Snow Load Calculator

• •Use the Snow Load Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
• •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
• •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
• •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.

Snow accumulation on roofs is a serious structural concern that causes an estimated $2 billion in damage annually in the United States, including roof collapses, ice dam damage, and structural deformation. Understanding the weight of snow on your roof helps you determine when snow removal is necessary and whether your roof structure is adequate for your climate zone. This calculator estimates the total snow load based on roof area, snow depth, and snow density. Snow density is the critical variable that most people underestimate: fresh powder weighs only about 0.5 pounds per square foot per inch of depth, but settled snow is 2-3 times heavier, and ice-laden wet snow can weigh nearly 10 times as much as powder. A roof that easily supports 12 inches of fresh powder may be dangerously overloaded by 12 inches of wet, packed snow.

• !Assuming all snow weighs the same, when wet packed snow can weigh 10 times more than fresh powder per inch of depth.
• !Not accounting for ice dams at the eaves, which concentrate heavy loads at the weakest point of the roof overhang.
• !Removing snow only from the easily accessible portions of the roof, leaving heavy loads on interior sections that cause uneven stress.