Rookie question about 1 gal. batches

How does one account for loss of must when racking to secondary? I'm wanting to try a 1 gal. batch of green tea and ginger wine from a recipe that I recently found. I plan to use a bucket as my primary and 1 gal. glass jug as secondary. I'm wondering how much water to use at the outset. I realize I can't simply use a gallon since I will lose some amount to the tea leaves, etc. Do I get a larger amount, say 1.2 gallons for instance, up to my target OG and ferment then rack to the secondary until it's full?

Thanks in advance.

Exactly! You can even save the extra in a really tiny bottle and use that to top up your second racking.

I tend to make one gallon plus 750ml and that works out quite well. I use 375, 500, 750ml and 1.5L (depending on what I am making) for the topping up volume.

Thanks you both for the info.