mill (CSP, ESP) via a tunnel furnace, without a separate reheating step. Thin slab is not a marketed product; it exists only as work-in-progress within an integrated casting-rolling line.
What gauge is tinplate?
Tinplate is produced in base metal gauges from approximately 0.13mm to 0.49mm, with the bulk of commercial production in the 0.17–0.36mm range. Double reduced (DR) tinplate uses a second cold rolling pass to achieve the thinnest and hardest gauges. The tin coating itself is very thin (typically 1–11 g/m² per side) and adds negligibly to total thickness.
What is PPGI?
PPGI (pre-painted galvanised iron, also called pre-coated or colour-coated steel) is a galvanised or Galvalume substrate with an organic coating — paint, primer, or laminate — applied on a coil coating line. It is predominantly used in construction (roofing and cladding) and appliances. The gauge range is 0.18–1.5mm base metal; thicker substrate is used for industrial and structural applications.
Air Knife & Coating Mass Control in Galvanising Lines — how zinc coating mass is set and controlled.
Temper Rolling & Tension Levelling in Galvanising Lines — skin-pass rolling, elongation, and flatness correction.
Coil Winding in Galvanising Lines — Stress & Failure Modes — coiling tension, edge wave, and coil collapse.
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