Blood Volume & Blood Loss in Adults, Children, Babies — Reference Guide

? Blood Volume & Blood Loss Guide

Understand blood volume, loss classifications, and first aid priorities

? Estimated Total Blood Volume

Group Estimated Blood Volume Notes
? Adult Male 4,100–4,700 mL ~70 mL/kg body weight
? Adult Female 3,300–3,800 mL Slightly lower than males
? Child 1,200–1,500 mL Depends on age/size (80 mL/kg)
? Infant 300–400 mL Approx. 80–90 mL/kg body weight

? Blood Loss Classifications (Adults)

Class Blood Loss % of Volume Signs and Symptoms
Class I < 750 mL < 15% Usually no symptoms
Class II 750–1,500 mL 15–30% Fast heart rate, pale skin, anxiety
Class III 1,500–2,000 mL 30–40% Low blood pressure, confusion, rapid breathing
Class IV > 2,000 mL > 40% Severe shock, unconsciousness, death risk

? Critical Blood Loss Thresholds

Group Life-Threatening Blood Loss First Aid Action
? Adults > 1,500 mL (30%+) Lay flat, control bleeding, call 999
? Children > 500 mL

? First Aid Priorities for Major Bleeds

  1. Apply direct pressure to the wound.
  2. Call 999 – Always treat serious bleeding as an emergency.
  3. Lay the casualty down and elevate legs if no spinal injury.
  4. Use dressings or a tourniquet if trained and appropriate.
  5. Monitor for shock: pale, cold, rapid pulse, confusion.

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