Most kindness asks for money or time. Giving blood asks for something stranger: a small part of you. It takes about an hour and costs nothing. And according to the American Red Cross, it is something only volunteers can do, because "blood and platelets cannot be manufactured."
How much blood the country needs
The Red Cross's blood supply facts put the scale plainly. Every two seconds someone in the U.S. needs blood or platelets. Hospitals need approximately 29,000 units of red blood cells every day, along with nearly 5,000 units of platelets and 6,500 units of plasma. The average red cell transfusion is about 3 units, and a single car accident victim "can require as many as 100 units of blood."
It isn't only emergencies. Blood goes to surgeries, cancer treatment and chronic illnesses. Sickle cell disease affects 90,000 to 100,000 people in the U.S., the Red Cross notes, and many of them need transfusions throughout their lives.
Why the supply is always short
Three things keep blood banks on edge.
- Few people give. The Red Cross says "only about 3% of age-eligible people donate blood yearly," roughly 6.8 million people a year.
- It doesn't keep. According to the Red Cross's guide to what happens to donated blood, red cells are refrigerated for up to 42 days and platelets kept at room temperature for up to five. You can't stockpile a year's worth.
- The most useful types are rare. Type O is the type hospitals request most. Only 7% of people in the U.S. are type O negative, the red cells that can go to patients of any blood type, so it is "always in great demand and often in short supply."
The Red Cross isn't the only collector. It supplies about 40% of the nation's blood. Independent community blood centers in the America's Blood Centers network supply 60 percent of the U.S. blood supply. Either kind of donation helps patients near you.
What one donation does
A whole blood donation collects about a pint. Most donations are then spun in a centrifuge and separated into red cells, platelets and plasma, so different parts can go to different patients. That's why the Red Cross says "one donation can help save more than one life." Every unit is also tested for blood type and infectious diseases before it is used.
If you were turned away in the past, the rules may have changed. In May 2023 the FDA issued guidance on individual risk-based questions for donor screening, which shifts screening toward questions about each donor's own risk. The Red Cross's eligibility page now notes the "elimination of questions based on gender and sexual orientation," along with recent changes for people who spent time in Europe.
Today's act
The act: Book one donation appointment. It takes about an hour, and most of that is paperwork and a snack.
- Check the basics: for whole blood, the Red Cross says you must be in good health, at least 16 in most states, and weigh at least 110 pounds. You can give every 56 days.
- Schedule with the Red Cross or with your local community blood center. Hospitals near you rely on both.
- Type O, or a platelet donor? Ask about the donation types. Platelets can be given as often as every 7 days.
- Bring a friend. A shared appointment is easier to keep. For more ideas, see our volunteering guide.
Sources
- American Red Cross — Blood needs and blood supply
- American Red Cross — What happens to donated blood
- America's Blood Centers — U.S. Blood Donation Statistics and Public Messaging Guide (Jan. 2026)
- U.S. FDA — Recommendations for evaluating donor eligibility using individual risk-based questions (May 2023)
- American Red Cross — Eligibility requirements
- American Red Cross — Types of blood donations