Short answer: a normal wooden bed frame holds 150–300 kg of static load, which covers two adults plus a mattress with room to spare. The number that actually breaks frames is dynamic load — the 2–3× multiplier from sitting down hard, rolling over, or kids using the bed as a trampoline. Slat spacing matters more than the frame rating: keep slats no more than 7 cm apart and add a centre rail leg on anything 140 cm wide or more.
Shop the pieces in this guide
Bed frame ratings are quoted like car horsepower and understood about as well. Here is what the numbers mean when a 90 kg adult flops onto the mattress after a long day.
Static vs dynamic: the 3× rule
Static load is weight at rest. Dynamic load is weight in motion, and it is roughly two to three times the static figure for a normal sit-down and up to four times for a jump. A 100 kg person sitting down heavily puts about 250 kg through the rail joints for a fraction of a second. Do that twice a day for five years and you have 3,650 impact events — this is why joints loosen before timber snaps.
Load capacity by frame type
| Frame type | Typical static rating | Weak point | Expected life |
|---|---|---|---|
| Solid pine slatted frame | 150–200 kg | Slat ends, screw holes | 8–12 years |
| Solid hardwood (oak, beech) | 250–300 kg | Centre rail joinery | 15–20 years |
| Steel frame with mesh base | 250–350 kg | Welds, floor glides | 12–18 years |
| MDF or particle board | 120–180 kg | Every screw hole in humid air | 4–7 years |
| Platform bed with 5 slats | 100–150 kg | Slat span, no centre support | 3–6 years |
Slat spacing: the 7 cm rule
Slats spread the load. At 7 cm spacing, a 20 kg mattress is supported across 90% of its base and the slats see modest bending. At 12 cm spacing, the mattress sags between them, the foam compresses unevenly, and the slats take point loads. If you can fit your hand sideways between two slats, the spacing is too wide for a foam mattress — pocket-spring mattresses tolerate 10 cm, memory foam wants 7 cm or less.
Centre support: the missing leg
Any bed 140 cm wide or wider needs a centre rail with at least one leg to the floor, ideally two on a 180 cm bed. Without it, the middle of the frame spans 140–180 cm unsupported, and that span is where every frame eventually bows. If your bed has a centre rail but the leg hovers 3 mm above the carpet, that 3 mm becomes a 10 mm sag within two years.
Signs the frame is already tired
- Squeaks that appear at 2 a.m. Loose joints, not ghosts. Re-tighten and add a nylon washer.
- A dip you can feel in the middle. Slats have taken a permanent set; replace the middle two.
- Corner joints that move when you push. The bolt holes have ovalised. Glue and dowel, or replace.
- Creaking when you sit on the edge. Rail-to-post connection is the first thing to go on cheap frames.
If you need more than 300 kg
Look for a steel frame rated at 350 kg+, a 12-slat base at 6 cm spacing, and two centre legs. Avoid storage beds with lift-up mechanisms for heavy use — the gas struts are rated for the mattress, not for people sitting on the lifted platform. And put the bed on a hard floor or a thin rug; a thick pile carpet lets the legs sink unevenly and loads the joints.
Keep reading
More dimension guides are in the collection, and the full index is on the furnolio journal.
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