Originally Posted by allensun

You can transfer Amex Membership rewards at a ratio of 1:1.5 to Hilton directly (at increments of 1,000).

Or, you can transfer MR to Virgin Atlantic at 1:1, then transfer from Virgin Atlantic to Hilton at 1:2. This takes a lot longer and you need to transfer blocks of 5,000 from Virgin Atlantic (with a minimum of 10K miles).