Which amount are you referring to? HDHP isn't an amount per se; it's the "high deductible health plan" that qualifies you to open or contribute to an HSA.

Do you mean how high of a deductible is considered high enough to be an HDHP?

Take a look at the information below for the qualifications of a High Deductible Health Plan (HDHP).

https://ttlc.intuit.com/replies/4787500