By the Glass Margin Calculator

Pour size, pour buffer and total pour size

On paper a 750 mL bottle gives you five glasses of 5 oz (about 150 mL). In a real restaurant it rarely does. That is why you separate what you sell from what you plan for.

Pour size: what is on the menu

The pour size is the amount you promise the guest and set as your house standard, for example 5 oz or 6 oz. It is the size you set your price for, and it is the size the guest pays for.

Pour buffer: the extra you plan for

The pour buffer is the extra wine you reserve for every glass, on top of the pour size. It covers what you lose in daily service:

• Overpour: nobody free-pours exactly 5 oz by eye, and bartenders and servers tend to pour a little more rather than less.
• The rest in the bottle: the last ounce or so, sediment, and wine that oxidizes before you finish an open bottle.
• Tasting and spillage: a sip for the guest to try, a glass that tips over, a check for a corked bottle.

If you calculate with the exact pour size, the numbers never come back. You expect five glasses, you sell four, and the missing glass comes straight out of your margin, every single bottle.

Total pour size: what you calculate with

The total pour size is the pour size plus the pour buffer. With a 5 oz (150 mL) pour and a 30 mL (about 1 oz) buffer, the total pour size is 180 mL, and that is the number your glasses per bottle, your cost per glass and your price per glass should be based on.

Total glasses: what you really sell

The total glasses are the bottle size divided by the total pour size, rounded down. A 750 mL bottle at 180 mL gives you four glasses, not five. Price your glass on four and every bottle pays for itself, even on a busy Saturday night.

Sell the smaller size, plan for the bigger one. And there is a bonus: when the glass is a little fuller than expected, guests feel they received more than they paid for. That is a better feeling than the other way around.