Box Stacking Load (Safe Load) Calculator
Estimate how much load a corrugated box can safely bear in a stack, and how high you can stack it. Enter the box's BCT (box compression test value) and your storage conditions to get a safe load with the right safety margin applied.
Result
Indicative only. Board loses strength over time and with humidity, so a safety factor is applied. Real stacking safety depends on pallet pattern, alignment, box overhang and transit vibration, so always validate critical loads with a tested BCT. Don't have a BCT value? We measure it on the dispatch dock.
How safe stacking load is estimated
A box's BCT (Box Compression Test) is the top-load it can take before it collapses, measured fresh. But corrugated board loses strength over time and in humidity, so you never load a box to its full BCT. A safety factor is applied:
Safe load = BCT ÷ (handling × storage-time × humidity factors)
Longer storage and higher humidity both increase the factor and reduce the safe load, which is why the same box that's fine for a week in a dry warehouse can fail after months in a humid one. Dividing the safe load by the weight of one box tells you how many can stack. To learn how BCT and ECT are set, see our corrugated box guide.
Common questions
I don't know my box's BCT. Can I still use this?
You need a BCT value to get a safe load. If you don't have one, we measure BCT on our dispatch dock and can provide a batch test certificate. Once you have the number, this tool tells you the safe stacking load for your conditions.
Why does humidity reduce how high I can stack?
Corrugated board is paper, and paper absorbs moisture, which softens it and cuts its compression strength sharply. A box at 90% humidity can retain roughly half the strength it had when dry. That's why cold-chain and monsoon storage need a much larger safety margin.
Is this safe to rely on for pallet planning?
Treat it as an indicative guide. Real stacking safety also depends on pallet pattern, box alignment and overhang, and transit vibration. For critical or heavy loads, validate with a tested BCT and a proper stacking assessment, and we can help spec the box to your stack height.
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Written by LeRoy Print Packs, a printing and packaging manufacturer making cartons, corrugated boxes and labels in-house. Get a quote