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About this tool
Pick mattress size, thickness and firmness from sleeper count, height, body weight and sleeping position.
This mattress size selector turns four facts — how many adults share the bed, the tallest sleeper's height, the heaviest sleeper's weight and the usual sleeping position — into a specific size, thickness band and firmness rating. It applies the standard bedding rules: a mattress should be at least 10 cm longer than the tallest sleeper, and each adult wants around 90 cm of width, which is a full single each. Thickness is set from body weight so the hips never bottom out on the support core.
Open Mattress Size Selector on AltFTool — it loads instantly in your browser.
Add your input to the workspace.
Adjust the options until the result looks right.
Copy or download the output and put it to work.
Adds the 10–15 cm headroom above your height instead of leaving you to guess.
Side, back, stomach and combination sleepers each start from a different point on the 1–10 scale.
Warns when the recommended size leaves under 45 cm of walkway on each side.
At least 10 cm longer than you are, and 15 cm is more comfortable. Someone 180 cm tall needs a mattress of at least 190 cm, which rules out the common 183 cm (72 in) Indian length and points to a 198 cm (78 in) size.
Around 90 cm per adult is the comfort benchmark, so 180 cm total — a king. A 152 cm queen gives each person only 76 cm, roughly the width of a child's cot, which is fine for close sleepers but tight for restless ones.
Under 60 kg, 15–20 cm is enough; 60–90 kg suits 20–25 cm; 90–110 kg is better on 25–30 cm; above 110 kg look for 30 cm or more with a high-density support core. Thicker mattresses matter because the comfort layer has to be deep enough that your hips do not reach the firm core.
Side sleepers usually do best in the medium-soft range, roughly 4–5 on a 1–10 firmness scale, because the shoulder and hip need to sink far enough for the spine to stay level. Back sleepers sit around 6–7 and stomach sleepers around 7–8. Heavier bodies compress a mattress more, so add roughly one step of firmness above 90 kg.