Steel Flat Bars: Sizes, Weight Chart, Prices & Specifications

Steel Flat Bars: Sizes, Weight Chart, Prices & Specifications<\/h2>

Steel flat bars — also called flat bar steel or flat bar stock — are hot-rolled solid bars with a rectangular cross-section, defined by two dimensions: width and thickness. Flat bar is the most versatile fabrication section in the steel trade: it becomes gussets, brackets, straps, stair strings, lintels, fencing rails, earth bars, and a thousand other details that are cut, drilled, and welded on site. This page is the complete buying reference from Sino East Steel Group — a direct steel structure manufacturer in Tianjin, China, exporting since 1993: flat bar steel sizes, flat bar weight charts, material grades, 2026 FOB price ranges, and the exact way to order flat bars for your project.

1. What Is a Steel Flat Bar?

A steel flat bar is a solid, rectangular bar produced by hot rolling billets into a flat section, then straightened and cut to length. It is specified by width × thickness — for example 50 × 6 mm means 50 mm wide and 6 mm thick — with widths from 12 mm to 200 mm and thicknesses from 3 mm to 25 mm. The large flat faces and straight, parallel edges make flat bar ideal for welding, drilling, bending, and bolting, and it packs flat for economical shipping. Flat bars are supplied as-rolled (black), bright, or galvanized, in 6 m and 12 m lengths or cut to order.

Flat bars are specified to material standards including EN 10025 (S235JR, S275JR, S355JR, S355J2), ASTM A36, ASTM A572 Gr 50, and GB/T 700 / GB/T 1591 (Q235B, Q355B), with dimensional tolerances per EN 10058 and ASTM A6. Every bar is traceable to its heat number and ships with an EN 10204 3.1 mill test certificate.

2. Flat Bar vs Round Bar vs Square Bar: Which Bar Do You Need?

Comparison	Flat Bar	Round Bar	Square Bar
Cross-section	Rectangle (width × thickness)	Solid circle	Solid square
Dimensioning	Two dimensions (w × t)	Single diameter	Single side length
Faces	Two wide flat faces	Curved surface	Four flat faces
Strength	Best in the flat axis — deep section	Equal in all directions	Equal in two axes
Best for	Straps, gussets, brackets, lintels, earth bars	Shafts, pins, anchors, machined components	Keys, pickets, punches, grilles
Typical use	Fabrication details, stair strings, fencing rails	Machine shafts, dowels, reinforcement	Handrails, gates, machine parts

Choose flat bar when you need a wide, thin member that resists bending in one direction or provides a large weld surface. If you need round or square solid stock instead, see our Round Bars and Square Bars pages.

3. Flat Bar Sizes & Dimensions

Standard flat bar steel sizes combine widths from 12 mm to 200 mm with thicknesses from 3 mm to 25 mm. The table below lists the most commonly exported combinations. Custom widths, thicknesses, bright finish, and cut lengths are produced to order.

Width × Thickness (mm)	Imperial Equivalent	Typical Finish	Common Lengths
12 × 3	½″ × ⅛″	Black / bright	6 / 12 m
20 × 3	¾″ × ⅛″	Black / bright	6 / 12 m
25 × 3	1″ × ⅛″	Black / bright	6 / 12 m
30 × 3	1¼″ × ⅛″	Black / bright	6 / 12 m
40 × 4	1½″ × 5/32″	Black	6 / 12 m
40 × 5	1½″ × 3/16″	Black	6 / 12 m
50 × 4	2″ × 5/32″	Black	6 / 12 m
50 × 5	2″ × 3/16″	Black	6 / 12 m
50 × 6	2″ × ¼″	Black	6 / 12 m
60 × 6	2½″ × ¼″	Black	6 / 12 m
65 × 6	2½″ × ¼″	Black	6 / 12 m
75 × 6	3″ × ¼″	Black	6 / 12 m
80 × 8	3¼″ × 5/16″	Black	6 / 12 m
100 × 8	4″ × 5/16″	Black	6 / 12 m
100 × 10	4″ × 3/8″	Black	6 / 12 m
120 × 10	4¾″ × 3/8″	Black	6 / 12 m
150 × 12	6″ × ½″	Black	6 / 12 m
200 × 16	8″ × 5/8″	Black	6 / 12 m
200 × 25	8″ × 1″	Black	6 / 12 m

Width, thickness, and out-of-square tolerances follow EN 10058 and ASTM A6. If your size is not listed, send your requirements — our mills schedule custom flat bar combinations with short lead times.

