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Alcohol Dilution Calculator - How to Dilute Alcohol with Water or Weak Spirit

Calculate how much water or weaker alcohol to add to dilute strong spirits. Perfect for converting 91% isopropyl to 70%, making homemade liqueurs, or adjusting vodka strength.

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Calculation Parameters

%
E.g., Rectified spirit 95%, Standard vodka 40%
%
Enter 0% for pure water
%
ml

Enter Parameters

Fill in the form on the left and click "Calculate"

How to use the alcohol dilution calculator

Our alcohol dilution calculator allows you to efficiently compute the amount of alcohol and water needed for any homemade alcohol solutions. Whether you're converting 91% isopropyl alcohol to a 70% solution or distilling your own fruity liquor, this tool will be helpful in all possible scenarios.

Remember: Check the "Show contraction volume" box to account for alcohol contraction when mixing! 🍾

Usage Steps:

  1. Choose your strong alcohol - Rectified spirit (95%), standard vodka (40%), or any other concentration
  2. Select weak alcohol or water - Enter 0% for water, or the percentage of a weaker spirit
  3. Set your target concentration - Must be between the weak and strong alcohol percentages
  4. Enter the amount of strong alcohol - How much strong alcohol you want to use
  5. Optional: Enable contraction calculation - See how much volume is lost due to molecular contraction

How to dilute alcohol?

The calculator uses the cross method for alcohol dilution:

Formula:

  • D = Target% - Weak% (parts of strong alcohol needed)
  • E = Strong% - Target% (parts of weak alcohol/water needed)
  • Water needed = (E × Strong volume) / D

Example: Diluting 91% isopropanol to 70%

If you have 100 ml of 91% isopropanol and want to make 70% solution using water (0%):

  • D = 70% - 0% = 70
  • E = 91% - 70% = 21
  • Water needed = (21 × 100 ml) / 70 = 30 ml

Result: Mix 100 ml of 91% alcohol with 30 ml of water to get 130 ml of 70% solution!

Sweetness of homemade alcohol

Want to sweeten your homemade spirits? Here are the guidelines:

Sweetener Options:

  • Sugar: 100g takes 60ml of volume
  • Honey: 100g takes 75ml of volume (30% less sweet than sugar)
  • Syrup: Similar to sugar

Sweetness Ranges (for tinctures):

  • Dry: up to 50g sugar per liter
  • Semidry: 51-120g per liter
  • Semisweet: 121-220g per liter
  • Sweet: 221-330g per liter
  • Liqueur/Crème: >331g per liter

Alcohol contraction

When you mix alcohol solutions, their volume shrinks due to alcohol molecules fitting between water molecules. This is called alcohol contraction.

Contraction Table (per 1 liter of mixture):

Alcohol Concentration Volume Lost
10%6 ml
20%15 ml
30%24 ml
40%29 ml
50%31 ml
60%31 ml
70%27 ml
80%20 ml
90%10 ml

FAQs

How do you calculate alcohol dilution?

To calculate dilution: (1) Multiply weak spirit % by strong volume, (2) Divide by strong %, (3) Subtract from strong volume.

Can I dilute 91% isopropanol alcohol to 70%?

Yes! You'll need 900 ml of water to dilute 3 liters of 91% isopropanol down to 70%.

Does sugar increase the volume of alcohol?

Yes! 100g of sugar adds 60ml of volume, while 100g of honey adds 75ml.

Calculation History

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