None of mine are the same, good point Steve. What I did was start
noting on mine how many 750 ml bottles I got from each when I bottle.
That way I can use that to advantage when racking. Most of my 5 gallon
(US) are about 25.3 bottles, I have a few 26 and more too.

You could reverse your idea and just apply tape to full carboys and as
bottled mark them off. I would use medical cloth tape, it will never
come off or dry out if you pick the right one.

Charles,
I can't think of any chemical addition that has to be that precise
anyway. When you add acid, it's always just close to right. The
additions are ballpark, the quantity required is not necessarily
standardized since your wine is a combination of several acids.

Fining trials are usually set up in half strength increments so there
is no need to get precise there either.

Just my two cents. If you have newer carboys my rule of thumb is the
quantity to the first blister ring is 1/2 gallon, each ring after that
1 is a gallon and the top ring to the neck holds about 1/2 gallon.

Joe


> None of my carboys have the same capacity. Just variation in
> manufacturing, I guess.

> Another possibility is to mark off some masking tape and making your
> own 'measuring tapes'.
>
> Take Care,
> Steve noobie
> Oregon