Blood Volume Estimator
Calculate total circulating blood volume for neonates, infants, children, and adolescents. Useful for transfusion planning, blood loss estimates, and resuscitation.
Children: 70–80 mL/kg.
Optional: used to estimate red cell mass.
Results
Total blood volume
1500 mL
(≈ 1.50 L)
Red cell volume
570 mL
Based on hematocrit 38%.
Plasma volume
930 mL
Useful for estimating replacement fluids.
How to Use This Calculator
Select the correct age category
Blood volume (mL/kg) decreases with age; use the best match for your patient.
Enter accurate weight
Weight strongly influences blood volume; use recent measured weight.
Optional: Add hematocrit
Estimate red cell mass for transfusion planning or exchange transfusion calculations.
Frequently Asked Questions
Why is blood volume higher in neonates?
Neonates have higher plasma volume relative to size to support rapid growth and oxygen delivery.
How do I estimate blood loss?
Blood loss (%) = (Estimated blood loss / total blood volume) × 100. Consider transfusion if loss >15–20%.
When is hematocrit required?
Helpful for exchange transfusion, ECMO priming, or massive transfusion calculations.
Do obese children need adjustments?
Consider lean body weight factors; obesity reduces mL/kg blood volume.
Can I use this for adults?
Adult factors differ (men ~70 mL/kg, women ~65 mL/kg). Use adult-specific calculators.