Pediatric Transfusion Calculator — pRBC Volume
Enter a child's age group, weight, current haemoglobin, and target haemoglobin to calculate the packed red blood cell (pRBC) volume needed to reach the target. The calculator also shows the dose in mL/kg and estimated infusion time at a standard rate.
Age group
kg
g/dL
g/dL
≈ 10.5 mL/kg — at 3 mL/kg/hr this takes ≈ 210 min
- 1
Haemoglobin deficit (ΔHb)
Target − Current = 10 − 7 = 3 - 2
Transfusion factor (EBV ÷ Hb_pRBC)
70 ÷ 20 = 3.5EBV varies by age group; Hb_pRBC ≈ 20 g/dL (Hct ≈ 60%). - 3
pRBC volume = weight × ΔHb × factor
20 × 3 × 3.5 = 210
How does this calculator work?
pRBC volume = Weight (kg) × ΔHb (g/dL) × (EBV/20), where EBV is 65–95 mL/kg by age and Hb_pRBC ≈ 20 g/dL. A standard 10 mL/kg dose raises Hb by approximately 2–2.5 g/dL in most children. Transfuse at 3–5 mL/kg/hr; complete within 4 hours. Confirm volumes with local guidelines and clinical status.
Formula
How this is calculated
The volume of packed red blood cells (pRBC) required to raise a child's haemoglobin from a current level to a target level is determined by three quantities: the haemoglobin deficit (target − current, in g/dL), the child's total blood volume (estimated blood volume, EBV), and the haemoglobin concentration of the transfused pRBC unit.
The formula Volume = Weight × ΔHb × (EBV / Hb_pRBC) derives from a mass-balance principle: the transfused red cell mass must equal the red cell mass deficit across the entire blood volume. EBV varies by age: premature neonates have the highest volume per kilogram (≈95 mL/kg), declining steadily to ≈65 mL/kg in adolescents as body fat increases (see Pediatric Blood Volume Calculator). Stored pRBC units have a haematocrit of approximately 55–65%, corresponding to a haemoglobin of approximately 18–22 g/dL; a midpoint of 20 g/dL is used here.
In clinical practice, a common simplification is to administer 10–15 mL/kg of pRBC and re-check haemoglobin after transfusion rather than targeting an exact rise. The standard infusion rate for haemodynamically stable patients is 3–5 mL/kg/hour (maximum total 4 hours to comply with blood bank limits on time out of storage). In patients with cardiac compromise, a slower rate of 1–2 mL/kg/hour and smaller volumes (5 mL/kg) are used with careful monitoring. All transfusion decisions should incorporate clinical status, transfusion guidelines, and local blood bank protocols — this calculator provides an estimate, not a prescription.
Frequently asked questions
Evidence-based thresholds from the TRIPICU trial (Lacroix et al., NEJM 2007) support a restrictive Hb trigger of 7 g/dL for haemodynamically stable critically ill children, targeting 8–9 g/dL post-transfusion. For neonates and patients with haemodynamic instability or severe respiratory disease, higher thresholds (8–10 g/dL or more) may apply. Always follow local institutional guidelines.
Packed red blood cells are concentrated: the plasma is largely removed, leaving red cells at a haematocrit of roughly 55–65% (Hct 60% → Hb ≈ 20 g/dL, since Hb ≈ Hct/3 in g/dL). The exact value depends on how the unit was prepared (additive solution vs. double centrifugation). Using 20 g/dL gives a close estimate for most standard pRBC units prepared with additive solution in current blood banks.
For haemodynamically stable patients, the standard rate is 3–5 mL/kg/hour, typically completing within 3–4 hours. Blood banks usually require the entire unit to infuse within 4 hours of leaving temperature-controlled storage to minimise bacterial growth risk. In patients with cardiac compromise or volume sensitivity, transfuse slower (1–2 mL/kg/hr) in smaller aliquots (5 mL/kg) with furosemide cover if needed.
Also known as
TG we-Calculate Editorial Team. (2026). Pediatric Transfusion Calculator — pRBC Volume [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/pediatric-transfusion-calculator
TG we-Calculate Editorial Team. "Pediatric Transfusion Calculator — pRBC Volume." TG we-Calculate. 2026. https://we-calculate.com/calculator/pediatric-transfusion-calculator.
TG we-Calculate Editorial Team, "Pediatric Transfusion Calculator — pRBC Volume," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/pediatric-transfusion-calculator
@misc{wecalculate_pediatric_transfusion_calculator, title = {Pediatric Transfusion Calculator — pRBC Volume}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/pediatric-transfusion-calculator}}, year = {2026}, note = {TG we-Calculate} }
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