Plasma Volume Calculator
The plasma volume calculator finds the blood plasma volume using the patient's hematocrit (Hct) and weight. If you are curious about what is the volume of plasma or how it's estimated, read on!
Please note that this is a calculator of blood plasma for adults. It doesn't estimate plasma volume for children.
What is the volume of plasma in a healthy person?
Plasma is a liquid that makes up around 55% of our blood volume. In preparation for the process of donating blood or in a laboratory blood test called hematocrit, blood plasma is separated by centrifugation from the formed elements of blood. They constitute the other 45%, most of which are red blood cells.
The components of blood plasma volume are:
- Water (up to 95% by volume);
- Dissolved proteins (6–8%) (serum albumins, globulins, and fibrinogen – including coagulation factors);
- Clotting factors (we refer to plasma as serum when it is without clotting factors);
- Electrolytes (Na+, Ca2+, Mg2+, HCO3−, Cl−, etc.);
- Hormones; and
- Carbon dioxide (plasma is the main medium of transportation of excretory products) and oxygen.
How does the blood plasma volume calculator work?
To calculate blood plasma volume (PV), you need the values of hematocrit (Hct) and total blood volume (TBV):
PV = TBV × (1 - Hct)
The plasma volume calculation is usually performed on the assumption that the patient's total blood volume (TBV) is 70 mL per kg body weight for males and 65 mL per kg body weight for females.
In our blood volume calculator, we use far more complicated methods of estimating TBV. You can calculate blood plasma volume more accurately using these methods using