RSJ Beam Weight Calculator: How Heavy Is Your Steel Beam? 2026
Ordering an RSJ beam without knowing its weight is like buying a car without checking its dimensions. The mass of rolled steel joists affects everything from delivery vehicle selection and crane hire to whether four builders can safely carry it through your kitchen. This guide gives you a simple formula, a complete weight-per-metre chart, total weights for popular lengths, and practical advice on handling and delivery. For a more detailed reference, see our dedicated RSJ beam weight per meter chart.
Why RSJ Beam Weight Matters
Handling and Labour
A 203×133×25 RSJ at 3 metres weighs 75 kg. That is already awkward for two people, and at 5 metres it hits 125 kg, well beyond safe manual handling limits. Knowing the weight in advance lets you plan the right number of hands, mechanical aids, or crane hire before the steel arrives on site.
Delivery Costs and Vehicle Selection
Steel stockholders price delivery partly by weight and length. A 305×165×40 UB at 6 metres weighs 240 kg and requires a flatbed lorry with a HIAB crane. A 152×89×16 at the same length is only 96 kg and might fit on a smaller vehicle. Underestimating weight can lead to aborted delivery charges and project delays.
Crane Hire and Installation Budgeting
For beams over 100 kg or longer than 4 metres, mechanical lifting becomes necessary. Mini crawler cranes, engine hoists, or telehandlers add £200-600 per day to your budget. Knowing the beam weight during planning lets you factor crane hire into your quote from the start.
Manual Handling Limits and Legal Compliance
Under UK health and safety law, employers and self-employed builders must assess manual handling risks before moving heavy loads. The Health and Safety Executive (HSE) provides clear guidance on reducing injury risk from lifting and carrying.
Structural Load Calculations
Beam self-weight is a dead load that the structural engineer must account for in calculations. On long spans or light-load applications, the steel’s own mass can contribute 10-20% of the total bending moment and deflection. Accurate weight data ensures the specified beam has enough capacity for the actual service conditions.
How to Calculate RSJ Beam Weight
The calculation is straightforward once you know the beam’s weight per metre.
Formula:
Total Weight (kg) = Weight per Metre (kg/m) × Length (m)Example 1: A 203×133×25 beam at 4.5 metres
25 kg/m × 4.5 m = 112.5 kg
Example 2: A 254×146×37 beam at 5 metres
37 kg/m × 5 m = 185 kg
Example 3: A 305×165×46 UB at 6 metres
46 kg/m × 6 m = 276 kg
Most UK stockholders supply beams to the nearest 100 mm or as specified by your structural engineer. When estimating, always round up to be conservative on weight and cost. Manufacturing tolerances mean actual weights can vary by approximately ±2.5%, so treat calculated figures as nominal values.
RSJ Beam Weight Per Metre Chart
The chart below shows weight per metre for the most common RSJ and Universal Beam sections stocked in the UK. For a complete listing of every section size and structural property, refer to our complete RSJ size chart 2026.
| Designation | kg/m | lb/ft |
|---|---|---|
| 127×76×13 | 13.0 | 8.7 |
| 152×89×16 | 16.0 | 10.8 |
| 178×102×19 | 19.0 | 12.8 |
| 203×102×23 | 23.0 | 15.5 |
| 203×133×25 | 25.0 | 16.8 |
| 203×133×30 | 30.0 | 20.2 |
| 254×102×22 | 22.0 | 14.8 |
| 254×102×25 | 25.0 | 16.8 |
| 254×146×31 | 31.0 | 20.8 |
| 254×146×37 | 37.0 | 24.9 |
| 254×146×43 | 43.0 | 28.9 |
| 305×102×25 | 25.0 | 16.8 |
| 305×102×28 | 28.0 | 18.8 |
| 305×165×40 | 40.0 | 26.9 |
| 305×165×46 | 46.0 | 30.9 |
| 305×165×54 | 54.0 | 36.3 |
| 356×171×45 | 45.0 | 30.2 |
| 356×171×51 | 51.0 | 34.3 |
| 406×178×54 | 54.0 | 36.3 |
| 406×178×60 | 60.0 | 40.3 |
These values are based on standard British and European section tables compliant with BS EN 10025-2 and related structural steel standards. Always confirm the exact mass with your supplier when placing an order, especially for non-standard or cut-to-length sections.
Total Weight by Length
Knowing the weight per metre is useful, but what you really need on site is the total weight of the beam you have ordered. The table below shows total weights for the UK’s most popular residential RSJ sizes at standard lengths of 3 m, 4 m, 5 m, and 6 m.
| Designation | 3 m | 4 m | 5 m | 6 m |
|---|---|---|---|---|
| 203×133×25 | 75 kg | 100 kg | 125 kg | 150 kg |
| 203×133×30 | 90 kg | 120 kg | 150 kg | 180 kg |
| 254×146×31 | 93 kg | 124 kg | 155 kg | 186 kg |
| 254×146×37 | 111 kg | 148 kg | 185 kg | 222 kg |
| 305×165×40 | 120 kg | 160 kg | 200 kg | 240 kg |
| 305×165×46 | 138 kg | 184 kg | 230 kg | 276 kg |
Practical takeaways from this table:
- A 203×133×25 at 3 m is the largest beam most teams would attempt to carry manually, and even then it needs three experienced builders.
- Once you reach 4 m in any popular domestic size, total weight exceeds 90 kg and mechanical aids become strongly recommended.
- At 5 m and above, every common residential beam is over 100 kg total, meaning crane, engine hoist, or telehandler access is usually necessary for safe installation.
- The jump from a 203×133×25 to a 305×165×46 at 5 m is 105 kg versus 230 kg — more than double the weight for a similar span.
