What Thickness Tolerance Applies to Cold Rolled and Hot Rolled Steel Sheet?
What Thickness Tolerance Applies to Cold Rolled and Hot Rolled Steel Sheet?
Direct answer: thickness tolerance is set by the governing standard, the thickness band and the width - there is no single plus-minus number that applies across a product family. Cold rolled sheet is held to tighter limits than hot rolled, and for both, tolerance widens as the material gets thicker and wider. A purchase order should cite the standard and the tolerance class, not just a headline figure.
| Product | Governing standard | How tolerance is expressed |
|---|---|---|
| Cold rolled sheet and coil | ASTM A568 / EN 10131 | Tighter limits, banded by thickness and width |
| Hot rolled sheet and coil | ASTM A1011 / EN 10051 | Wider limits, widening with thickness |
| Hot-dip coated sheet | ASTM A924 / EN 10143 | Base steel tolerance plus a coating allowance |
| Cut-to-length plate | ASTM A6 / EN 10029 | Separate thickness and flatness tables |
Why a blanket plus-minus figure is a risky promise
A supplier who quotes a single figure such as plus or minus 0.02 mm for everything is either quoting the best case at the thinnest, narrowest end of the range, or has not checked the table. The same nominal thickness at a wider width carries a looser tolerance in every standard, because crown control across a wider strip is harder.
Write the requirement as: nominal thickness, the standard, and the tolerance class where the standard offers one. That combination is checkable at inspection; a bare number is not.
How tolerance affects your yield and your cost
Thickness tolerance is a commercial lever, not just a quality note. Material rolled toward the minus side of the allowance yields more square metres per tonne - attractive until forming or structural demands need the section to hold. Material at the plus side costs more per square metre but protects the finished part.
Decide which side you can live with before the order, and say so. It is far easier to agree a target than to argue about a delivered coil.
Where the measurement is taken
Standards define the measurement position - typically a set distance from the edge, at a defined number of points across the width. Two inspectors can reach different verdicts on the same coil by measuring in different places, which is why the standard citation matters as much as the number.
