Sealy Steeple Ortho Plus King Size Mattress
The Sealy Steeple Ortho Plus is an extra firm orthopaedic mattress, which means it's built for people who want a solid, supportive surface rather than a soft sink-in feel.
- Genuinely extra-firm feel
- Zoned support keeps lower back level
- Soft fibre top adds cosiness
£477
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Sealy Steeple Ortho Plus Mattress
More available sizes
Mattress details
Mattress
Sealy Steeple Ortho Plus Mattress
Size
Firmness
Extra Firm
Construction
Orthopaedic
Open Coil Spring
Depth (cm)
29
Layers
2
Layer Details
Comfort Layer
Soft White Fibres sit at the surface to add a touch of cosiness. They soften the first impression slightly, but this remains an extra firm mattress underneath.
Support System
PostureTech Core Support Springs with zoned PowerPack technology do the real work here. The zoning firms up support through the lumbar region, which means your lower back stays level rather than dipping.
Layer details from mattressonline.co.uk product page, September 2026.
Key benefits
- Proper space for two: At 150 x 200cm, the UK king is 15cm wider than the UK double, room you feel every time one of you turns over.
- Less partner disturbance: An extra firm surface transfers less movement than a soft one, so an early alarm on one side is less likely to wake the other.
- Extra length for taller sleepers: The UK king is 10cm longer than the UK double, which stops anyone approaching 6ft sleeping with their feet at the edge.
- Zoned support across the full width: The PostureTech springs are reinforced through the lumbar region, so both sleepers get level lower-back support rather than only the person in the middle.
- Fits most main bedrooms: We suggest a room of at least 2.7m x 2.9m, which most UK master bedrooms can manage with wardrobes in place.
This size suits you if...
You share the bed every night and a double has started to feel cramped, you or your partner needs genuinely firm orthopaedic support rather than a soft sink-in feel, or one of you is on a different schedule and you want their comings and goings to disturb you less. It also suits couples where one sleeper is tall enough to appreciate the 200cm length.
Consider another size if...
You sleep alone, or your bedroom is smaller than our suggested 2.7m x 2.9m minimum. The UK double would suit you better, and we suggest allowing at least 2.6m x 2.8m for that size.
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FAQ's
Is the Sealy Steeple Ortho Plus in a UK king good for couples?
Yes, provided you both want an extra firm feel. The 150cm width gives you 75cm each for two people sharing, and the firm surface passes on less movement than a softer mattress, so one person shifting or getting up is less likely to wake the other.
What size room do I need for the Sealy Steeple Ortho Plus UK king?
We suggest at least 2.7m x 2.9m, which leaves enough floor space to walk round the bed and open drawers. That guidance is ours rather than Sealy's. If your room is tight, measure with wardrobes and bedside tables in place before committing, as a new build master can be smaller than it looks.
Is a UK king long enough for someone over 6ft?
Usually, yes. The UK king is 200cm long, 10cm longer than the UK double, which is often the difference between comfortable and feet hanging over the end. The firm surface also helps here, since a taller sleeper's weight stays evenly supported along the full length rather than sinking at the hips.
Should I choose the UK king or the UK super king in this mattress?
The UK super king is 30cm wider than the UK king, and both are the same length, so the choice comes down to width and room size. We suggest at least 3m x 2.9m for the UK super king. If your room can take it and you want maximum personal space, size up; otherwise the UK king is the sensible pick.
How big is the Sealy Steeple Ortho Plus UK king in feet?
It measures 5ft x 6ft 6in, or 150 x 200cm. Standard UK king sheets fit it, and if you're upgrading from a double you'll need new bedding, since the UK king is 15cm wider and 10cm longer. Compare the retailers listed on this page for the current prices in this size.