Westpak is certified to conduct product/package integrity testing to help guarantee successful delivery of products worldwide by any means of transportation.

Westpak is accredited to ISO/IEC 17025-2005, one of the most rigorous standards available for a mechanical testing laboratory.

ASTM D4169 Vehicle Stacking / Stacked Vibration Top Load Calculator

Reference ASTM D4169-16

Top Load Formula


L =computed top load, lbf

Mf = shipping density factor, lb/ft3

J = 1lbf/lb (conversion factor)

H = max height of stack in vehicle, in

h = height of shipping unit or individual container, in

l = length of shipping unit or individual container, in

w = width of shipping unit or individual container, in

K = 1728 in3/ft3

F = combined effect factor (use 10 for ALI, 7 for ALII, 5 for ALIII)

Package Dimensions

Length (l): (inches)

Width (w): (inches)

Height (h): (inches)

Maximum Stack Height in vehicle (H): (inches)

Shipping Density (Mf):

F Factor:


Computed Top Load: pounds

Notes: 1. This formula is for Vehicle Stacking made up of mixed commodities shipped in a Less-Than-Truck-Load (LTL) or small package delivery environment.

2. Maximum Stack Height (H) is 54 inches or 108 inches per the standard.

3. Shipping Density (Mf) is almost always 10, per the standard

4. The results of the Computed Top Load formula can be used as reference however must not be used to rate the ability of shipping containers to withstand an actual top load. Such an estimate shall not be used in place of testing conditioned test samples in a controlled, repeatable, test environment with calibrated instrumentation, validated machines, and trained test operators.