Structural Beam Load Calculator
Structural Calculation Results
Dead Load (kN/m)-
Live Load (kN/m)-
Total UDL (kN/m)-
Maximum Bending Moment (kNm)-
Minimum Section Modulus (cm³)-
Suggested Beam Size-
Common Steel Beam Sizes (Universal Beams)
| Section | Depth (mm) | Weight (kg/m) | Section Modulus (cm³) | Typical Span |
|---|---|---|---|---|
| 152x89x16 UB | 152 | 16 | 109 | Up to 2m |
| 178x102x19 UB | 178 | 19 | 146 | Up to 2.5m |
| 203x133x25 UB | 203 | 25 | 234 | Up to 3m |
| 254x146x31 UB | 254 | 31 | 353 | Up to 4m |
| 305x165x40 UB | 305 | 40 | 560 | Up to 5m |
| 356x171x51 UB | 356 | 51 | 794 | Up to 6m |
These are indicative only. All structural calculations must be verified by a qualified structural engineer for Building Regulations compliance.
Structural Engineer Costs
Simple Beam Calc
£200-£400
Loft Conversion
£500-£1,000
Extension
£800-£2,000
How to Use This Calculator
1
Enter opening width
Input the clear span of the opening in millimetres. This is the distance between supporting walls or columns.
2
Select wall and floor details
Choose the wall type, number of floors supported above, and roof type to determine the loading.
3
Enter floor span
Input the span of floor joists bearing onto the wall, measured perpendicular to the beam.
4
Review beam suggestion
The calculator shows estimated loads, bending moment, and a suggested beam size. Always have a structural engineer verify.
Frequently Asked Questions
Do I need a structural engineer?
Yes, for any work involving load-bearing walls, steel beams, foundations, or structural alterations. Building Control will require structural calculations signed by a qualified engineer. DIY structural calculations are not accepted for Building Regulations approval. A structural engineer typically costs £200-£2,000 depending on project complexity.
What is the difference between dead load and live load?
Dead load is the permanent weight of the structure itself (walls, floors, roof, finishes). Live load is the variable weight of occupants, furniture, and environmental loads (wind, snow). UK Building Regulations (BS EN 1991) specify minimum live loads: 1.5 kN/m² for domestic floors, 0.75 kN/m² for domestic roofs.
How wide an opening can I create in a wall?
For standard domestic construction, openings up to about 3-4 metres in load-bearing walls are common using steel beams. Wider openings require larger beams and may need additional padstones or spreader plates. Non-load-bearing walls can have wider openings with lighter lintels. Always get engineer approval.
What size steel beam do I need?
Beam size depends on: span (opening width), load above (floors, roof, walls), and loading type. As a very rough guide: up to 2m span = 152mm deep UB, 2-3m = 203mm, 3-4m = 254mm, 4-5m = 305mm. These are indicative only and must be verified by a structural engineer.
Do I need Building Regulations for removing a wall?
Yes. Removing or altering any load-bearing wall requires Building Regulations approval. You will need structural calculations, a Building Regulations application (or use a competent persons scheme), and inspections during construction. Fines for non-compliance can be significant, and unapproved work can cause issues when selling.
What are padstones and why do I need them?
Padstones are concrete or stone blocks placed at each end of a steel beam to spread the concentrated load onto the supporting wall. Without padstones, the point load from the beam could crush the masonry below. Typical padstone size is 450x225x100mm in dense concrete (minimum 35 N/mm² strength).
Official Sources & References
Data verified against official UK government sources. Last checked April 2026.