Cost Per Ounce: The Bottle Math Every Bar Needs

Every bar number — pour cost, drink price, variance — sits on one conversion: what an ounce of the stuff costs you. Get the bottle math down and everything downstream is arithmetic.

The sizes that matter

• 750 ml bottle = 25.4 oz
• 1 L = 33.8 oz
• 1.75 L (“handle”) = 59.2 oz
• Wine 750 ml = five 5-oz glasses (realistically 4.75 with pour drift)
• Half-barrel keg = 15.5 gal = 1,984 oz ≈ 124 pints (16 oz) — call it ~120 after foam
• Sixtel = 5.16 gal ≈ 41 pints

Cost per pour, three examples

Spirit: $24.00 750 ml → 24 ÷ 25.4 = $0.94/oz; a 1.5 oz pour costs $1.42.

Draft: $185 half-barrel → 185 ÷ 120 honest pints = $1.54/pint; at $7.00 that's a 22% pour cost.

Wine by the glass: $11.00 bottle → ÷ 4.75 = $2.32/glass; at $9 that's 26%.

Two habits that keep the math true

Cost the case, not the sticker. Your invoice price per bottle moves with deals and splits — read the invoice at the unit level and keep cost-per-ounce current, not the number from when you opened.

Account for the invisible ounces. Draft foam, the heel of the bottle, over-pours: build 3–5% loss into beer and wine costs rather than pretending every ounce sells. Pretend-math is where variance hides.

Freecost stores bottle-size units and computes per-ounce costs automatically, so a price change on the invoice reprices every cocktail that pours from that bottle.