Last updated: August 15, 2026
Alcohol Dilution Calculator
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Quick Answer
The Alcohol Dilution Calculator uses the concentration equation C₁V₁ = C₂V₂ to determine how much water must be added to a spirit, tincture, or extract to reach a target ABV. It reports the water addition, final diluted volume, proof values, and water-to-spirit ratio in milliliters, liters, fluid ounces, or cups, making it useful for bar batching, infusion work, and culinary extract adjustments.
To dilute alcohol, multiply the starting ABV by the starting volume, divide by the target ABV to get the final volume, and subtract the starting volume to find how much water to add.
Key Takeaways
- Alcohol dilution works because the amount of pure alcohol stays constant while volume changes.
- The core formula is C1V1 = C2V2, followed by water to add = final volume minus starting volume.
- US proof is simply double the ABV, so 40% ABV equals 80 proof.
- Additive-volume math is excellent for home use, though official proofing can use density tables.
- A correct dilution can still taste different because lowering proof changes flavor perception.
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Formula
C₁ × V₁ = C₂ × V₂; water to add = V₂ − V₁
Where:
- C₁=Starting alcohol concentration(% ABV)
- V₁=Starting liquid volume(selected unit)
- C₂=Target alcohol concentration(% ABV)
- V₂=Final diluted volume(selected unit)
Worked Examples
Turn a 750 mL 40% bottle into a 20% liqueur base
A standard bottle of 40% spirit is being diluted for a lighter cordial or liqueur.
- 1Pure alcohol stays constant: 750 × 0.40 = 300 mL.
- 2Solve for final volume: 300 ÷ 0.20 = 1500 mL.
- 3Water to add = 1500 − 750 = 750 mL.
Dilute 500 mL of 95% neutral spirit to 40%
This is a common step when turning neutral grain spirit into a vodka-strength infusion base.
- 1Pure alcohol = 500 × 0.95 = 475 mL.
- 2Final volume needed = 475 ÷ 0.40 = 1187.5 mL.
- 3Water to add = 1187.5 − 500 = 687.5 mL.
Reduce 1 liter of overproof rum from 57% to 45%
A bar batch needs to come down from navy strength to classic overproof serving strength.
- 1Pure alcohol = 1 × 0.57 = 0.57 L.
- 2Final volume = 0.57 ÷ 0.45 = 1.2667 L.
- 3Water to add = 1.2667 − 1 = 0.2667 L.
Introduction
Alcohol dilution is one of the cleanest concentration problems in the kitchen and bar because the amount of pure alcohol stays constant when you add water. If you know the starting ABV, the starting volume, and the target ABV, you can solve the dilution with the classic equation C₁V₁ = C₂V₂. This calculator handles that math for spirits, tinctures, bitters bases, vanilla extracts, homemade liqueurs, and batching projects, then reports the water addition, final volume, proof equivalents, and the water-to-spirit ratio in your selected unit.
What Alcohol Dilution Means
Dilution lowers alcohol concentration by increasing the amount of water while keeping the amount of ethanol constant. If you start with 300 mL of pure alcohol inside a stronger mixture, that 300 mL is still there after dilution—it is simply spread through a larger total volume. That conservation idea is why dilution problems are reliable and easy to model with one equation.
How the C₁V₁ = C₂V₂ Formula Works
In the equation C₁V₁ = C₂V₂, concentration is the ABV written as a percentage and volume is the liquid amount before or after dilution. Solve for final volume using V₂ = (C₁ × V₁) ÷ C₂, then subtract the original volume to find the amount of water to add. This method assumes simple additive volume, which is accurate enough for routine kitchen, home bar, and extract-making work.
Proof Versus ABV
In the United States, proof is simply twice the ABV. A 40% spirit is 80 proof, 57% rum is 114 proof, and 20% liqueur is 40 proof. This calculator shows both because many recipes, bottling guides, and bartending references switch between the two systems. If you already know the proof, divide it by two before entering it as ABV.
