It depends upon the type of HDHP insurance plan that you have. If you have a family coverage insurance plan under your name, you can contribute the family amount allowed. If your insurance plan is for you only, then you can only contribute the individual amount allowed.
See below for the maximum contribution information for HSAs:
For 2018, the maximum contribution to an HSA is $3,450 for an individual plan or $6,900 for a family plan. This is the combined contribution from both you and your employer.
If you're 55 or older, you're allowed to contribute up to $1,000 more for a maximum of $4,450 (individual) or $7,900 (family).
Note that there are penalties if you have an excess contribution to your HSA, unless withdrawn before filing your tax return. Also, additional tax would be owed if your distribution was used for something other than medical expenses.
Plus, see more information in the FAQ below:
