The short answer: at the official ratio, the same volume of juice as sparkling wine. One 750 ml bottle of prosecco wants 750 ml of orange juice, and together they make about ten mimosas.
The official build
The International Bartenders Association specifies 75 ml prosecco + 75 ml orange juice — equal parts, 150 ml in the glass. That is the only figure here with any official standing; there is no legally fixed mimosa ratio, and Wikipedia says outright that the ratio varies.
In practice bars pour anywhere from 1:1 to 3:1 in favour of the bubbly. More wine means more mimosas per bottle and less juice — which is exactly the trade-off you are making when you pick a ratio.
Juice per bottle, by ratio
| Ratio (wine : juice) | Juice per 750 ml bottle | Mimosas per bottle |
|---|---|---|
| 1 : 1 (official) | 750 ml / 25.4 oz | 10 |
| 2 : 1 | 375 ml / 12.7 oz | 10 |
| 3 : 1 | 250 ml / 8.5 oz | 10 |
The drink count stays at ten because the glass size is fixed at 150 ml — what changes is how much of that glass is wine. Pour a larger 6 oz glass and a bottle gives you eight instead.
The carton shortcut
A standard US 64 oz (1.89 L) carton of orange juice partners with roughly one bottle of prosecco at the official ratio and yields about ten mimosas. That is the easiest thing to remember at the shop: one carton, one bottle, ten drinks.
How much for a whole brunch
Use the standard party formula — two drinks in the first hour, one per hour after, or guests × (hours + 1). A twelve-person brunch running two hours is 36 mimosas, which at the official build is about four bottles of prosecco and four litres of juice.
Planning heuristics you will see quoted vary a lot. "One bottle per three guests" is the most commonly cited and lands close to the formula. Ignore anything suggesting one to two bottles per person — that is eight to sixteen mimosas each.
Buy brut, not extra dry
This is the part almost everyone gets backwards, because sparkling wine labelling is genuinely counter-intuitive. "Extra Dry" is sweeter than "Brut." The residual sugar scale is regulated and unambiguous:
| Label | Residual sugar |
|---|---|
| Brut Nature / Zero Dosage | 0–3 g/L |
| Brut — use this | 0–12 g/L |
| Extra Dry / Extra Sec | 12–17 g/L |
| Dry / Sec | 17–32 g/L |
| Demi-Sec | 32–50 g/L |
Orange juice brings plenty of its own sugar and acidity. Brut has just enough sweetness left to round the drink out without tipping it into syrup. Demi-Sec makes a cloying mess; Brut Nature strips out the roundness and leaves it harshly acidic.
Prosecco or champagne?
Prosecco — and the IBA recipe says so explicitly. Juice masks exactly the fine character you pay a premium for in champagne. A $20–35 brut prosecco, cava or dry sparkling wine is the right buy. Keep the champagne for drinking neat.
Never mix ahead
Sparkling wine goes flat within about twenty minutes of meeting juice. That is the entire reason the mimosa bar exists as a format: chill both separately, set them out with the juice in a jug, and let people build their own. It is also less work for you. The batching guide covers what does survive being mixed ahead.
The mimosa calculator runs your guest count, brunch length and chosen ratio into an exact bottle-and-carton shopping list.