Hi. Is it "cómo esta tu dia?" or "cómo es tu dia?" Thanks.
¿Cómo es ...?
but it's probably more common to say '¿cómo va tu día? - how is your day going?
On the other hand, if you mean something like "What's your (typical) day like?" (What sorts of things do you usually do?), "Cómo es tu dia?" would be fine.