Standard mild steel plate thickness chart

As a foundational material in modern industry, low-carbon steel plate thickness standards directly influence structural performance, fabrication efficiency, cost control, and engineering safety.

This guide consolidates:

National standards (GB series)

International specifications such as ISO 9445

American standards including ASTM A6 and ASTM A1008

It provides a structured reference for engineering design, procurement decisions, and manufacturing control.

Standard Mild Steel Plate Thickness Chart

In industrial terminology:

Sheet → thickness < 3.0 mm

Plate → thickness ≥ 3.0 mm

Below is a commonly referenced mild steel (MS) thickness and weight chart, calculated using the standard steel density of 7,850 kg/m³.

Note: Actual weight may vary slightly due to rolling tolerances.

Low-Carbon Steel Plate Thickness Classification System

Low-carbon steel plates are classified by production process and thickness range.

Cold-Rolled Low-Carbon Steel Plate

Thickness Range:
0.3 mm – 3.5 mm (GB standards)
Extended to 0.2 mm for deep-drawing grades (e.g., DC06)

Key Characteristics:

Surface roughness: Ra ≤ 3.2 μm

Dimensional tolerance: ±0.05 mm to ±0.30 mm

High surface flatness and uniformity

Excellent formability

Typical Applications:

Automotive body panels

Home appliance housings

Precision stamped components

Electrical cabinets

Cold-rolled sheets follow standards such as ASTM A1008.

Hot-Rolled Low-Carbon Steel Plate

Thickness Range:
1.2 mm – 60 mm (GB/T 709 equivalent system)

Sub-classification:

Thin plate (1.2–3 mm)
Roof trusses, light structural frames

Medium plate (3–25 mm)
Machinery bases, bridge supports, ship bulkheads

Thick plate (>25 mm)
Mining equipment, pressure vessels, heavy structures

Hot-rolled plates are commonly governed by ASTM A6 for dimensional tolerances.

Advantages:

Cost-effective for structural use

Suitable for welding and machining

High load-bearing capacity

Pickled Low-Carbon Steel Plate

Thickness Range:
0.3 mm – 6.0 mm

Pickled plates are hot-rolled steel sheets with oxide scale removed through acid treatment.

Surface Roughness: Ra 0.6–1.9 μm

Advantages:

Improved paint adhesion

Better corrosion resistance

Cleaner surface for fabrication

Typical Uses:

Chemical pipelines

Automotive chassis components

Structural parts requiring coating

How to Calculate Mild Steel Plate Weight

Accurate weight calculation is essential for:

Freight estimation

Crane load planning

Structural load calculation

Cost control

Metric Formula (Kilograms)

Weight (kg)=Length(m)×Width(m)×Thickness(mm)×7.85\textbf{Weight (kg)} = Length (m) \times Width (m) \times Thickness (mm) \times 7.85Weight (kg)=Length(m)×Width(m)×Thickness(mm)×7.85

Imperial Formula (Pounds)

Weight (lb)=Length(in)×Width(in)×Thickness(in)×0.2836\textbf{Weight (lb)} = Length (in) \times Width (in) \times Thickness (in) \times 0.2836Weight (lb)=Length(in)×Width(in)×Thickness(in)×0.2836

These formulas are derived from the standard density of carbon steel.

Understanding Rolling Tolerances

A “10 mm plate” is not guaranteed to measure exactly 10.00 mm.

According to international tolerance standards such as:

ISO 9445

ASTM A6

Rolling tolerances allow thickness variation.

For example:

A nominal 10 mm plate may measure between 9.8 mm and 10.2 mm (depending on width and grade).

Engineering Recommendation:

For precision assemblies, always allow:

±0.2 mm to ±0.5 mm design margin

Additional machining allowance if tight tolerances are required

Failure to account for rolling tolerance can cause misalignment, welding distortion, or structural deviation.

Key Selection Points for Engineering & Procurement

When selecting mild steel plate thickness:

Define load-bearing requirements

Confirm applicable standard (GB / ASTM / ISO)

Verify rolling tolerance class

Confirm flatness requirement

Calculate theoretical weight for budgeting

Consider corrosion allowance if applicable

FAQ

What thickness is considered steel sheet?
Steel thinner than 3 mm is generally classified as sheet.

What thickness is considered steel plate?
Steel 3 mm and above is classified as plate.

How do you calculate mild steel plate weight?
Multiply length × width × thickness × 7.85 (metric).

Do steel plates have thickness tolerance?
Yes. International standards such as ASTM A6 define allowable rolling tolerances.

What is the density of mild steel?
Approximately 7,850 kg/m³.

Summary

Low-carbon (mild) steel plate thickness ranges from ultra-thin cold-rolled sheets (0.2 mm) to heavy structural plates (60 mm). Thickness classification depends on production process (cold rolled, hot rolled, pickled), while dimensional tolerances are governed by standards such as ASTM A6 and ISO 9445.

Accurate thickness selection and tolerance consideration are critical for structural integrity, fabrication precision, and cost optimization.