How much load can glass take?

It depends on its size, thickness, type and how long the load lasts. A 1000 × 1500 mm pane of 8 mm annealed glass supported on four edges takes 2.44 kPa of 10-minute wind as a design value; toughened, 10.6 kPa.

How do you calculate the load capacity of a glass panel?

q = f_g;d · t² / (β · b²): the design strength times the thickness squared, over the shape coefficient β and the short side squared. EN 16612 gives the design strength from the glass type and the load duration.

How much stronger is toughened glass than annealed?

For a 10-minute wind load, the design strength goes from 18.5 MPa annealed to 81.0 MPa toughened, about 4.4 times, so the same pane takes 4.4 times the load.

Why does glass take less load when the load lasts longer?

Glass weakens under sustained stress (static fatigue): EN 16612 multiplies its strength by k_mod = 0.663 · t^(−1/16), t in hours. A 10-minute load gets 0.74, a month 0.44 and 50 years 0.29.

Glass · Structural

Glass load calculator

A pane supported on four edges takes a uniform load q = f_g;d · t² / (β · b²): a 1000 × 1500 mm pane of 8 mm annealed glass takes 2.44 kPa of 10-minute wind, the same pane toughened 10.6 kPa. f_g;d is the design strength in the EN 16612 form (18.5 MPa annealed, 39.4 heat-strengthened, 81.0 toughened, for a 10-minute load), β comes from the shape of the pane and b is its short side.

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Load it takes

— kPa

Design strength

— MPa

Deflection at that load

— mm

Wind speed equivalent

— km/h

peak velocity pressure ½ρv², no factors

How the load capacity is worked out

f_g;d = k_mod · 45 / 1.8 (+ (f_b;k − 45) / 1.2 if heat-strengthened or toughened) f_b;k = 70 MPa heat-strengthened, 120 MPa toughened; k_mod = 0.663 · t^(−1/16), t in hours, ≤ 1 q = f_g;d · t² / (β · b²) b = short side, β from the ratio of the sides y = α · q · b⁴ / D D = E · t³ / 12(1 − ν²), E = 70 GPa, ν = 0.23

For the 8 mm annealed pane under 10-minute wind: k_mod = 0.742, so f_g;d = 0.742 × 45 / 1.8 = 18.54 MPa. The ratio of the sides is 1.5, β = 0.4872: q = 18.54 × 8² / (0.4872 × 1000²) = 0.00244 N/mm², 2.44 kPa. It is the same arithmetic as the thickness under wind load check, turned round.

Load capacity of a 1000 × 1500 mm pane, 10-minute wind (kPa)

Thickness	Annealed	Heat-strengthened	Toughened
4 mm	0.61	1.29	2.66
5 mm	0.95	2.02	4.16
6 mm	1.37	2.91	5.99
8 mm	2.44	5.17	10.65
10 mm	3.81	8.08	16.63
12 mm	5.48	11.64	23.95

Four edges simply supported, uniform load, linear plate theory, nominal thickness. These are design values with the partial factors already in; they are not breaking loads.

What this page does not do

It does not check deflection limits. It shows the deflection at the load it finds; when that passes about half the thickness, linear theory is on the safe side for the stress but exaggerates the deflection (see the deflection calculator).
It does not handle laminated or insulating glass, point fixings or a free edge. Laminated and double glazing go through the wind load page; point-fixed glass needs a structural program.
It does not replace the national annex. Partial factors and k_sp vary by country and by product; this uses γ_M;A 1.8, γ_M;v 1.2 and k_sp 1.0 (float).

Questions people ask

How much load can glass take?: It depends on its size, thickness, type and how long the load lasts. A 1000 × 1500 mm pane of 8 mm annealed glass supported on four edges takes 2.44 kPa of 10-minute wind as a design value; toughened, 10.6 kPa.
How do you calculate the load capacity of a glass panel?: q = f_g;d · t² / (β · b²): the design strength times the thickness squared, over the shape coefficient β and the short side squared. EN 16612 gives the design strength from the glass type and the load duration.
How much stronger is toughened glass than annealed?: For a 10-minute wind load, the design strength goes from 18.5 MPa annealed to 81.0 MPa toughened, about 4.4 times, so the same pane takes 4.4 times the load.
Why does glass take less load when the load lasts longer?: Glass weakens under sustained stress (static fatigue): EN 16612 multiplies its strength by k_mod = 0.663 · t^(−1/16), t in hours. A 10-minute load gets 0.74, a month 0.44 and 50 years 0.29.