Vacuum Cup Lifting Capacity

This selection of a suction cup depends on various conditions (e.g. surface quality and structural stability of the workpiece, desired material, shape, size, pressure difference, G force from lifting equipment etc. ) The formula below can be used generally as a theoretical estimate based on a few known values. The lifting capacity of a vacuum cup theoretically determined at sea level by using the following formula:

C = (π x (D/2)2 x V x μ)/N
C = Lifting Capacity
D = Cup Diameter
N = Desired Safety Factor
V = Vacuum Level
π = 3.14
μ = vertical surface friction coefficient

Sizing Vacuum Cups

When sizing a vacuum cup there are three crucial factors to consider. These are vacuum level,number of cups, and the desired safety factor. Cup diameter can be determined by using the following formula:

D = 2 x (W x N/V x U x π x μ)
D = Cup Diameter
W = Weight of product
N = Safety Factor
U = Number of Cups
V = Vacuum Level (bar)
π = 3.14
μ = vertical surface friction coefficient


* Safety factor for horizontal lifting applications should be at least (2). Vertical lifting applications should have a safety factor of at least (4). A factor of safety must be greater than 2 in horizontal and 4 in vertical if cups are critical, diverse or varied, or if the workpieces are porous or rough. If the acceleration or friction coefficient are not known or cannot be determined, a higher factor of safety should be used.

Vacuum level

The air pressure (ambient pressure) depends on the elevation of the location as well as the temperature of the site. The air pressure has an effect on the vacuum. The maximum pressure difference that can be attained, has direct impact on the maximum holding force. The maximum vacuum achievable is between 20%-40% (e.g. cardboard, MDF sheets, ect.) to 60-80% (e.g. metal, plastics, etc.) of the ambient pressure.

P = Pb * (1 - 2.25577 * 10^-5 * h)^5.25588
P = air pressure
Pb = 101325 (Normal temp and pressure at sea level)
h = altitude above sea level