Learn Russian: Какой у тебя рост и вес?

In English, we use "What is..." for almost everything. In Russian, что is strictly for identifying an object or concept (like "What is that thing?"). When asking for specific characteristics, measurements, or details out of a category (like height, color, or a phone number), you must use какой (literally "which" or "what kind of").

Why is какой in the singular form when it refers to both рост and вес?

When an adjective or a question word applies to multiple nouns joined by и (and), it usually agrees with the nearest noun. Since рост (height) is masculine singular, какой takes the masculine singular form. You don't need to make it plural just because a second noun follows.

Could I use твой instead of у тебя here?

Yes, you could say Какой твой рост и вес?, but using the у тебя construction (literally "What by you is height and weight?") is extremely natural and common in Russian. It is the standard way to talk about physical attributes, body parts, and possessions.

The pronoun тебя is in the Genitive case here. Is this the new comparison structure we are learning?