The short answer: most top bunks are rated between 150 and 250 pounds and most bottom bunks between 200 and 450, but the number matters less than what it means. It is a static, evenly distributed load, measured under test conditions for a few minutes, and it includes the mattress and bedding. A twin mattress alone is 40 to 50 pounds, so a 200 pound top bunk has perhaps 150 pounds left for a person. And a person cannot spread their weight the way a test rig does, which is why one manufacturer whose beds are certified to 400 pounds still recommends a 200 pound maximum for the top bunk. Find the label on the bed itself, not the product page.
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