Water to Add: 50% → 43% ABV
Standard volume method. Verify the final strength with a hydrometer before bottling.
Per 1 Litre
163mL water
Per 750 mL bottle
122mL water
Per 1 US gallon
616mL water
Final volume / litre
1163mL
water to add = volume × (current ABV − target ABV) ÷ target ABV
= 1000 × (50 − 43) ÷ 43 = 163 mL per litre
Open the interactive ABV Dilution Calculator →
= 1000 × (50 − 43) ÷ 43 = 163 mL per litre
About this dilution
50% (100 US proof) is the classic bottled-in-bond and overproof reference point, while 43% is a common premium bottling strength used by many whisky and rum brands. Bringing 50% down to 43% means adding roughly 163 mL of water for every litre of spirit, increasing the batch to about 1163 mL.
For casual reduction the standard volume method above is accurate enough. When bottling at an exact legal strength, switch to OIML Precise mode in the calculator, which corrects for the slight volume contraction that occurs when ethanol and water mix.
Verify before bottling: a calibrated alcoholmeter is the only way to confirm you have hit 43% ABV. Measure at 20°C.
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Common questions
How much water do I add to dilute 50% ABV to 43%?
Add roughly 163 mL of water to each litre of 50% spirit to reach 43% ABV. The formula is water to add = volume times (current ABV minus target ABV) divided by target ABV.
Why should I verify the result with a hydrometer?
Ethanol and water contract slightly when mixed, so the real strength can sit just under the calculated figure. Always confirm with a calibrated alcoholmeter at 20°C before bottling.
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