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

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

Steel square bars — also called square bar steel or square rod — are hot-rolled solid bars with an equal-sided square cross-section, valued for their flat faces, sharp edges, and equal strength in two perpendicular axes. Square bar is the standard material for keys, punches, handrail pickets, grilles, machine details, and structural fabrication where a flat bearing face matters. This page is the complete buying reference from Sino East Steel Group — a direct steel structure manufacturer in Tianjin, China, exporting since 1993: square bar steel sizes, square bar weight charts, material grades, 2026 FOB price ranges, and the exact way to order square bars for your project.

1. What Is a Steel Square Bar?

A steel square bar is a solid bar with four equal sides and right-angle corners, produced by hot rolling billets through square passes, then straightened and cut to length. It is defined by a single dimension — the side length — which simplifies specification and inspection. Sizes run from 8 mm fine picket bar up to 260 mm heavy forging and machining stock, supplied as-rolled (black), bright drawn, or galvanized, in 6 m and 12 m lengths or cut to order. The flat faces make square bar easy to stack, clamp, weld, and bolt, and it provides a natural bearing surface where parts meet at 90 degrees.

Square 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 10059 and ASTM A6. Every bar is traceable to its heat number and ships with an EN 10204 3.1 mill test certificate.

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

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

Choose square bar when you need flat bearing faces and right angles; choose round bar when the part will be turned or rotates. If you need a wide, thin section instead, see our Flat Bars page, or our Round Bars page for solid cylindrical stock.

3. Square Bar Sizes & Dimensions

Standard square bar steel sizes run from 8 mm to 260 mm side length in regular increments. The table below lists the most commonly exported sizes with typical availability. Custom sizes, bright drawn finish, and cut lengths are produced to order.

Side (mm)	Imperial Equivalent	Typical Finish	Common Lengths
8	5/16″	Black / bright	6 / 12 m
10	3/8″	Black / bright	6 / 12 m
12	1/2″	Black / bright	6 / 12 m
16	5/8″	Black / bright	6 / 12 m
20	3/4″	Black / bright	6 / 12 m
25	1″	Black	6 / 12 m
30	1¼″	Black	6 / 12 m
40	1½″	Black	6 / 12 m
50	2″	Black	6 / 12 m
60	2½″	Black	6 / 12 m
80	3¼″	Black	6 / 12 m
100	4″	Black	6 / 12 m
120	4¾″	Black	6 / 12 m
150	6″	Black	6 / 12 m
200	8″	Black	6 / 12 m
260	10¼″	Black	6 / 12 m

Side and out-of-square tolerances follow EN 10059 and ASTM A6. For sizes above 60 mm, confirm the tolerance class with your fabricator — bright drawn square bar is available where exact section is critical.

4. Square Bar Weight Chart (kg per Metre)

Indicative weights for common square bar steel sizes, calculated with the standard formula weight = a² × 7.85 / 1000 kg/m (a = side length in mm, 7.85 = steel density). Actual weights per EN 10059 are within ±3% of these values:

Side (mm)	Weight (kg/m)	Weight per 6 m (kg)	Weight per 12 m (kg)
10	0.79	4.71	9.42
12	1.13	6.78	13.56
16	2.01	12.06	24.11
20	3.14	18.84	37.68
25	4.91	29.44	58.88
30	7.07	42.39	84.78
40	12.56	75.36	150.72
50	19.63	117.75	235.50
60	28.26	169.56	339.12
80	50.24	301.44	602.88
100	78.50	471.00	942.00
120	113.04	678.24	1,356.48
150	176.63	1,059.75	2,119.50
200	314.00	1,884.00	3,768.00
260	530.66	3,183.96	6,367.92

Use the square bar weight chart to estimate tonnage and freight: multiply the kg/m figure by the total length. For example, 1,000 m of 40 mm square bar weighs about 12.56 tonnes; 1,000 m of 12 mm picket bar weighs only 1.13 tonnes. A 40 ft container holds roughly 22–25 tonnes of square bar, bundled and strapped in uniform-size packs.

5. Square Bar Material Grades & Surface Options

Option	Specification	Best For
Mild steel	S235JR / Q235B — yield 235 MPa	Pickets, grilles, general fabrication
Structural steel	S275JR — yield 275 MPa	Structural details, heavier members
High-strength steel	S355JR / S355J2 / Q355B — yield 355 MPa	Keys, punches, highly loaded members
US grades	ASTM A36, ASTM A572 Gr 50	US project specifications
Galvanized	HDG 70–85 µm (ISO 1461) or pre-galvanized	Fencing, handrails, outdoor use
Surface finish	Black (as-rolled), bright drawn, peeled	Machining stock, tight-tolerance fits

For handrails, gates, and outdoor grilles, galvanized square bar gives decades of service with minimal maintenance. For keys and machine parts, bright drawn bar provides better dimensional consistency and a cleaner surface. Every batch ships with EN 10204 3.1 mill test certificates.

