• Question: How much blood is there in a human body?

    Asked by Maria Guerrero to Gemma on 15 Nov 2015.
    • Photo: Gemma Barron

      Gemma Barron answered on 15 Nov 2015:


      Hi @Maria Guerrero,
      Thank you for your interesting question. Blood is vital for our existence and the amount of blood in a human body varies, depending on age, sex, overall health and even where a person lives. For example, men tend to have more blood than women due to them being bigger in size and weight. Also, people who live at high altitudes may have up to 2 litres of extra blood compared to people living at lower altitudes. This is because the air at higher altitudes has less oxygen and people who live at these altitudes tend to need extra blood to deliver the right amount of oxygen to their lungs.
      Scientists estimate the volume of blood in a human body is approximately 7% of body weight. Thus an average adult body (weighing 150-180 pounds) will contain approximately 4.7-5.5 litres of blood whilst, the average child (weighing 80 pounds) will have approximately half the amount of blood as an adult.
      I hope that answers your question. Thanks, Gemma

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