Dilution
Use this free dilution calculator to adjust your wort or must gravity by adding water — work out either how much water to add, or what your final gravity will be after adding a known amount of water.
How to use it
- Choose the calculation you need — find the water to add, or find the resulting gravity.
- Enter your current gravity reading and volume.
- Enter either your desired gravity, or your target volume after dilution.
- Read off the result instantly.
When would I need to dilute wort or must?
Common cases: your pre-boil or pre-fermentation gravity came out higher than planned (common with extract or partial mash batches), or you're topping up a concentrated must for wine or cider to reach your target batch volume. Diluting with water brings the gravity — and therefore final ABV — back in line with your recipe target.
More free home brew calculators
How to dilute wort or must to the right gravity
What it does: the first tab tells you how much water to add to bring your gravity down to a target. The second tab tells you what the gravity will be if you top up to a set volume.
How to use it: take a gravity reading of your well-mixed wort or must and measure its volume. Enter those with either your target gravity or your target volume.
The formula in plain words: the sugar in the batch stays the same when you add water, it just gets spread through more liquid. So the "gravity points" (the part after the 1, for example 55 for 1.055) multiplied by the volume stays constant. New volume = old volume × old points ÷ new points.
Worked example: you have 20 litres at 1.055 and want 1.050. 20 × 55 ÷ 50 = 22 litres, so add 2 litres of water. Or, if you top the same 20 litres up to 23 litres, the gravity becomes about 1.048.
Use boiled and cooled water, or clean bottled water, for topping up after the boil. Then work out your strength with the ABV calculator.