Beam Span Estimator
Preliminary rule-of-thumb span sizing
Preliminary sizing only, based on rule-of-thumb span-to-depth ratios. Every structural element must be designed and verified by a qualified structural engineer.
m
Distance between supports, in meters.
Rules of thumb used
| Element | Depth |
|---|---|
| Timber floor joist | L / 15 |
| Timber beam / girder | L / 12 |
| Steel beam (IPE) | L / 20 |
| Reinforced concrete beam | L / 12 |
| RC flat slab | L / 28 |
Suggested preliminary size
Suggested depth
—
Suggested width
—
Slab thickness applies to a 1 m strip — no width to size.
Depths are rounded up to common increments; widths are indicative proportions.