How much blood is in the human body?
An adult has about 10 to 12 pints (4.5 to 5.5 liters) of blood, roughly 7% of body weight. A donation takes about one pint, less than 10% of the total.
The volume of blood in your body depends on your weight, height and sex. A common reference is that blood makes up about 7% of body weight.
Typical volume
| Person | Approximate volume |
|---|---|
| Adult man (155 lbs) | 5.0 to 5.5 liters (10.5 to 11.5 pints) |
| Adult woman (130 lbs) | 4.0 to 4.5 liters (8.5 to 9.5 pints) |
| Child (22 lbs) | about 0.8 liters |
| Newborn (7 lbs) | about 0.25 liters |
What blood is made of
- Plasma (about 55%): a yellowish fluid with proteins, hormones and nutrients
- Red blood cells (about 44%): carry oxygen
- White blood cells (under 1%): defend against infection
- Platelets (under 1%): help blood clot
What a donation takes
About one pint, a little under 10% of an adult's blood. The body compensates quickly:
- Plasma is replaced in 24 to 48 hours
- Red cells in 4 to 8 weeks
- Iron stores take longer
How much loss is dangerous?
Losing more than 30 to 40% of your blood volume becomes serious. A one pint donation is well within the margin your body can handle.
This information is general and does not replace advice from a health professional. Your eligibility is always decided at the donor screening on the day of donation. Rules change, so confirm with the American Red Cross or the blood center where you plan to donate.