Dilute Spirits to a Target ABV
Adding water does not change the alcohol inside, so original volume × original ABV = final volume × final ABV. Rearranged, it gives the water needed: 500 mL of 40% down to 25% takes 300 mL.
Your numbers
Water to add (mL)
300mL
Total
800mL
Dilution factor
1.6×
Formula
Water to add (mL) = Volume (mL) × (Starting strength ÷ Target strength − 1)
Alcohol and water contract slightly when mixed, so the real strength lands a touch above the calculation. Use a hydrometer if it must be exact.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Volume (mL) (mL)Volume in millilitres. | 500 | 0 and up |
| Starting strength (%)The strength of the drink before you dilute it. | 40 | 0 ~ 100 |
| Target strength (%)The strength you want; water can only take it down, never up. | 25 | 0.1 ~ 100 |
Step by step
Quick reference table
Results when only Volume (mL) (mL) changes and everything else stays put.
| Volume (mL) (mL) | Water to add (mL) (mL) | Total (mL) | Dilution factor (×) |
|---|---|---|---|
| 250 | 150 | 400 | 1.6 |
| 375 | 225 | 600 | 1.6 |
| 500 | 300 | 800 | 1.6 |
| 750 | 450 | 1,200 | 1.6 |
| 1,000 | 600 | 1,600 | 1.6 |
What each result means
| Result | At default values |
|---|---|
| Water to add (mL) (mL)How much water to pour in to hit the target. | 300 |
| Total (mL)Every item added together — check whether tax or tip is inside it. | 800 |
| Dilution factor (×)How many times the concentrate was expanded — 1 part to how many. | 1.6 |
Common mistakes
Alcohol and water contract slightly when mixed, so the real strength lands a touch above the calculation. Use a hydrometer if it must be exact.
Glossary
- Volume (mL)
- Volume in millilitres.
- Starting strength
- The strength of the drink before you dilute it.
- Target strength
- The strength you want; water can only take it down, never up.
- Water to add (mL)
- How much water to pour in to hit the target.
- Total
- Every item added together — check whether tax or tip is inside it.
- Dilution factor
- How many times the concentrate was expanded — 1 part to how many.
Frequently asked questions
Q. How is Dilute Spirits to a Target ABV calculated?
Water to add (mL) = Volume (mL) × (Starting strength ÷ Target strength − 1) — Adding water does not change the alcohol inside, so original volume × original ABV = final volume × final ABV. Rearranged, it gives the water needed: 500 mL of 40% down to 25% takes 300 mL.
Q. Can you walk through an example?
With Volume (mL) 500mL, Starting strength 40%, Target strength 25%, the answer is Water to add (mL) 300mL.
Q. What do I need to enter?
Enter Volume (mL), Starting strength, Target strength. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Volume (mL) (mL) moves the answer to Volume (mL) (mL) 250 → Water to add (mL) (mL) 150 and Volume (mL) (mL) 1,000 → Water to add (mL) (mL) 600. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Alcohol and water contract slightly when mixed, so the real strength lands a touch above the calculation. Use a hydrometer if it must be exact.
Related calculators
Tax rates and interest conventions differ by country and product — check your contract for real transactions.