Beam Deflection Calculator

Calculate maximum beam deflection for point loads and uniformly distributed loads with L/360 and L/240 limit checks.

Enter Beam Parameters

Select load type and fill in values

Load Type

Beam Length (L)

Point Load (P)

Distributed Load (w)

kN/m

Load Position (distance from left)

Elastic Modulus (E)

GPa

Moment of Inertia (I)

cm⁴

Maximum Deflection

Deflection/Span

Status

L/360 (Floors)

L/240 (Roofs)

Enter beam parameters above and tap Calculate Deflection to see results.

Deflection Curve

Step-by-Step Solution

Deflection Formulas

Point Load (Center):
δ = PL³ / (48EI)

UDL:
δ = 5wL⁴ / (384EI)

Point Load (Any):
δ = Pb(L²−b²)^1.5 / (9√3×EIL)

P: Point load (N)
w: Distributed load (N/m)
L: Beam length (m)
E: Elastic modulus (Pa)
I: Moment of inertia (m⁴)

Deflection Limits

L/360: Floors with plaster ceiling

L/240: Roof members supporting ceiling

L/180: Roof members without ceiling

Related Calculators

Pro Tips

I-beams have much higher moment of inertia than rectangular sections of the same area.

Deflection is proportional to L³ for point loads and L⁴ for distributed loads.

Building codes typically require L/360 for floors and L/240 for roofs to prevent visible sagging.