What this calculator does
Get a shopping list of how much food, drink and ice to buy for your party. Hosts tend to worry about running out, then end up with trays of leftovers. A few per-guest rules of thumb get most gatherings close enough. They're adjusted for how long the party runs and who is coming. This calculator applies those rules to your guest list. It covers appetizers, main dish, sides, bread, desserts, drinks and ice, with a safety margin you choose.
Pick the kind of party: appetizers only, a buffet meal, or dessert and drinks. Enter the number of adults and young children and how long the event lasts. Then read the totals. Each total shows its per-guest amount beside it. That way you can see the assumptions and adjust for a crowd that eats more or less than most.
Where it's used
Why this math matters outside the classroom:
- Birthday parties. A parent planning for 12 adults and 8 children counts 12 + 4 = 16 portions before shopping.
- Office lunches. An office manager orders 6 oz of chicken for each of 30 people, which is 180 oz or 11.25 lb.
- Unit rates in class. Students use 2 drinks per guest per first hour to find that 15 guests need 30 drinks in that hour.
- Graduation open house. A family expecting 60 guests over 3 hours buys about 60 lb of ice at a pound per guest.
- Club fundraisers. A school club adds a 15% margin to 80 dessert servings and bakes 92.
Grade level and standards: Grades 5–6; Common Core State Standards for Mathematics 6.RP.A.3.b. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose the type of party.
- Enter adults (including teens) and young children. Children count as half a portion.
- Enter how many hours the party lasts and the extra margin you want, 10% by default.
- Use the shopping list, rounding up to package sizes. Keep in mind that drinks and ice run out faster in hot weather.
What the inputs mean
- Type of party
- Appetizers only means finger food stands in for a meal, so the amount grows with time. At a buffet meal, a lighter round of appetizers comes first. Dessert and drinks suits an afternoon reception or a gathering after dinner.
- Young children
- Young children usually eat around half an adult portion. Count teenagers as adults.
- Event length
- As the hours go by, guests keep drinking. At an appetizer-only party, they keep eating too. Main-dish amounts don't change with time.
- Extra for safety
- 10% covers most surprises. Use more for a crowd of big eaters or an open invitation. Use less if you'll happily eat the leftovers.
Formula and method
guest portions = adults + 0.5 × children amount to buy = per-guest amount × guest portions × (1 + margin ÷ 100) appetizers (appetizers only) per guest = 6 + 4 × (hours − 1) drinks per guest = 2 + 1 × (hours − 1) buffet per guest: 6 oz main, 5 oz starch, 4 oz vegetables (cooked), 1½ rolls, 1 dessert, 5 appetizers
Each line multiplies a per-guest amount by the number of guest portions and your margin. "Hours" is how long the party lasts, and "margin" is the safety extra you chose, as a percent. Things you count (pieces, rolls, drinks, servings) are rounded up to whole units. Weights are shown in pounds to one decimal place, at 16 oz per pound.
The per-guest figures are common planning habits of hosts and caterers, not measured standards. The main-dish weight is cooked and boneless. Buy more raw weight for meat that loses water as it cooks or comes on the bone.
Worked example
You're hosting a three-hour buffet dinner for 20 adults and want a 10% margin.
- Guest portions = 20 + 0.5 × 0 = 20; with the margin, 20 × 1.1 = 22.
- Main dish = 6 oz ÷ 16 × 22 = 8.25 lb cooked.
- Appetizers before the meal = 5 × 22 = 110 pieces.
- Drinks = (2 + 1 × 2) × 22 = 88 drinks; ice = 22 lb.
Result: Plan on about 8.3 lb of cooked main dish, 110 appetizer pieces, 6.9 lb of starch, 5.5 lb of vegetables, 33 rolls, 22 desserts, 88 drinks and 22 lb of ice.
Understanding the result
Treat the totals as a starting point. A crowd of teenage athletes eats more than a mid-afternoon office gathering. A hot day doubles the ice.
When you offer several choices for one course, split the total between them. Don't give each one the full amount. Expect the most familiar option to go first.
Food safety still applies. Keep hot food hot and cold food cold. Don't leave perishable food out at room temperature for more than about two hours (one hour in very hot weather).
Assumptions and limitations
- Guests are typical adult eaters, and young children eat about half as much.
- Main and side weights are cooked, ready-to-serve amounts.
- Drinks include all kinds, from water and soft drinks to alcohol.
- These are rules of thumb, not a guarantee. Appetites vary with age, time of day, weather and culture.
- It doesn't plan specific menus, dietary needs or allergies.
- It doesn't convert cooked weights to raw weights for buying, since those depend on the food.
Frequently asked questions
How many appetizers per person should I plan?
When appetizers come before a meal, about 5 pieces per guest is a common rule. When they're the whole menu, plan more and add more as the hours go on. This calculator uses 6 pieces for the first hour and 4 for each hour after.
How much meat per person for a party?
A common planning figure is about 6 oz of cooked, boneless meat per adult when there are sides. Buy more raw weight than that. Meat shrinks as it cooks, and bones add weight you can't serve.
How many drinks per guest?
A widely used rule is 2 drinks per guest in the first hour and 1 per hour after that. That counts every kind of drink. Plan more on a hot day.
How much ice do I need?
About 1 lb per guest covers drinks for most gatherings. If you're also chilling bottles and cans in coolers, buy a good deal more.
Should I count children as full guests?
Young children usually eat around half an adult portion, and that's how this calculator counts them. Teenagers often eat as much as adults or more, so count them as adults.
How this calculator is checked
Method: Per-guest planning conventions (stated in the page and table): children as half portions; appetizer and drink counts that grow with event length; cooked buffet portions of 6 oz main, 5 oz starch, 4 oz vegetables; 1 lb ice per guest; multiplied by guest portions and a user-chosen margin. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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