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Alcohol Dilution For Pharmacy Calculator

Work out alcohol dilution for pharmacy instantly with clear inputs, formula shown and shareable results.

About Alcohol Dilution For Pharmacy Calculator

Applies the dilution equation to alcohol strengths and notes that volume contraction on mixing means the preparation should be made up to volume.

Formula

Alcohol dilution

V1 = desired strength x final volume / stock strength; nominal water = final volume - V1

Worked example

With the default values below, Alcohol Dilution For Pharmacy Calculator returns Stock alcohol required of 368.42. Change any input above and every figure here is recalculated in your browser.

Inputs used

Stock alcohol strengthaccepts 10–100
95
Desired strengthaccepts 5–99
70
Final volume requiredaccepts 1–10,000 mL
500 mL

Results

Stock alcohol required
368.42 mL
Nominal water to add
131.58 mL
Dilution factor
1.357
Practical note
Alcohol and water contract on mixing, so make up to the final volume rather than adding the calculated water separately

Step by step

  1. 1Values used
  2. 2Alcohol dilution
  3. 3Stock alcohol required= 368.42 mL
  4. 4Nominal water to add= 131.58 mL
  5. 5Dilution factor= 1.357
  6. 6Practical note= Alcohol and water contract on mixing, so make up to the final volume rather than adding the calculated water separately

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

How much contraction occurs?

Mixing equal volumes of ethanol and water loses about 3 to 4% of the combined volume.

Why is 70% used for disinfection?

Water is needed for protein denaturation, so 70% ethanol kills more effectively than absolute alcohol.

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