Avoiding overloaded boxes
The number printed on a box tells you what the box can hold. It doesn't tell you what you can safely carry.
Not professional advice. This guide is general information. It isn't a safety assessment, medical advice or a moving company's guarantee. If you have back problems, heavy items or stairs, get help or hire professionals.
Three different numbers
- Maker's rating: for example, 65 lb for U-Haul's small, medium and large boxes, 80 lb for the Shorty Wardrobe, and up to 40 kg for German two-wall cartons. This describes the box, not the person carrying it.
- Recommended packed weight: German sellers advise packing cartons to about 20 kg at most, even when they're rated for 40 kg (customkarton, heldenrechner).
- Lifting guidance: the Revised NIOSH Lifting Equation starts from a load constant of 23 kg (51 lb) for ideal conditions. Reaching, twisting, frequent lifting and poor grip reduce it (CDC/NIOSH, CCOHS). Moving boxes up stairs is rarely ideal.
How the planner flags weight
You set a comfortable carry limit (default 20 kg / 44 lb, an assumption). Boxes over that limit get a warning. Boxes over the maker's listed rating get an error. Weights are estimates from what you enter, and items with no weight aren't counted, so a box can be heavier than shown.
Keep boxes manageable
- Put dense items (books, tools, cans) in small boxes, and fill the gaps with light items.
- Heavy boxes go at the bottom of a stack, and boxes stack best when full to the top (A&G-heute handling tips).
- Check the bottom of reused boxes before loading them.