Blood-to-Plasma Ratio Calculator
Calculate B/P and optional RBC partition from paired blood/plasma concentrations, or convert concentrations.
Blood/plasma distribution results
Enter values quantified in the same unit.
B/P is the paired whole-blood/plasma concentration ratio for the same compound, time, and conditions. The hematocrit-derived RBC value assumes the simple mass balance Cblood=(1−Hct)Cplasma+Hct·CRBC. Review temperature, equilibration time, concentration dependence, cell binding, hemolysis, matrix effects, recovery, and LOQ separately.
Basis: B/P = Cblood/Cplasma and hematocrit mass-balance equations reported in the PK literature.
Tool Guide
Definition
Blood-to-Plasma Ratio Calculator — Divide whole-blood concentration by plasma concentration for the same compound, time, conditions, and units to obtain B/P. With hematocrit, rearrange Cblood=(1−Hct)Cplasma+Hct·CRBC to derive RBC concentration and the RBC/plasma ratio.
Purpose
(1) Cross-check B/P from paired whole-blood and plasma measurements (2) Convert plasma and whole-blood concentrations arithmetically using a known B/P (3) Calculate hematocrit-based RBC/plasma partition (4) Prepare distribution values used in matrix selection and PK tables
How to Use
① In paired mode, enter whole-blood and plasma concentrations in the same unit. ② Optionally enter the hematocrit percentage for that sample. ③ Use conversion mode to translate concentration with a known B/P. ④ Review negative derived RBC values, time/concentration dependence, and assay quality in the source data. Do not pair concentrations from different times, subjects, or analytical methods.
Examples
Example) Whole blood=150 ng/mL, plasma=100 ng/mL, hematocrit=40% → B/P=1.5 and P/B=0.6667 → RBC concentration=[150−0.6×100]/0.4=225 ng/mL → RBC/plasma=2.25 With B/P=1.5, the simple whole-blood conversion of plasma 80 ng/mL is 120 ng/mL.