How much weight can bed risers safely hold?

It varies widely by design. Adjustable plastic risers in this roundup are typically rated around 1,300 lbs per set, while oversized heavy-duty blocks claim 4,000 to 6,500 lbs. Remember that stated capacities are per set and depend on even weight distribution across all four legs, so for a loaded bed plus occupants, picking a riser with substantial headroom over your actual load is the safer bet.