Step-by-Step Dilution Method
Measure your starting strength, measure your starting volume, choose a target ABV lower than the original, and calculate the final volume required. Add most of the water, stir thoroughly, then top up slowly to the full amount. When precision matters—especially with very strong spirits—mix, let the liquid rest, and re-check with a calibrated instrument before bottling.
Why Real Bottled Volume Can Be Slightly Lower
Ethanol and water contract slightly when mixed because the molecules pack more tightly together than they do in separate liquids. For everyday bar and kitchen work, additive volume is close enough, but laboratory or commercial bottling work may use density tables and temperature-corrected hydrometer readings. That is why professional proofing often relies on official tables rather than mental arithmetic alone.
When This Calculator Is Most Useful
Use it for homemade liqueurs, cocktail batching, vanilla extract adjustments, bitters bases, tinctures, infusion projects, and spirit proofing. It also pairs naturally with the ABV Calculator when you are moving between fermentation results and final beverage strength, and with the Party Drink Calculator when you need to scale a diluted batch for service.
Common Alcohol Dilution Mistakes
The biggest mistake is entering a target ABV that is higher than the starting ABV, which cannot be reached by adding only water. Another is confusing proof with ABV or mixing units halfway through a recipe. It is also easy to forget that flavor changes with dilution: a bitter tincture or strong rum may taste dramatically different at a lower proof even when the arithmetic is correct.
Safety and Quality Notes
Use clean water and sanitized containers whenever the diluted liquid will be stored. If you are proofing beverage alcohol for sale or formal compliance, local regulations may require approved instruments and official temperature correction methods. For home use, the calculator gives dependable planning numbers, but label finished bottles clearly so the final strength is never ambiguous.
Quick Reference Card
Alcohol Dilution Quick Reference
Quick reference • Alcohol Dilution Calculator
C₁ × V₁ = C₂ × V₂; water to add = V₂ − V₁Valid range: Target ABV must be lower than starting ABV and above 0%
Common Values
⚠ Watch Out
- •The target ABV must always be lower than the starting ABV when only water is added.
- •Do not confuse proof with ABV—proof is twice the ABV in the US system.
- •Very high-proof liquids can change volume slightly when mixed because of contraction.
- •Use clean water and clearly relabel the final bottle with the diluted strength.
Pro Tips
- →Measure everything in one unit from start to finish to avoid compounding mistakes.
- →For strong spirits, mix and rest before making tiny top-up adjustments.
- →Keep batch notes for repeatable infusions, bitters, and house liqueurs.
- →Taste after dilution—aroma, sweetness, and bitterness often shift along with proof.
FAQs
How do I calculate how much water to add to alcohol?
Use the conservation formula C₁V₁ = C₂V₂. Multiply the starting ABV by the starting volume, divide by the target ABV to get the final volume, then subtract the original volume. The difference is the water you add.
Can I dilute 95% alcohol down to 40% with this calculator?
Yes. Enter the starting ABV as 95, the starting volume, and the target ABV as 40. The tool calculates the final diluted volume and the exact water addition needed to reach that strength.
What happens if my target ABV is higher than the starting ABV?
That is not a dilution problem, so the calculator correctly rejects it. Adding water can only lower concentration. To raise ABV you would need to blend with a stronger alcohol source or remove water by another process.
Is proof the same as ABV?
Not exactly, but in the United States proof is simply twice the ABV. An 80-proof spirit is 40% ABV. Outside the United States, labels are more likely to use ABV directly rather than proof.
Why might the bottled volume be slightly different from the arithmetic result?
Alcohol and water contract a little when mixed, so the observed final volume can be slightly lower than the simple additive calculation. For most home and culinary work that difference is small, but commercial proofing uses official density tables for tighter accuracy.
Can I use this for tinctures and extracts?
Yes. The dilution math works the same way for beverage alcohol, bitters bases, tinctures, and culinary extracts. The only extra consideration is flavor balance, since dilution changes aroma intensity as well as proof.
Should I add water all at once?
For small household batches, adding it in one measured addition is fine. For larger or more precise batches, add most of the water, mix thoroughly, rest briefly, and then top up to the final target so you can correct any measuring drift.