Blood Volume in Adults: Liters, Not Kiloliters

Total blood volume is measured in liters (L), not kiloliters (kL). 1 kL = 1,000 L—far exceeding human capacity.

Typical Volumes

• Adult male: ~5–6 L (70–80 mL/kg).
• Adult female: ~4–5 L (65–75 mL/kg); lower due to higher body fat percentage.
• Pregnancy: Increases 30–50% (~6–7 L) by third trimester.
• Children: ~70–80 mL/kg (e.g., 10 kg child ≈ 700–800 mL).

Clinical Relevance

• Blood donation: 450–500 mL (~10% of volume).
• Hemorrhage classification: Class I (<15%), II (15–30%), III (30–40%), IV (>40%).
• Fluid resuscitation targets based on estimated blood volume.

Kiloliters are used for municipal water storage, industrial tanks, or oil—not human physiology.