Alligation Calculator
Calculate mixing ratios and volumes for combining solutions of different concentrations
Calculate Alligation Ratio
Pharmaceutical Solutions
Laboratory Solutions
Concentration of the stronger solution
Concentration of the weaker solution
Target concentration for the mixture
Alligation Results
Enter concentrations to calculate alligation ratio
Example Calculation
Pharmacy Example: Zinc Oxide Ointment
Problem: In what proportion should a pharmacist mix 20% and 5% zinc oxide ointments to prepare a 10% zinc oxide ointment?
Given: Higher = 20%, Lower = 5%, Required = 10%
Solution Steps
1. Calculate H: Required - Lower = 10 - 5 = 5
2. Calculate L: Higher - Required = 20 - 10 = 10
3. Ratio H:L = 5:10 = 1:2 (simplified)
Answer: Mix 1 part of 20% ointment with 2 parts of 5% ointment
Alligation Method Steps
Identify Concentrations
Higher, lower, and required
All must use same units
Calculate Differences
H = Required - Lower
L = Higher - Required
Form Ratio
H:L ratio
Simplify to lowest terms
Mix Solutions
Follow calculated ratio
Mix thoroughly
Common Applications
Pharmacy
Ointments, solutions, preparations
Laboratory
Buffer preparation, reagents
Manufacturing
Chemical processing, quality control
Food & Beverage
Alcohol content, flavor mixing
Calculation Tips
All concentrations must use the same units
Required concentration must be between higher and lower
Alligation is different from dilution
Always double-check ratio simplification
Understanding Alligation
What is Alligation?
Alligation is a mathematical method used to determine the proportions in which two or more solutions of different concentrations must be mixed to obtain a solution of a desired intermediate concentration. It's widely used in pharmacy, chemistry, and manufacturing.
Alligation Formula
H = Required - Lower
L = Higher - Required
Ratio = H:L
Key Principles
- •The required concentration must be between the higher and lower concentrations
- •All concentrations must be expressed in the same units
- •The ratio represents parts by volume or weight
Alligation vs Dilution
Alligation
Mixing two different concentrations
Results in intermediate concentration
Dilution
Adding solvent to reduce concentration
Always results in lower concentration
Volume Calculations
V_higher = H/(H+L) × V_total
V_lower = L/(H+L) × V_total
Where V_total is the desired final volume
Note: Always verify your calculations by checking that the final concentration equals the weighted average of the mixed concentrations.