The short answer: one drink per guest per hour, plus a 20 percent buffer. A 150-guest, 4-hour wedding needs 600 drinks at the flat rate, and the buffer rounds that to 720 to actually buy. Split at the common wine-leaning mix (25 percent beer, 50 percent wine, 25 percent liquor), that’s about 72 bottles of wine, 8 cases of beer, and 9 liters of liquor. The math holds at any size: multiply guests by hours, add the buffer, then split across your drink mix.
This guide is the rule and the chart. For an exact list at your own guest count, hours, and mix, use the wedding alcohol calculator instead. It runs the same math live.
The rule, in one line
Multiply your drinking-age guest count by the number of hours the bar is open. That’s your baseline at one drink per guest per hour, the figure The Knot and Zola both use. Then add a buffer on top, since a dry bar is a worse outcome than a few unopened bottles you can return.
The flat rate is an average across the night, not a per-hour ceiling. Guests hit the bar hardest in the first hour, when everyone arrives thirsty at once, then taper off. If you know your crowd runs heavier than average, or your cocktail hour is doing double duty as the only bar window, nudge the hours or the buffer up rather than the base rate.
Per guest, per hour, with the buffer
Take a 100-guest, 4-hour wedding as the base case. That’s 100 times 4, or 400 drinks at the flat rate. Add the 20 percent buffer: 400 times 1.2 is 480 drinks to actually buy. Split across the wine-leaning default, that’s 120 beer drinks, 240 wine drinks, and 120 liquor drinks, which convert to bottles, cases, and liters using standard yields: about 5 glasses per wine bottle, 24 beers per case, and 22 cocktails per liter of spirits at a 1.5 ounce pour.
Every guest count follows the same three steps: multiply, buffer, split. The chart below does that math for seven common sizes so you don’t have to.
How much alcohol by guest count
| Guests (4 hrs) | Drinks to buy | Wine | Beer | Liquor | Bartenders |
|---|---|---|---|---|---|
| 50 | 240 | 24 bottles (2 cases) | 3 cases | 3 liters | 1 |
| 75 | 360 | 36 bottles (3 cases) | 4 cases | 5 liters | 1 |
| 100 | 480 | 48 bottles (4 cases) | 5 cases | 6 liters | 2 |
| 150 | 720 | 72 bottles (6 cases) | 8 cases | 9 liters | 2 |
| 200 | 960 | 96 bottles (8 cases) | 10 cases | 11 liters | 3 + barback |
| 250 | 1,200 | 120 bottles (10 cases) | 13 cases | 14 liters | 4 + barback |
| 300 | 1,440 | 144 bottles (12 cases) | 15 cases | 17 liters | 4 + barback |
These use the wine-leaning default of 25 percent beer, 50 percent wine, and 25 percent liquor over a 4-hour bar, with the 20 percent buffer already built in. Each guest count links to a dedicated shopping list with the full breakdown: mixers, ice, cups, a bartender tip range, and a per-guest cost estimate. Shift the mix toward beer or liquor, or change the hours, and every number on this chart moves, which is exactly what the calculator does live.
The 20 percent buffer, explained
Running dry at your own wedding is the outcome worth over-buying to avoid, and most liquor stores make that cheap: they take back unopened bottles. Because returns make over-buying low-risk, a 20 percent cushion on top of the flat-rate baseline is worth building in from the start. That’s deliberately above the 10 to 15 percent range some outside guides suggest, on the theory that a few unopened cases going back to the store beats a line at a dry bar during the reception.
If your store doesn’t accept returns, or you’re buying from a source that doesn’t take unopened stock back, trim the buffer closer to 10 percent and lean on the wine and liquor lines specifically, since those hold up best if you do end up with extra.
Why “per guest per hour” beats a flat per-person number
Some guides skip the hours entirely and hand you a flat per-person number, like “plan for 5 drinks per guest.” That works only if every wedding runs the same length, which they don’t. A 3-hour reception and a 6-hour one shouldn’t buy the same amount of alcohol for the same guest count, and the per-hour rule captures that automatically: multiply guests by however long your bar is actually open, not a guess baked into someone else’s average reception length.
It also makes it easy to model a longer night. Say you’re planning 150 guests but the reception runs 5 hours instead of 4. That’s 150 times 5, or 750 drinks at the flat rate, buffered up to 900, a meaningful jump over the 4-hour figure. Guessing off a flat per-person number would miss that difference entirely.
What the chart doesn’t include
The chart above sizes a standard open bar: beer, wine, and liquor at the wine-leaning split, with mixers, ice, and cups scaled separately on each preset page. It doesn’t include a few things that are common enough to plan for on top:
A champagne toast adds one flute per guest at a 4 ounce pour, about 6 flutes per 750ml bottle, on top of the base list. A signature cocktail batched for cocktail hour draws down spirits and mixers faster than the flat rate assumes, since nearly every guest takes one in a short window, so size it separately rather than folding it into the hourly math. And non-alcoholic drinks for kids, designated drivers, and anyone skipping the bar aren’t counted here at all; budget those as their own line.
Frequently asked questions
What is the rule for how much alcohol to buy for a wedding? Buy one drink per guest per hour, then add a 20 percent buffer so you don’t run dry. A 150-guest, 4-hour reception works out to 600 drinks, and the buffer brings that to 720.
Does the per-guest rule change for a shorter or longer reception? The rule scales directly with hours. A 3-hour bar needs three-quarters of the 4-hour figure, and a 6-hour bar needs half again as much. Multiply guests by hours first, then apply the buffer.
Should I count every guest on my list? No. Count drinking-age guests who will actually visit the bar, not your full headcount. Subtract kids and any non-drinkers you can estimate, since buying for people who won’t drink inflates the order for nothing.
Is a 20 percent buffer too much? It’s deliberately generous. Most liquor stores take back unopened bottles, which makes over-buying low-risk, so a 20 percent cushion sits at the high end of the commonly cited 10 to 15 percent range on purpose.
Get the exact list for your own numbers. Open the wedding alcohol calculator →
Every guest count, in detail:
Related guides:
- Open Bar vs. Cash Bar: who pays for the drinks, and where a cash bar actually works
- How Many Bartenders Do You Need?: the staffing ratio and a guests-to-bartenders table
- Wedding Bartender Cost Guide: what bar service runs, and how to keep it under control
Consumption rate, buffer, and serving yields verified against The Knot and Zola’s wedding bar guidance; quantities are editorial planning figures generated from those published yields, not a substitute for your own headcount and crowd.
