Blood Transfusion Calculator

Calculate packed RBC units needed from current and target hemoglobin with estimated blood volume.

Medical Disclaimer

This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.

Inputs

Patient Weight (kg)

Current Hemoglobin (g/dL)

Target Hemoglobin (g/dL)

Blood Volume Factor (mL/kg)

Tab to move between fields

Results

Units of pRBC Needed

Exact Units Calculated2.6

Estimated Blood Volume (mL)4,900

Hemoglobin Deficit (g/dL)3

Expected Post-Transfusion Hgb (g/dL)10.5

Total Transfusion Volume (mL)900

How to Use This Calculator

Enter Patient Weight (kg), Current Hemoglobin (g/dL), and Target Hemoglobin (g/dL).
Set Blood Volume Factor (mL/kg) — use 70 mL/kg for adults, 80 for children.
Review Units of pRBC Needed and Total Transfusion Volume (mL).
Check Expected Post-Transfusion Hemoglobin — each unit should raise Hgb by ~1 g/dL in adults.
Reassess Hgb after transfusion; avoid liberal transfusion strategy in stable patients.

How the result changes with Current Hemoglobin (g/dL)

Current Hemoglobin (g/dL)	Units of pRBC Needed
2	7
7	3
13	0
18	0

What each input means

Patient Weight (kg): Patient weight in kilograms.
Current Hemoglobin (g/dL): Current measured hemoglobin level.
Target Hemoglobin (g/dL): Desired post-transfusion hemoglobin level.
Blood Volume Factor (mL/kg): Adult male ~70, adult female ~65, child ~80, neonate ~85 mL/kg.

What each result means

Units of pRBC Needed: Whole units of packed red blood cells to order (rounded up).
Exact Units Calculated: Precise fractional units needed.
Estimated Blood Volume (mL): Weight × blood volume factor.
Hemoglobin Deficit (g/dL): Difference between target and current hemoglobin.
Expected Post-Transfusion Hgb (g/dL): Projected hemoglobin after transfusing the rounded number of units.
Total Transfusion Volume (mL): Approximate volume at ~300 mL per unit of pRBC.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Patient Weight (kg) = 70, Current Hemoglobin (g/dL) = 7, Target Hemoglobin (g/dL) = 10, Blood Volume Factor (mL/kg) = 70 = 4 input(s) provided
Calculate Units of pRBC Needed
Units of pRBC Needed
3 = 3
Calculate Exact Units Calculated
2.6 = 2.6
Calculate Estimated Blood Volume
Estimated Blood Volume = weight * bloodVolumeFactor
4900 = 4900