How do i figure proof liters for vinegar?

To determine the proof of vinegar, you first need to know its acetic acid concentration, usually expressed as a percentage. Vinegar typically contains 4-8% acetic acid by volume. Since proof is calculated as twice the alcohol by volume (ABV), you can use the acetic acid percentage to find the proof by multiplying the acid concentration by 2. For example, if your vinegar is 5% acetic acid, its proof would be 10.