In general, every 1g drop in human hemoglobin is equivalent to the body losing about 40ml of blood. Because the body’s own blood is proportional to its own weight. The weight of one’s own blood accounts for about 7%-8% of one’s own body weight. For a healthy adult, the concentration of hemoglobin in peripheral blood is 120-160g/L, while the volume of blood in the whole body is about 5000ml. Therefore, every 1g drop in hemoglobin is equivalent to a loss of about 40ml of blood. Because of this, clinically it is possible to roughly project the amount of blood loss of a patient based on the degree of decline in hemoglobin, for example, for a healthy adult, if the hemoglobin concentration drops due to blood loss, if the hemoglobin concentration reaches about 60g, then it is possible to project the amount of blood loss of the patient to be about 2500ml or so. Therefore, when transfusing blood in a clinical setting, it is possible to deduce the approximate amount of blood replacement needed based on the amount of blood loss.