How many levels a warehouse cage can reach depends not on the cage's height but on the load-bearing capacity of the bottom cage and the flatness of the floor. Standard folding cages are commonly stacked 3 to 4 high, heavy-duty cages 2 to 3, and light-duty turnover cages up to 5—provided every level is evenly and fully loaded.
Stacking height must also account for a safety margin. The levels marked by the manufacturer already include a margin of at least 1.1×, and in practice it is wise to discount them further by 10%: if 4 levels are marked, run 3 fully loaded in daily use to leave buffer for overload and uneven floors.
Floor conditions matter a lot. If the flatness of a concrete floor varies by more than 5mm per meter, some stacking feet hang in the air and the whole stack's weight concentrates on just a few feet, so local overload can buckle the cage. Test the flatness of epoxy floors and warehouse floors first; anything beyond 8mm/2m calls for dropping one stacking level.
Another often-overlooked factor is cargo height. When cargo inside the cage rises above the top edge of the opening, the upper cage's stacking feet cannot seat properly—it effectively sits on the cargo instead of on the feet, and the load path is completely different. Cargo must stay at least 50mm below the cage opening before stacking.
In short: 3 levels for standard cages and 2 for heavy-duty cages are the safe daily range; drop one more level when loads run high, floors are uneven, or cargo is off-center. Nanjing Tongnuo Warehouse Equipment Manufacturing Co., Ltd. recommends stacking levels based on your site conditions and cargo characteristics to avoid blind over-stacking.