DistilCalc.com — distilcalc.com/dilution-chart — Values show water to add per litre of spirit (OIML R 22 mass balance). Verify with an alcoholmeter after dilution.
Every figure is the OIML R 22 mass balance, which accounts for the volume contraction when ethanol and water are mixed. For any strength pair not on the chart, or to work in gallons, use the ABV Dilution Calculator.
Next step: See how many bottles your diluted batch will fill.
Bottle Yield Calculator →How to Use This Chart
Find your starting ABV in the column headers across the top. Find your target ABV in the row labels on the left. The value in the cell is how much water to add per litre of spirit. Click a cell to highlight your combination and see the full calculation.
To scale to your actual batch: multiply the chart value by your volume. If you have 3 litres at 75% ABV and want to reach 40%, the chart shows 0.875 L per litre — so you add 3 × 0.875 = 2.63 L of water. For a precise result that accounts for volume contraction, use the ABV Dilution Calculator with OIML mode enabled.
Important: always verify the result with an alcoholmeter at 20°C after dilution. The chart values are based on the OIML R 22 mass balance, which corrects for ethanol-water volume contraction.
More Distilling Calculators
Working one out by hand
Take 1 litre at 60% down to 40%. The alcohol does not change, so the final volume is fixed by conservation:
The pro-rata answer stops here and says to add 500 mL. That is close, and for a rough reduction it is fine. But density does not add linearly: a litre of 60% spirit and 500 mL of water do not make 1500 mL of 40% spirit, they make slightly less, because the mixture contracts.
The OIML method balances mass instead of volume, using the density of each strength at 20 °C:
= (1500 × 0.94805 − 1000 × 0.90911) ÷ 0.99820 = 514 mL
Fourteen millilitres more than the simple answer. On a single bottle that is invisible. On a 40 litre batch it is over half a litre, and it is the difference between bottling at 40.0% and bottling at 40.4%, which in most jurisdictions is a labelling problem rather than a rounding one.
Quick reference: water per litre, and what the simple sum misses
The chart above is interactive; this table is the printable version. Bold is millilitres of water per litre of spirit by the OIML mass balance. The small figure is how much the pro-rata sum under-doses by.
| From | to 40% | to 43% | to 46% | to 50% | to 57.5% |
|---|---|---|---|---|---|
| 43% | 77+2 | — | — | — | — |
| 46% | 154+4 | 72+2 | — | — | — |
| 50% | 256+6 | 167+4 | 89+2 | — | — |
| 55% | 385+10 | 286+7 | 201+5 | 103+3 | — |
| 57.5% | 449+12 | 346+9 | 257+7 | 154+4 | — |
| 60% | 514+14 | 406+11 | 313+9 | 206+6 | 45+1 |
| 63% | 591+16 | 479+14 | 381+11 | 268+8 | 99+3 |
| 65% | 643+18 | 527+15 | 426+13 | 310+10 | 135+5 |
| 70% | 773+23 | 648+20 | 539+17 | 414+14 | 226+8 |
| 75% | 902+27 | 768+24 | 652+21 | 517+17 | 316+12 |
| 80% | 1032+32 | 889+29 | 765+26 | 622+22 | 407+16 |
| 85% | 1162+37 | 1011+34 | 879+31 | 727+27 | 498+20 |
| 90% | 1292+42 | 1131+38 | 991+35 | 830+30 | 589+24 |
| 95% | 1422+47 | 1253+43 | 1105+40 | 935+35 | 680+28 |
bold = mL of water per litre, OIML · +n = mL the pro-rata sum under-doses by
When the difference matters, and when it does not
It matters when you are bottling to a stated strength, when the gap between current and target is large, or when the batch is big enough that a percent of the water is a measurable volume.
It does not matter when you are reducing to taste, when you will re-measure with an alcoholmeter and adjust anyway, or when the drop is small. Diluting 43% to 40% differs by 2 mL per litre. Nobody needs a density table for that.
Either way, dilute in stages and confirm with a hydrometer at 20 °C before you bottle. A table is a starting point, not a substitute for a measurement.
Open the ABV Dilution Calculator for any strength pair, in litres or gallons, with both methods shown side by side.
Frequently Asked Questions
Find your starting ABV along the top column headers and your target ABV in the row labels on the left. The value at their intersection is the amount of water to add per litre of spirit. For example, to dilute from 75% down to 40% ABV, the chart shows 0.875 L — meaning you add 0.875 litres of water for every litre of spirit you have.
Multiply the chart value by your volume. If you have 4 litres at 80% ABV and want to reach 40%, the chart shows 1.000 L per litre — so you add 4 × 1.000 = 4.0 litres of water. In imperial mode the values are in fl oz per quart, so multiply by the number of quarts in your batch. Clicking any cell also shows the water needed for a 5 L example batch in the selection bar.
A dash means the target ABV is equal to or higher than the starting ABV. You cannot dilute a spirit to a higher strength by adding water — that would require redistillation or blending with a higher-proof spirit. Only combinations where the target is lower than the starting strength produce a valid water addition value.
The chart uses the OIML R 22 mass balance, which corrects for volume contraction. However, when ethanol and water mix, they contract slightly in volume (typically 1–3%), which means the chart will leave you marginally above your target. For legally regulated bottling at an exact strength such as 40.0% or 46.0% ABV, use the ABV Dilution Calculator with OIML Precise mode, which corrects for this contraction. Always verify with a calibrated alcoholmeter at 20°C regardless of which method you use.
Each cell is calculated using the standard dilution formula: Water to add = (Starting ABV − Target ABV) ÷ Target ABV, expressed per unit volume of spirit. For example, starting at 70% and targeting 40%: (70 − 40) ÷ 40 = 0.750 L per litre. This formula assumes volumes are additive, which is a close but not exact approximation due to ethanol-water contraction.
Use soft, low-mineral water — ideally distilled, reverse osmosis, or a good-quality low-TDS bottled water. Hard tap water with high calcium or magnesium content can cause haze (chill haze) in diluted spirits, particularly in aged whisky or gin. The mineral content of the water does not meaningfully affect the ABV calculation, but it does affect the final flavour and clarity of the spirit.
For spirits above 60% ABV, add water gradually while stirring. Large single additions to high-strength spirit can cause localised heating and temporary cloudiness due to rapid ethanol-water mixing. Add in increments of 100–200 mL, stir gently, and allow the mixture to homogenise before adding more. Once you are below 60% ABV the addition can be made in one step. Always measure the final ABV with an alcoholmeter after the spirit has rested and reached 20°C.