4. Flat Bar Weight Chart (kg per Metre)

Indicative weights for common flat bar steel sizes, calculated with the standard formula weight = width × thickness × 7.85 / 1000 kg/m (dimensions in mm, 7.85 = steel density). Actual weights per EN 10058 are within ±3% of these values:

Width × Thickness (mm)	Weight (kg/m)	Weight per 6 m (kg)	Weight per 12 m (kg)
25 × 3	0.59	3.53	7.07
30 × 3	0.71	4.24	8.48
40 × 4	1.26	7.54	15.07
40 × 5	1.57	9.42	18.84
50 × 4	1.57	9.42	18.84
50 × 5	1.96	11.78	23.55
50 × 6	2.36	14.13	28.26
60 × 6	2.83	16.96	33.91
65 × 6	3.06	18.37	36.73
75 × 6	3.53	21.20	42.39
80 × 8	5.02	30.14	60.29
100 × 8	6.28	37.68	75.36
100 × 10	7.85	47.10	94.20
120 × 10	9.42	56.52	113.04
150 × 12	14.13	84.78	169.56
200 × 16	25.12	150.72	301.44
200 × 25	39.25	235.50	471.00

Use the flat bar weight chart to estimate tonnage and freight: multiply the kg/m figure by the total length. For example, 1,000 m of 50 × 6 mm flat bar weighs about 2.36 tonnes; 1,000 m of 100 × 10 mm weighs 7.85 tonnes. A 40 ft container holds roughly 22–25 tonnes of flat bar, bundled flat and strapped in uniform-size packs.

5. Flat Bar Material Grades & Surface Options

Option	Specification	Best For
Mild steel	S235JR / Q235B — yield 235 MPa	Straps, brackets, general fabrication
Structural steel	S275JR — yield 275 MPa	Stair strings, lintels, structural details
High-strength steel	S355JR / S355J2 / Q355B — yield 355 MPa	Gussets, heavily loaded brackets
US grades	ASTM A36, ASTM A572 Gr 50	US project specifications
Galvanized	HDG 70–85 µm (ISO 1461) or pre-galvanized	Fencing, earth bars, outdoor use
Surface finish	Black (as-rolled), bright, painted	Fabrication stock, visible metalwork

For electrical earthing and fencing systems, galvanized flat bar is the standard choice. For structural details in humid or coastal regions — much of Africa, the Middle East, and Southeast Asia — specify at least Z275 galvanizing or full HDG. Every batch ships with EN 10204 3.1 mill test certificates.

6. Flat Bar Prices in 2026 (FOB China)

Indicative export pricing from our Tianjin factory (FOB Tianjin Port, 2026):

Product	Indicative Price	MOQ
Mild steel flat bar (S235JR/Q235B), 12–60 mm wide	USD 560–710 per tonne FOB	5 tonnes (mix sizes OK)
Structural flat bar (S275JR/S355JR), wide/heavy sections	USD 590–760 per tonne FOB	5 tonnes
Galvanized flat bar (HDG)	USD 690–890 per tonne FOB	10 tonnes
Cutting to length, drilling, bending, painting	Included or nominal charge	—

Prices move with global hot-rolled coil and billet markets and exchange rates, so treat these as planning ranges. For a firm quotation send your widths, thicknesses, steel grade, quantities, and destination port to paul@sinoeaststeel.com.

7. Flat Bar Applications

• Fabrication details — gusset plates, brackets, cleats, and stiffeners cut and drilled from flat bar stock.
• Stair strings and handrail rails — long, straight flat bar lengths for stair stringers and top rails.
• Lintels and door/window frames — 100 × 8 mm and heavier flat bar as simple structural lintels.
• Fencing rails and gate frames — galvanized flat bar rails between posts, and gate frame members.
• Earth bars and earthing systems — copper-bonded or galvanized flat bar for electrical grounding.
• Straps and tie bars — flat bar straps for truss connections, wall ties, and roof bracing.
• Architectural metalwork — visible flat bar edges for signs, screens, shelving, and furniture frames.

Flat bar is part of our complete steel structure product range — for round or square solid stock, see our Round Bars and Square Bars pages; for tubular profiles, compare our Rectangular Hollow Section and Circular Hollow Section pages.

8. Why Buy Flat Bars Direct from Sino East Steel Group

Sino East Steel Group is a direct China steel structure manufacturer, not a trader. Since 1993 we have operated a 50,000 m² fabrication facility in Tianjin Industrial Park, Daqiuzhuang — China’s largest steel processing hub — with our own bar supply chains, cutting and drilling lines, and hot-dip galvanizing capacity.

• Factory-direct pricing — no middleman; typically 20–40% below regional re-seller prices.
• Certified quality — ISO 9001:2015, ISO 3834-2, EN 1090 EXC3/EXC4, AWS D1.1; mill test certificates on every batch.
• Full size range — 12 mm to 200 mm wide, 3 mm to 25 mm thick, black, bright, or galvanized, lengths to 12 m.
• Value-added processing — cutting, drilling, punching, bending, and galvanizing under one roof.
• Export documentation — invoice, packing list, certificate of origin, EN 10204 3.1 certificates for smooth clearance.
• 100,000+ tonnes annual capacity — standard sizes ship in 1–2 weeks; custom processing in 2–3 weeks.