If you are unsure which beam size is right for your span and load, try our free beam size calculator to get an initial recommendation before consulting a structural engineer.
Safe Handling Guidelines
Manual Handling Limits
UK health and safety guidance recommends that men should not regularly lift more than 25 kg unaided, and women should not lift more than 16 kg. These are not legal weight limits, but they are the benchmarks courts and inspectors use when judging whether a manual handling task was reasonably safe.
For RSJ beams, the practical limits on site are usually:
- One person: Up to 25 kg for short distances on level ground.
- Two people: Up to 50 kg if the load is balanced and grip is secure.
- Three to four people: Up to 100 kg for very short moves in open spaces.
- Above 100 kg: Mechanical aids or crane hire should be used.
Team Lifting Techniques
When team lifting is unavoidable: appoint a leader who gives clear commands, lift together on the count of three, carry the beam at the same height, wear gloves and steel-toe-capped boots, plan the route in advance, and never twist while carrying.
Mechanical Aids
For beams over 100 kg, the safest options include engine hoists or chain blocks for roof openings, telehandlers for ground-floor access, mini cranes or HIAB lorries for large beams, and beam trolleys for moving steel across flat surfaces. Always conduct a risk assessment and brief all operatives on the method statement.
Delivery and Site Access: Can You Carry a 6m Beam Through a House?
The short answer is: usually no, and you should not try. The average UK terraced house is only about 4-5 metres wide internally. Even if you could angle a 6 m beam through doorways, the weight — typically 150-280 kg for common sizes — makes it physically impossible to carry safely through corridors and around corners.
Practical Delivery Options
Crane or HIAB Delivery: Most steel merchants offer HIAB lorry delivery, which uses a lorry-mounted crane to lift the beam directly over the house and lower it through a pre-prepared roof opening. This is the standard method for beams over 4 m or 100 kg.
Engine Hoist Through a Window: For smaller beams in upper-storey flats or tight terraces, an engine hoist rigged through a window can work, provided the opening is structurally sound.
Manual Carry (Rare): A short 2-3 m beam weighing under 75 kg might be carried through the house by three or four strong builders, but this is risky and should only be considered when no mechanical option exists.
Site Access Checklist
Before ordering your beam, check whether a lorry can park within crane reach, whether overhead lines or trees block the lift, whether the ground is firm enough for outriggers, and whether the beam path is clear of fragile finishes and services. Discuss access with your steel supplier before placing the order.
Weight vs Price: Does a Heavier Beam Always Cost More?
In most cases, yes — but the relationship is not as simple as you might think. Steel is priced primarily by weight, so a 30 kg/m beam will generally cost more per metre than a 25 kg/m beam of the same depth. However, market prices also depend on availability, grade, and processing costs.
When a Heavier Beam Costs Less
Occasionally, a heavier section is more economical because it is mass-produced and held in stock by every merchant. A 203×133×25 is so common that competition keeps prices keen, whereas an unusual lightweight section might carry a scarcity premium.
Strength Upgrades That Save Money
Upgrading from S275 steel to S355 allows the structural engineer to specify a lighter, smaller section for the same load capacity. The steel grade costs slightly more per kilogram, but the total weight reduction can make the overall beam cheaper.
The Real Cost of Weight
The heaviest cost associated with beam weight is often not the steel itself, but the handling and installation. A heavier beam means a bigger crane or HIAB, more rigging time, potential road closures, and higher delivery charges. It is worth asking your structural engineer whether a lighter, higher-grade solution could reduce both weight and total project cost.
Frequently Asked Questions
Q: How much does a 203×133×25 weigh?
A 203×133×25 weighs 25 kg per metre. For common lengths, that means 75 kg at 3 m, 100 kg at 4 m, 125 kg at 5 m, and 150 kg at 6 m. It is the most popular beam for standard domestic wall removals in the UK. For more details on this section, read our 203×133×25 RSJ beam guide.
Q: How heavy is a 5m RSJ beam?
It depends on the section size. A 5 m 203×133×25 weighs 125 kg, while a 5 m 305×165×46 weighs 230 kg. As a rough rule, most domestic beams at 5 m weigh between 120 kg and 230 kg, which is well above safe manual handling limits.
Q: Can two people lift a 203×133×25?
Only if it is very short. At 2 m the beam weighs 50 kg, which two strong people could potentially lift for a short distance on level ground. At 3 m it is 75 kg and awkward to balance, so three people are safer. At 4 m or longer, use mechanical aids or a larger team.
Q: What is the lightest RSJ beam for a 3m span?
For a 3 m span in a typical residential load case, a structural engineer might specify a 127×76×13 or 152×89×16, weighing 13 kg/m and 16 kg/m respectively. These are the lightest commonly stocked sections. However, the exact choice depends on load, restraint conditions, and deflection limits, so always confirm with an engineer. You can also use our beam size calculator for an initial estimate.
Q: Does the weight include the flange width?
Yes. The kg/m figure is the total mass of the entire cross-section, including both flanges and the web. The designation numbers — for example, 203×133×25 — tell you the approximate depth (203 mm), flange width (133 mm), and weight per metre (25 kg/m). The actual kg/m value is calculated from the full sectional area, not just one part of the beam.
Final Thoughts
Calculating RSJ beam weight is a simple but essential step in any steel installation project. Use the formula, refer to the chart, and always plan your handling method before the steel arrives on site. For quick reference, bookmark our RSJ beam weight per meter chart and complete size chart. If you need help choosing the right beam, our beam size calculator is a great place to start.
Disclaimer: The weights and guidance provided in this article are for general information only. Structural calculations, beam specifications, and lifting operations must be verified by a qualified chartered structural engineer and comply with current UK Building Regulations and health and safety law. Always consult a professional before ordering or installing structural steel.
