Checking a bed up the stairs
Here a queen box spring, 60 by 80 inches, waits at the foot of 14 steps with 80 inches of headroom. Pick your bed size in the Size menu (US sizes as Sealy lists them, UK sizes as Silentnight does) and type its thickness, then give the stairs your own figures: the width between the handrails, the headroom at its lowest point, a step’s rise and depth, and how many steps there are.
If your stairs turn, add the landing. A bed longer than the landing is wide has to swing out over the first steps of the next flight while it turns, so it must be lifted over them under the landing’s ceiling; the tool counts those steps, and only lets the bed change edge where there is headroom for its diagonal.
Why the size of the bed matters so much
A mattress is too wide to go up the stairs flat, so it goes up on an edge, and then its width or its length stands up across the flight. Measured at right angles to the stairs’ slope there is less room than the headroom: for 80 inches of headroom over 7½ by 10 inch steps, about 64 inches. The table below compares that with each bed size standing on its long edge, before the tighter ends of the flight, which the tool checks for you.
Box springs, bed bases and mattresses
The calculator treats every piece as rigid. That is exactly right for a box spring or a wooden bed base, which don’t bend at all, and on the safe side for a mattress: foam and hybrid mattresses can be curved round a landing or under a low ceiling edge. If the answer for a mattress is too close to call or a near miss, bending it may get it there; if the answer for a box spring is no, look for a split box spring (two narrower halves) or a folding base.
Bed sizes on their long edge
Carried up on its long edge, a bed's width stands up across the flight. On stairs with 7½ by 10 inch steps and 6 feet 8 inches of headroom there is about 64 in square to the slope along the flight; a bed wider than that can't be carried up that way, and the ends of the flight are tighter still.
| Size | Standing on its long edge | Along the flight |
|---|---|---|
| Twin (38 × 75 in) | 38 in | room to pass |
| Twin XL (38 × 80 in) | 38 in | room to pass |
| Full (54 × 75 in) | 54 in | room to pass |
| Queen (60 × 80 in) | 60 in | room to pass |
| King (76 × 80 in) | 76 in | too wide, if rigid |
| California king (72 × 84 in) | 72 in | too wide, if rigid |
| UK single (90 × 190 cm) | 90 cm | room to pass |
| UK small double (120 × 190 cm) | 120 cm | room to pass |
| UK double (135 × 190 cm) | 135 cm | room to pass |
| UK king (150 × 200 cm) | 150 cm | room to pass |
| UK super king (180 × 200 cm) | 180 cm | too wide, if rigid |
Sizes as the makers list them, checked September 2026: Sealy, mattress size guide (US); Silentnight, mattress sizes (UK). Headroom: International Residential Code 2021, section R311.7.2 (via UpCodes).