The UK double (135 × 190 cm) hits the sweet spot between price, bedroom space requirement and sleeping comfort. It's large enough for most couples in standard UK bedroom sizes, yet compact enough to fit in a second bedroom or allow reasonable furniture alongside. Most mattress brand pricing is quoted for double size — it's the benchmark size for comparison.

Double for couples: is it enough?#

A double gives each partner 67.5 cm of width — less than a generous single. For most couples of average build who sleep reasonably still, a double works. For couples where one or both partners is tall, heavier, or a restless sleeper, a king size (adding 15 cm of total width) is a meaningful improvement worth considering if the bedroom allows it.

Best double mattress under £400: Nectar Original#

During Nectar's regular promotions, the double Original comes in under £380 and sometimes under £350. Five layers of quality foam, a Tencel cover and the 365-night trial make it the best value double in the sub-£400 category.

Best double hybrid under £600: OTTY Original#

At double size, OTTY's hybrid comes in around £450–£550 during sales — competitive pricing for a genuine pocket-spring hybrid with a 5 cm gel-foam comfort layer.

Best all-round double: Emma Original or Simba Hybrid#

Emma and Simba are the two most trusted direct-to-consumer brands for double mattresses in the UK. Emma is better for side sleepers and those who prioritise pressure relief; Simba for back sleepers and hot sleepers. Both offer 200-night trials and 10-year guarantees at comparable price points during sales.

Should you upgrade to king?#

If your bedroom is 10′ × 12′ (304 × 366 cm) or larger and you sleep with a partner, upgrading from double to king is worth considering. The additional space (each partner gains 7.5 cm of width and 10 cm of length) consistently ranks as one of the highest-impact sleep quality improvements couples report.