Load per caster is the actual weight each individual caster needs to support — calculated as total equipment weight (plus maximum cargo) divided by the number of casters, then multiplied by a safety factor to account for uneven weight distribution.
A common rule of thumb: divide total loaded weight by the number of casters, then apply a safety factor of around 1.5 (some use higher for rough floors or uneven loading) rather than assuming perfectly even distribution across all casters.
Every multi-caster setup — the actual per-caster load is rarely a perfectly even split, especially on carts where cargo shifts or isn’t centered.
Dividing total weight evenly with no safety factor. Real-world weight distribution isn’t perfectly even, and floor irregularities add momentary extra load to individual casters — build in margin rather than sizing to the bare minimum.
How many casters do I need for X pounds?
Divide total loaded weight by the number of casters you plan to use, apply a safety factor (commonly 1.5x or higher), and confirm each caster's rating meets or exceeds that number.
Why not just divide evenly with no safety margin?
Weight distribution is rarely perfectly even, and uneven floors or off-center loads put extra momentary stress on individual casters — the safety factor covers that.