6. Square Bar Prices in 2026 (FOB China)

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

Product	Indicative Price	MOQ
Mild steel square bar (S235JR/Q235B), 8–50 mm	USD 560–710 per tonne FOB	5 tonnes (mix sizes OK)
Structural square bar (S275JR/S355JR), 50–260 mm	USD 590–760 per tonne FOB	5 tonnes
Galvanized square bar (HDG)	USD 690–890 per tonne FOB	10 tonnes
Bright drawn / peeled finishes	USD 760–1,010 per tonne FOB	10 tonnes
Cutting to length, drilling, threading	Included or nominal charge	—

Prices move with global billet and scrap markets and exchange rates, so treat these as planning ranges. For a firm quotation send your side sizes, steel grade, lengths, quantities, and destination port to paul@sinoeaststeel.com.

7. Square Bar Applications

• Handrail pickets and balusters — galvanized square bar pickets in residential and commercial railing systems.
• Gates, grilles, and security screens — welded square bar frames and infills with clean right-angle joints.
• Keys, pins, and punches — square bar is the standard stock for square keys, alignment pins, and blanking punches.
• Machine details and tooling — slides, stops, guide rails, and fixture bases machined from square stock.
• Structural details — bracing cleats, gusset edges, and connection details in steel frames.
• Architectural metalwork — square bar frames for signs, screens, balustrades, and furniture.
• Forging and machining stock — larger sizes for forgings, dies, and heavy machined components.

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

8. Why Buy Square 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, drawing and cutting 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 — 8 mm to 260 mm side, black, bright, or galvanized, lengths to 12 m.
• Value-added processing — cutting, drilling, threading, 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 Square Bars from China

1. Send your side size, 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 — square bar plus structural steel — see our procurement guide for importers.

10. Square Bar Fabrication & Design Notes

Square bar welds cleanly because the flat faces accept fillet welds without edge preparation up to moderate sizes. For picket-and-rail assemblies, spacing is typically 100–120 mm for building balustrades and 150 mm for security fencing — check your local code. When square bar is used for torsion members or keys, the sharp corners concentrate stress, so round the edges where fatigue matters. For bending, mild steel square bar forms reliably cold up to about 20 mm side; larger sizes require hot bending — our shop can handle both. When square bar is machined into keys or punches, allow 0.5–1.0 mm cleanup per face on black bar.

For galvanized outdoor structures, confirm the coating mass per EN ISO 1461 and the minimum average thickness (70 µm for sections above 6 mm). Our engineers can provide cutting lists, bending details, and full fabrication schedules free of charge with your quotation request.

11. Packing, Shipping & Delivery

Square bars are bundled 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, side size, 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. Square Bar FAQ

Q: What are the standard square bar steel sizes?
A: Standard side sizes run from 8 mm to 260 mm in regular increments (10, 12, 16, 20, 25, 30, 40, 50, 60, 80, 100, 120, 150, 200, 260 mm). Lengths are 6 m or 12 m; custom cut lengths available.

Q: How do I calculate square bar weight per metre?
A: Use the formula a² × 7.85 / 1000 kg/m. For example, a 25 mm square bar weighs about 4.91 kg/m and a 50 mm bar about 19.63 kg/m. Our weight chart above covers the full range.

Q: How much does square bar cost in 2026?
A: Indicative FOB China prices are USD 560–710 per tonne for mild steel square bar, USD 590–760 for structural grades, and USD 690–890 per tonne galvanized. Machined finishes cost more.

Q: Which steel grades are available for square 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 square bar dimensions?
A: Per EN 10059 and ASTM A6, normal tolerances apply to as-rolled black bar; bright drawn bar is held to tighter dimensional and out-of-square tolerances.

Q: Can square bars be galvanized?
A: Yes — hot-dip galvanized (HDG 70–85 µm per ISO 1461) for outdoor fencing, handrails, and coastal structures, or pre-galvanized bright bar.

Q: What is the difference between black and bright drawn square bar?
A: Black bar is as-rolled with mill scale and normal tolerances; bright drawn bar is cold-drawn to tighter tolerances with a clean, smooth surface — preferred for keys, punches, and visible metalwork.

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 square bar quotation?
A: Email your side size, 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.