how do you work out expressed b'milk quotas?

[Jac1973]

I've just started expressing so can have a few hours retail therapy away from the bambino. But how do you work out how much to leave for whoever's looking after the baby? Do you work it out by how much the baby weighs - is there some kind of sum you do i.e. 'x' amount of ounces of milk per pound of weight?

the kellymom has a calculator thing to help you work out your lo's needs:

Estimate the number of times that baby nurses per day (24 hours).

Then divide 25 oz by the number of nursings.
This gives you a "ballpark" figure for the amount of expressed milk your exclusively breastfed baby will need at one feeding.

Example: If baby usually nurses around 8 times per day, you can guess that baby might need around 3 ounces per feeding when mom is away. (25/8=3.1).

here is a link to the page which has more info.