What is the difference between an 80x200 and an 80x210 cm mattress?

An 80x210 cm mattress is 10 cm longer than the standard 80x200. The recommended rule is that a mattress should be at least 20 cm longer than the sleeper, which means the 210 cm length is the right choice for anyone taller than 185 to 190 cm. For sleepers up to around 180 cm, the 80x200 is sufficient; above that, the extra 10 cm prevents feet from reaching the edge and improves overall sleeping posture.