Dinner: about one glass per guest per hour.
Bottles to buy
| Wine | Glasses | Buy |
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The math
A 750 ml bottle holds 5 × 150 ml glasses — the standard restaurant pour. For dinners, plan one glass per guest per hour; parties run slightly higher in hour one (the arrival glass) which the calculator includes. A toast is different: pours are 100 ml, so a bottle covers 6–7 flutes, and you only need one round — the prosecco guide covers toast maths in detail.
When you serve red and white, buy slightly more than half of each rather than exactly half — crowds are never perfectly balanced, and the calculator adds that buffer. Leftover unopened bottles keep for years; a table that wants white when you only have red remembers it for years too.
How many bottles of wine for 20 guests at dinner?
20 guests × 3 hours × 1 glass/hour = 60 glasses = 12 bottles. Split as 7 red / 7 white if serving both (the buffer makes it 14 total).
How much wine per person for a party?
Plan roughly half a bottle per wine-drinking guest for a 3–4 hour party if wine is the main drink; less if beer and cocktails share the load — the party drink calculator handles the full-bar case.
Should I buy magnums or cases?
Cases of 12 standard bottles are usually cheapest per glass and easiest to chill. Ask the shop about sale-or-return on unopened bottles — many offer it for events, which makes overbuying free.