Roof Snow Load Calculator — BS EN 1991-1-3
Calculate roof snow loads to BS EN 1991-1-3 using UK ground snow load zones, altitude adjustment and shape coefficients by pitch.
Metres above ordnance datum (UK NA valid 0–1500m)
Angle of roof slope
Wall-to-wall span
Length of building
How We Calculate This
This calculator applies the BS EN 1991-1-3 (Eurocode 1) method for determining snow loads on roofs in the UK.
The formula
s = \u03bc1 × Ce × sk
Where: s = roof snow load, \u03bc1 = shape coefficient, Ce = exposure coefficient, sk = ground snow load
sk = sk,0 × [1 + (A − 100) / 525] for A > 100 m; sk = sk,0 for A ≤ 100 m (UK NA to BS EN 1991-1-3:2003+A1:2015, Clause NA.2.8 / Figure NA.1, valid to A = 1500 m).
Frequently Asked Questions
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Last updated: March 2026
All calculations are estimates. Verify with your supplier.