Distribution Coefficient Calculator

The Distribution Coefficient Calculator measures how a compound partitions between an organic solvent and water — a critical value in chemistry, pharmacology, and environmental science for predicting a substance's behavior across different phases. Enter the concentration in organic phase, concentration in aqueous phase, pH value, and temperature, then select your calculation type (LogD, LogP, or Kd) to get the distribution coefficient along with the log value and partition ratio.

mol/L

Concentration of compound in the organic phase

mol/L

Concentration of compound in the aqueous phase

pH of the aqueous phase

°C

Temperature of the system

Type of coefficient to calculate

Results

Distribution Coefficient

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Log Value

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Partition Ratio

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Frequently Asked Questions

What is the distribution coefficient?

The distribution coefficient (LogD) is the ratio of concentrations of a compound between two phases at equilibrium, typically octanol-water, and accounts for all species of the compound at a given pH.

How are LogD values calculated?

LogD is calculated as the logarithm (base 10) of the ratio of total concentration in the organic phase to total concentration in the aqueous phase at a specific pH.

What is the difference between LogP and LogD?

LogP is the partition coefficient of the neutral form only, while LogD is the distribution coefficient that accounts for all ionized and neutral species at a given pH.

How does pH affect distribution coefficient?

pH significantly affects LogD for ionizable compounds. As pH changes, the ionization state changes, which affects the compound's affinity for aqueous versus organic phases.

How are LogD values used in drug discovery?

LogD values predict drug absorption, distribution, and permeability. Values between 1-3 are typically optimal for oral bioavailability and membrane permeation.

What is a good LogD value for pharmaceuticals?

For oral drugs, LogD values between 1-3 are generally preferred. Values below 0 may indicate poor membrane permeability, while values above 5 may cause poor solubility.