Works out the whole blood volume needed to raise a recipient's PCV to a target level, based on donor PCV, recipient PCV and recipient weight.
Standard formula: (Desired PCV − Recipient PCV) ÷ Donor PCV × Blood Volume Constant × Recipient Weight.
Enter the donor's weight to check the calculated volume against a safe donation limit for that dog.
Transfusion volume (mL) = [(Desired PCV − Recipient PCV) ÷ Donor PCV] × Blood Volume Constant (mL/kg) × Recipient Weight (kg). This is the standard approach referenced across veterinary transfusion medicine sources for estimating whole blood volume from PCV values.
Canine total blood volume is commonly cited in the 80–90 mL/kg range depending on the source. The field above defaults to 90 (the most commonly cited single figure) but is fully editable to match whatever reference or hospital protocol is in use.
Commonly cited guidance allows up to 15% of a donor's total blood volume to be collected without replacement fluid therapy, or up to 20% if replacement fluids are given after donation. This calculator flags the 15% threshold as the conservative default reference point.