Free Tool · EN 1990 + EN 1993-1-1 §7.2
Beam Deflection Calculator
Calculate serviceability deflection δ and verify against EN 1990 Annex A1.4 limits (L/250, L/300, L/350, L/500). Simply supported, cantilever, fixed-fixed, propped cantilever, two-span continuous. IPE, HEA, HEB, HEM, UB, UC + custom Iy.
δ = f(E·I·L)
L/250 · L/300 · L/350 · L/500
UDL · Point load
SS · Cantilever · Fixed
IPE · HEA · HEB · HEM
UB · UC
E = 210 000 N/mm²
NL / DE / BE
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Beam Parameters
Iy in cm⁴ — leave blank to use section database value
Deflection Check
9.617 mm
δmax — maximum deflection
Iy
8,356 cm⁴
E · Iy
17,547.6 kNm²
E
210 000 N/mm²
δ = 5·w·L⁴ / (384·E·I)
EN 1990 Annex A1.4 limits
L/250
40.1% ✓
General — structural members
Allowable: 24 mm
L/300
48.1% ✓
Floors — brittle finishes
Allowable: 20 mm
L/350
56.1% ✓
Roof beams
Allowable: 17.14 mm
L/500
80.1% ✓
Visible / sensitive equipment
Allowable: 12 mm
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Related tools
Need multi-load combinations, vibration check, or composite slab deflection?
Run the full EN 1990 SLS check — multi-load combinations, vibration (EN 1990 A1.4.4), and composite slab deflection — in FrameAI Pro.
See Pro plans →Frequently asked questions
What deflection limits does EN 1990 Annex A1.4 specify?
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EN 1990 Annex A1.4 Table A1.4 gives indicative limits. The most common limits are: δ_total ≤ L/250 for general structural members, δ_variable ≤ L/300 for floors carrying brittle finishes (tiles, screed), δ_variable ≤ L/350 for roof beams, and L/500 where visible deflection or sensitive equipment is a concern. National Annexes may modify these values — the Dutch (NEN) and German (DIN) annexes retain the EN defaults.
Why is E = 210,000 N/mm² fixed for steel?
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EN 1993-1-1 §3.2.6 fixes the modulus of elasticity for structural steel at E = 210,000 N/mm² (210 GPa). This value is independent of steel grade — S235, S275, S355, S420, and S460 all have the same E. The shear modulus G = E / 2(1+ν) ≈ 81,000 N/mm² with Poisson's ratio ν = 0.3 (also fixed).
What does the L/250 limit actually mean?
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L/250 means the maximum allowable deflection is the span length divided by 250. For a 6 m span: L/250 = 6000/250 = 24 mm. For a 10 m span: L/250 = 40 mm. The limit is a serviceability criterion — it controls cracking of finishes, visual comfort, and drainage in roofs. It does NOT relate to structural strength (ULS); a beam can be far over L/250 and still be structurally safe.
Which support condition should I choose?
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Simply supported: beam rests on two supports with no moment restraint at the ends (pinned-roller). Use this for secondary beams, purlins, and most beams in braced frames. Cantilever: one end fixed, one end free — use for balconies, canopies, and cantilever overhangs. Fixed-fixed: both ends moment-connected and rotationally restrained — uncommon in practice, reduces deflection by factor of 5. Propped cantilever / two-span continuous: intermediate stiffness; deflection coefficient ≈ 1/185 compared to 1/384 for SS.
How do I check SLS for multiple load cases?
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For a rigorous EN 1990 SLS check, deflections from permanent (G), variable (Q), and imposed (Q_i) actions are summed using the characteristic, frequent, or quasi-permanent combination. This tool computes deflection for a single load — use the Pro pipeline to run EN 1990 §6.5 combination rules on extracted loads from your drawing set.