A conventional US queen is usually 60 by 80 inches; a standard king is usually 76 by 80. California king is usually 72 by 84. Verify your actual mattress rather than letting a questionnaire choose the larger label.
Measure width, length and depth with any topper that stays in place. Confirm the selected variant in the basket, since retailers can reuse photos. For powered cooling, check whether the pad covers the whole bed or one sleeper and whether the required controller is included.
Split adjustable setups need explicit compatibility with separately moving mattresses. A full-width pad is not automatically suitable. Check the securing and hose instructions before ordering. Correct sizing is a specification check, not a weighted preference score.
For manufacturer-linked examples and the distinction between fabric, foam and powered systems, see our cooling bedding guide .
See Also
Turn this advice into a better bedroom setup with How a Cooling Pad May Feel: What to Check at Home, How to Choose a Cooling Mattress Pad for Summer Comfort, and Cooling Mattress Pad Water Retention and Stubborn Stains.
For the next decision on comfort, sound, temperature, or room air, continue with Cooling Mattress Pads for Sensitive Skin: Check Materials and Best Mattresses for Every Sleep Style.