Anyone who is healthy, at least 16 years old and weighs at least 110 pounds may donate blood every 56 days (8 weeks). If you are 16-18 years old you must weigh between 110-115 pounds depending upon your height, weight, and gender. Specific medical eligibility questions change from time-to-time. Resurrection members who have recently traveled outside the United States should check with the Community Blood Center for answers to eligibility questions.