Pediatric Blood Volume Calculator — EBV by Age Group
Select the child's age group and enter body weight to estimate total blood volume (EBV). The result uses established age-specific mL/kg values and also shows the 10% and 20% blood-loss thresholds used in perioperative and emergency planning.
Age group
kg
Range 1,300–1,500 mL (65–75 mL/kg)
- 1
Reference factor for age group
70 mL/kgNeonates have little adipose tissue, giving a higher volume per kg. - 2
Estimated Blood Volume (EBV)
20 kg × 70 mL/kg = 1,400
How does this calculator work?
EBV (mL) = Weight (kg) × age-specific factor: premature neonates ≈95, term neonates ≈85, infants ≈75, children ≈70, adolescents ≈65 mL/kg. Blood volume per kg decreases from birth to adulthood as body fat increases. EBV drives maximum allowable blood loss, transfusion volume, and resuscitation dosing calculations.
Formula
How this is calculated
Blood volume per kilogram is inversely related to body-fat percentage: neonates have very little fat and a proportionally larger circulating volume, while adolescents approach adult values. The commonly cited reference values — 95 mL/kg for premature neonates, 85 for term neonates, 75 for infants, 70 for children 1–12 years, and 65 for adolescents — are population means derived from landmark studies and are reproduced in Nelson's Textbook of Pediatrics and the PALS Provider Manual.
Estimated blood volume (EBV) is the foundational number for three key calculations in paediatric anaesthesia and critical care. First, the maximum allowable blood loss (MABL) before transfusion: MABL = EBV × (starting Hb − transfusion trigger Hb) ÷ average Hb. Second, the packed red blood cell transfusion volume: Volume (mL) = Weight × (target Hb − current Hb) × 3–4 (see the Pediatric Transfusion Calculator). Third, emergency fluid resuscitation is typically dosed as 10–20 mL/kg of isotonic crystalloid.
In significantly obese children, using actual body weight overestimates EBV — adipose tissue is relatively hypovascular. Apply the 50th-percentile weight for the child's height as a lean weight estimate instead. The 10% and 20% loss thresholds shown in the calculator are rough landmarks: losses below 10% are typically compensated; losses approaching 20–25% produce tachycardia, rising lactate, and clinical signs of shock in most children.
Frequently asked questions
Neonates have very little adipose tissue, which is highly hypovascular. Almost all of their body mass is lean tissue with a rich blood supply, giving a higher volume per kg. As children gain fat through childhood and adolescence, the proportion of poorly vascularised tissue rises and mL/kg blood volume falls toward adult values.
Use lean (ideal) body weight in significantly obese children. A common approximation is the weight at the 50th weight-for-height percentile on CDC/WHO growth charts. Using actual weight would overestimate EBV and potentially lead to excessive transfusion volumes or fluid administration.
Loss of up to 10% of blood volume is generally well tolerated in healthy children; haemodynamic compensation (tachycardia, peripheral vasoconstriction) maintains perfusion. Loss exceeding 20–25% typically produces measurable haemodynamic compromise — falling BP, prolonged capillary refill — and triggers urgent intervention. These are rough guides, not absolute thresholds; clinical status always overrides numbers.
Also known as
TG we-Calculate Editorial Team. (2026). Pediatric Blood Volume Calculator — EBV by Age Group [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/pediatric-blood-volume-calculator
TG we-Calculate Editorial Team. "Pediatric Blood Volume Calculator — EBV by Age Group." TG we-Calculate. 2026. https://we-calculate.com/calculator/pediatric-blood-volume-calculator.
TG we-Calculate Editorial Team, "Pediatric Blood Volume Calculator — EBV by Age Group," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/pediatric-blood-volume-calculator
@misc{wecalculate_pediatric_blood_volume_calculator, title = {Pediatric Blood Volume Calculator — EBV by Age Group}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/pediatric-blood-volume-calculator}}, year = {2026}, note = {TG we-Calculate} }
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