Before committing to any factory, use our manufacturer verification checklist — we welcome third-party inspection (SGS, BV, TÜV) at any stage.

9. How to Order Flat Bars from China

1. Send your width, thickness, steel grade, finish, length, quantity, and destination port.
2. Receive an itemized quotation within 24–48 hours (FOB/CIF).
3. Confirm tolerance class, coating, and mill certificate requirements.
4. We produce and test (SGS/BV/TÜV inspection optional).
5. We ship FCL from Tianjin with full export documentation.

For complete projects — flat bar details plus structural steel — see our procurement guide for importers.

10. Flat Bar Fabrication & Design Notes

Flat bar is the most forgiving section to fabricate: it welds with simple fillet welds on the flat faces, drills and punches cleanly, and bends in the flat plane up to moderate thicknesses. Three practical rules: (1) when flat bar is used as a lintel or strap, orient the deep dimension (width) vertically so it resists bending in the correct direction; (2) for welding, specify the edge preparation when thickness exceeds 12 mm and full-penetration welds are required; (3) for galvanizing, avoid fully enclosed box sections formed from flat bar — provide vent holes so the coating reaches internal surfaces. When flat bar is cut to make gussets and brackets, nesting the parts on the bar minimizes waste — send us your cutting list and we will optimize the layout.

For earthing systems, confirm the cross-section area required by your electrical code and the coating specification (galvanized or copper-bonded). Our engineers can provide cutting lists, drilling patterns, and bending details free of charge with your quotation request.

11. Packing, Shipping & Delivery

Flat bars are bundled flat in uniform-size packs, strapped with steel bands, and loaded into 40 ft containers or break-bulk holds at Tianjin Port. Each bundle carries a tag with your project name, width, thickness, grade, and length for easy site sorting. Standard export documentation — commercial invoice, packing list, bill of lading, certificate of origin, and EN 10204 3.1 mill test certificates — is provided with every shipment.

Typical transit times: 3–4 weeks to the Middle East (Jebel Ali), 4–6 weeks to East and West Africa (Mombasa, Lagos), 4–5 weeks to Europe, and 3–5 weeks to North America. For full-project shipping details, read our international shipping and installation guide.

12. Flat Bar FAQ

Q: What are the standard flat bar steel sizes?
A: Standard widths run from 12 mm to 200 mm and thicknesses from 3 mm to 25 mm — for example 25 × 3, 50 × 5, 50 × 6, 100 × 8, 100 × 10, and 150 × 12 mm. Lengths are 6 m or 12 m; custom cut lengths available.

Q: How do I calculate flat bar weight per metre?
A: Use the formula width × thickness × 7.85 / 1000 kg/m. For example, 50 × 6 mm flat bar weighs about 2.36 kg/m and 100 × 10 mm about 7.85 kg/m. Our weight chart above covers the full range.

Q: How much does flat bar cost in 2026?
A: Indicative FOB China prices are USD 560–710 per tonne for mild steel flat bar, USD 590–760 for structural grades, and USD 690–890 per tonne galvanized. Freight and duty vary by destination.

Q: Which steel grades are available for flat bars?
A: S235JR, S275JR, S355JR, and S355J2 per EN 10025; Q235B and Q355B per GB/T 700 and GB/T 1591; ASTM A36 and A572 Gr 50 for US projects.

Q: What is the tolerance on flat bar dimensions?
A: Per EN 10058 and ASTM A6, width and thickness tolerances apply to as-rolled black bar; bright drawn flat bar is held to tighter tolerances for exact-section work.

Q: Can flat bars be galvanized?
A: Yes — hot-dip galvanized (HDG 70–85 µm per ISO 1461) for fencing, earthing, and coastal structures, or pre-galvanized for lighter-duty use.

Q: Can you supply flat bar cut, drilled, or bent to my drawing?
A: Yes. We cut, drill, punch, and bend flat bar to your shop drawings — including gusset profiles, anchor plates, and stair strings — with nominal or included processing cost.

Q: Do you provide mill test certificates?
A: Yes — every batch ships with EN 10204 3.1 mill test certificates showing chemical composition and mechanical properties, plus certificate of origin and full export documentation.

Q: How do I get a flat bar quotation?
A: Email your width, thickness, grade, finish, length, quantity, and destination port to paul@sinoeaststeel.com or message us on WhatsApp — you will receive an itemized FOB/CIF quotation within 48 hours.