Using 1 ft = 30.48 cm, a 3.5 ft mattress is approximately 107 cm wide, a 5 ft mattress 152 cm, and a 6 ft mattress 183 cm. These are width conversions, not guaranteed product dimensions. Confirm the actual width, length and thickness on your mattress specification.
Compare mattress widths
| Thai size | Exact conversion | Rounded width | Common Thai label |
|---|---|---|---|
| 3.5 ft | 106.68 cm | 107 cm | Single / Twin |
| 5 ft | 152.40 cm | 152 cm | Queen |
| 6 ft | 182.88 cm | 183 cm | King |
Names such as Queen and King vary between countries. For imported mattresses and sheets, compare centimetres rather than the name alone. Mattress length is a separate measurement.
A 6 ft mattress is not the outside size of the bed
An upholstered frame adds material around the mattress. Check the outside width, overall length and headboard projection on the agreed drawing. Sofa Bed Studio makes upholstered bed bases; frame dimensions are confirmed for your design.
A 183 cm mattress plus 8 cm of frame on each side gives a 199 cm outside width. Adding 60 cm clear space on each side needs 319 cm across. This example excludes wardrobes, door swings and bedside furniture; it is not a minimum room-size rule.
Choose 3.5, 5 or 6 ft around your room
- 3.5 ft: one sleeper and more floor space for other furniture.
- 5 ft: a shared bed where room clearance matters.
- 6 ft: more width for two sleepers, with the frame and access checked first.
Mark the proposed outside size on the floor, then open doors, drawers and wardrobes. Check sockets and windows at the headboard, and measure the delivery route as well.
Order sheets for the actual mattress
For fitted sheets, send mattress width × length × thickness and any topper thickness. For joined mattresses, include their combined width and a side photo. Let the team confirm the fitted pocket depth and sewing allowance.
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