Is a 90×190 cm mattress long enough for adults?

For most adults, yes. The general guideline is to choose a mattress that is at least 10 to 15 centimetres longer than the tallest person sleeping on it. A 90×190 mattress is therefore suitable for adults up to approximately 175 to 180 centimetres tall. If you are taller than that, a 90×200 or 90×210 mattress is a better fit, which may also mean replacing the bed frame.