How It Works
This calculator works in 4 steps.
Enter the high concentration
Type the stronger solution's value.
Enter the low concentration
Type the weaker solution's value, or 0 for pure diluent.
Enter the target and batch volume
Type the target, which must fall between the 2 strengths, and the total volume.
Read the parts and volumes
The calculator returns parts high : parts low and the volume of each.
The Formula
The formula takes the parts of each solution from the differences between the target and the other solution.
P_H = C_T − C_LP_L = C_H − C_TV_H = V_T × P_H / (P_H + P_L)- C_H / C_L:
- High and low concentrations
- C_T:
- Target concentration
- V_T:
- Total batch volume
- P_H / P_L:
- Parts of each solution
For 1,000 mL of 70% from 95% ethanol and water (0%), P_H = 70 and P_L = 25. V_H = 1,000 × 70 / 95 = 736.8 mL ethanol and 263.2 mL water, before contraction.
Conversion Table
The conversion table gives alligation parts and volumes for 6 strength combinations.
| High | Low | Target | Parts (H : L) | High volume | Low volume |
|---|---|---|---|---|---|
| 70 | 20 | 50 | 30 : 20 | 300 mL | 200 mL |
| 95 | 0 | 70 | 70 : 25 | 736.8 mL | 263.2 mL |
| 10 | 2 | 5 | 3 : 5 | 37.5 mL | 62.5 mL |
| 30 | 3 | 6 | 3 : 24 | 111.1 mL | 888.9 mL |
| 50 | 10 | 25 | 15 : 25 | 75 mL | 125 mL |
| 12 | 0 | 3 | 3 : 9 | 946.2 mL | 2,839 mL |
What Is the Target Concentration Mixing Calculator?
The Target Concentration Mixing Calculator is a tool that returns the proportions of a strong and a weak solution needed to make a mixture at a target concentration in between. The calculator uses the alligation method (the mixing-cross method).
Alligation finds the parts of each solution by taking the distance from the target to the opposite strength. The weak solution can be plain water at 0%, which turns the method into a standard dilution. The calculator returns parts, fractions, and volumes for a chosen batch size.
Common Uses
There are 5 main uses of this calculator.
Pharmacy compounding
Pharmacists mix 2 ointment or solution strengths to an ordered strength.
Alcohol strength
Users blend 95% ethanol with 40% ethanol to reach 70%.
Nutrient blending
Growers mix 2 nutrient tanks to a target EC.
Cleaning stock
Facility staff blend concentrate and ready-to-use stock.
Syrup strength
Food makers hit a target Brix from 2 syrups.