C 10X30 vs MC 10X25
C 10X30 is an C section from the American AISC Shapes Database; MC 10X25 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 437.53 cm³ against 429.34 cm³ of plastic modulus, a difference of 1.9%. MC 10X25 is the lighter of the two at 37.2 kg/m against 44.6 kg/m, a saving of 19.9% on steel weight. Both are about 254 mm deep, so either fits the same construction zone.
| Property | C 10X30 C | MC 10X25 MC | Difference |
|---|---|---|---|
| Mass | 44.6 kg/m | 37.2 kg/m | +19.9% |
| Depth | 254 mm | 254 mm | same |
| Width | 77 mm | 86.6 mm | -11.1% |
| Web thickness | 17.1 mm | 9.7 mm | +76.3% |
| Flange thickness | 11.1 mm | 14.6 mm | -24.0% |
| Area | 56.8 cm² | 47.4 cm² | +19.8% |
| Second moment, major (Iy) | 4,287 cm⁴ | 4,579 cm⁴ | -6.4% |
| Plastic modulus, major (Wpl,y) | 437.53 cm³ | 429.34 cm³ | +1.9% |
| Elastic modulus, major (Wel,y) | 339.21 cm³ | 360.52 cm³ | -5.9% |
| Second moment, minor (Iz) | 163.6 cm⁴ | 301.8 cm⁴ | -45.8% |
| Plastic modulus, minor (Wpl,z) | 61.943 cm³ | 92.587 cm³ | -33.1% |
| Radius of gyration, minor (iz) | 1.7 cm | 2.52 cm | -32.5% |
| Torsion constant (It) | 50.78 cm⁴ | 26.56 cm⁴ | +91.2% |
C 10X30 to AISC Shapes Database v16.0; MC 10X25 to AISC Shapes Database v16.0. Difference is expressed relative to MC 10X25.
How to choose between them
On stiffness, MC 10X25 has the larger second moment of area: 4,579 cm⁴ against 4,287 cm⁴, a difference of 6.4%. This matters more often than the strength comparison, because on normal floor spans deflection rather than bending capacity sets the beam size - so if the two are close on modulus but apart on inertia, the stiffer one is usually the better answer even when it is not the stronger one.
Measured as bending capacity per kilogram of steel, MC 10X25 is the more efficient section: 11.5 against 9.8 cm³ per kg/m, 15.0% better. Over a floor of repeated beams that difference is real tonnage, though it is often outweighed by whichever section the fabricator can actually source.
The two diverge much more about the minor axis: MC 10X25 has 92.587 cm³ of minor-axis plastic modulus against 61.943 cm³, 33.1% more. If the member sees any minor-axis bending, or if it is unrestrained over a long length and lateral-torsional buckling governs, that gap decides the comparison even though the major-axis numbers looked equivalent.
In short, C 10X30 is the stronger section and MC 10X25 is the lighter one; where those are the same section, it is the clear choice, and where they are not, decide on whether your design is governed by capacity or by tonnage.