How is cider ABV calculated?

The standard homebrew formula is ABV ≈ (OG − FG) × 131.25, where OG is the original gravity of the juice (plus any added sugar) and FG is the final gravity after fermentation. The difference reflects how much sugar the yeast converted to alcohol and CO₂.

What gravity is plain apple juice?

Pure apple juice usually starts around 1.045 to 1.052, which corresponds to roughly 11 to 13 Brix. That yields a cider of about 5 to 6.5 percent ABV if fermented dry, without adding any sugar.

How much does added sugar raise ABV?

Each 17 grams of sugar per litre raises gravity by about 0.007 to 0.008 and adds roughly 1 percent ABV when fully fermented. The calculator adds your sugar to the starting gravity so the final ABV reflects the boosted juice.

Why do dry ciders finish below 1.000?

Apple juice contains little unfermentable extract, so cider yeast can consume nearly all the sugar. Because alcohol is less dense than water, a fully dry cider can finish at or below 1.000, sometimes around 0.996, which increases the OG−FG difference and the ABV.

Can I enter Brix instead of gravity?

Yes. Switch the input to Brix and the tool converts it to specific gravity with the standard formula before calculating. Remember a refractometer Brix reading is only valid for the starting juice — after fermentation, alcohol distorts it, so measure FG with a hydrometer.

Cider ABV Calculator

The Cider ABV Calculator works out the alcohol content of hard cider from the starting gravity of the apple juice and the final gravity after fermentation. It supports added sugar to boost strength and handles the very dry finishes typical of cider.

How it works

Cider ABV uses the same gravity-difference formula as beer:

ABV ≈ (OG − FG) × 131.25

OG is the original gravity of the juice (plus any sugar you add) and FG is the gravity once fermentation is complete. The constant 131.25 converts the gravity drop into percent alcohol by volume.

If you enter Brix instead of gravity, the tool converts with the standard relationship:

SG = 1 + (Brix ÷ (258.6 − (Brix ÷ 258.2) × 227.1))

Adding sugar

Each 17 g of sugar per litre raises gravity by roughly 0.0078 and adds about 1% ABV when fully fermented. The calculator adds your sugar contribution to the juice’s starting gravity before computing alcohol, so you can plan a stronger cider.

Worked example

Supermarket apple juice reading 1.050 ferments out to a dry 0.998:

ABV ≈ (1.050 − 0.998) × 131.25 ≈ 6.8%

Add 34 g/L of sugar and the starting gravity rises to about 1.066, pushing the same dry finish to roughly 8.9% ABV — a much stronger cider.

Notes

Cider has little unfermentable extract, so dry ciders often finish at or below 1.000; do not be surprised by a sub-1.000 FG.
Brix is only valid for the starting juice; alcohol distorts a refractometer, so always measure final gravity with a hydrometer.
Higher ABV ciders ferment more slowly and may need a more alcohol-tolerant yeast.