Event Catering Quantity Calculator

How this is calculated

THIS GIVES YOU COUNTS, NOT WEIGHTS, AND THAT IS DELIBERATE. How many grams of a given dish constitute a portion is your caterer's question - they know their menu, their plating and their kitchen. What people actually get wrong is the arithmetic in front of that: how many portions to order, how the dietary split falls out, and above all how many bottles a number of drinks turns into. That is what this calculates. ⚠️ THE PER-GUEST FIGURES ARE INPUTS, NOT RECOMMENDATIONS. Drinking rates vary enormously with the crowd, the time of day, the weather, whether people are driving and what is being served. The defaults are a common planning starting point - more in the first hour while people arrive and settle, fewer per hour afterwards - and they are a starting point rather than a finding. If you have catered for this group before, your own numbers beat anybody's convention. If you are working with a caterer or a venue, use theirs, because they will have seen the room full. ⚠️ THE BOTTLE ARITHMETIC IS WHERE THE BAR RUNS DRY. A 750 ml bottle poured into 150 ml glasses is five glasses, not six, and a generous 175 ml pour makes it four. That difference across a few hundred drinks is dozens of bottles. Both the pour and the bottle size are inputs here because both genuinely vary - and it is worth deciding the pour size deliberately rather than discovering it from whoever is behind the bar. THE SPARE ALLOWANCE IS INSURANCE, NOT A GUEST ESTIMATE. It covers a plate dropped, a guest who brings someone, a portion that comes out wrong, and the simple fact that running out is far worse than having a little left. It is applied to portions rather than to drinks, because drinks are usually bought by the case and can be returned unopened, while catered portions cannot. DIETARY REQUIREMENTS ARE A SEPARATE COUNT, NOT A PERCENTAGE TO GUESS AT. The figure this tool wants is the one from your actual RSVPs, and by the time you are ordering you should have it. The percentage field exists for planning before the replies are in. Ask on the invitation - it is the only way to get a real number, and it is also considerably cheaper than catering defensively for a share nobody counted. THIS DOES NOT MODEL STAFF, HIRE, SERVICE CHARGES OR ANYTHING ELSE ON THE QUOTE. It is a quantity tool. The number of portions and bottles is the input to a conversation about price, not a substitute for one. CHECK YOUR VENUE'S RULES BEFORE BUYING ANYTHING. Corkage, whether you may supply your own alcohol at all, and licensing hours all change the arithmetic and are all easier to discover now than after a delivery arrives.

Common questions

Why does it give portions rather than weights?

Because how many grams make a portion is your caterer's question, not a website's. They know their menu, their plating and their kitchen, and the answer differs completely between a plated three-course dinner, a buffet and a canape reception. What people actually get wrong is the arithmetic in front of that - how many portions to order once spares and dietary requirements are accounted for, and how many bottles a number of drinks turns into. Those are the numbers this produces, and they are the numbers to take into the conversation with a caterer.

Are two drinks in the first hour right?

It is a common planning starting point, not a finding, which is why it is an input rather than a constant. Real drinking rates vary enormously with the crowd, the time of day, the weather, how many people are driving, whether there is a meal in the middle and what is being served. A lunchtime wedding with a lot of drivers looks nothing like an evening reception. If you have catered for this group before, your own numbers beat any convention; if you are working with a venue or caterer, use theirs, because they have seen that room full and you have not.

Why does the pour size matter so much?

Because it decides how many bottles you buy, and the effect compounds. A 750 ml bottle at a 150 ml pour is exactly five glasses; at a generous 175 ml pour it is 4.29. Across 900 drinks that is the difference between 180 bottles and 210 - thirty bottles, on a decision nobody consciously made. It is worth agreeing the pour size with whoever is serving rather than letting it emerge, and worth knowing that free-pouring runs generous almost universally.

What should the spare allowance be?

Enough that running out is not possible, and no more. It covers a dropped plate, a guest who brings someone unexpected, a portion that comes out wrong, and ordinary miscounting. It is applied to portions rather than to drinks because the two behave differently: unopened bottles can usually be returned or kept, while catered portions are made and paid for whatever happens. That asymmetry is the whole reason the tool treats them separately - be more generous with food spares than you feel like being, and buy drinks by the case with a return arrangement.

How do I know the dietary split?

Ask on the invitation, and use the real count once the replies are in. The percentage field is for planning before you have that, not a substitute for it. Guessing is expensive in both directions - cater short and some guests get an improvised plate, cater long and you have paid for meals nobody ate. It is also worth asking about allergies separately from preferences, because they are a different kind of requirement with different consequences, and a caterer needs to know about them specifically rather than as part of a headline number.

Does this include staff, hire or service charges?

No. It is a quantity tool, and everything else on a catering quote - staffing ratios, glassware and linen hire, corkage, service charges, cake cutting, whatever else appears - is priced by the supplier and varies far too much to model. The portion and bottle counts here are the input to that conversation rather than a replacement for it. Having your own numbers before you get a quote is genuinely useful, though: it makes an unusual assumption on a quote much easier to spot and ask about.

Can I use this for a party rather than a wedding?

Yes - nothing in it is wedding-specific. The arithmetic is guests, hours, a rate per guest and a pour size, which applies just as well to a birthday, a work event or a large dinner. Weddings are simply where the numbers get big enough that getting the bottle count wrong becomes expensive and obvious. For a smaller event the same calculation still saves you the most common mistake, which is buying drinks by the bottle while thinking in glasses.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the Event Catering Quantity Calculator at https://www.bfcbrilliance.com/tools/wedding-catering-quantity-calculator.

What I entered:
- Guests (guests): ___
- Spare portions (%): ___
- Share needing a separate menu (%): ___
- Hours the bar is open (h): ___
- Drinks per guest, first hour (drinks): ___
- Drinks per guest, each hour after (drinks): ___
- Pour size (ml): ___
- Bottle size (ml): ___

What it calculated:
- Drinks to allow for: ___
- Bottles to buy: ___
- Glasses per bottle: ___
- Portions to order: ___
- Of those, separate-menu portions: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

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