People type this into search every day: catering portion calculator.
The quantity is the grams you type, times the guest count, times a buffer. It is not a nutrition target and it is not a quote from a caterer. This page follows the catering portions calculator.
Guests, times grams, times the buffer
The calculator treats the portion as an average adult serving. Children and separate diets are a second run, which Example 6 does by hand. The vegetarian share is a slice of the main, not a pile added on top.
factor = guests × (1 + buffer ÷ 100)
main kilograms = factor × main grams ÷ 1,000
side kilograms = factor × side grams ÷ 1,000
vegetarian main = main kilograms × vegetarian share ÷ 100
Buffered servings are the ceiling of the factor. The kilograms use the factor itself, not that ceiling.
On a US display, kilograms become pounds. The gram inputs stay in grams.
Fig 1
Guests into kilograms
The buffer multiplies the guest count first
Main and sides both use guests times the buffer. The vegetarian line is a share of the main, not an extra dish on top.
The 350 g and 200 g defaults are the fields as published. They are not a recommended plate. Change them to the portions you intend to serve. Drinks are a different calculator. The birthday party budget post is the money. The recipe scaler post is one ingredient, from one serving count to another. A wedding guest list is the wedding savings problem before it is a food problem.
Example 1: 45 guests, the published defaults
- guests: 45
- main food per guest: 350 g
- side food per guest: 200 g
- buffer: 12%
- vegetarian share: 20%
Factor: 45 × 1.12 = 50.4
Main: 50.4 × 350 ÷ 1,000 = 17.64 kg, displayed as 38.9 lb
Sides: 50.4 × 200 ÷ 1,000 = 10.08 kg, displayed as 22.2 lb
Vegetarian main: 17.64 × 0.20 = 3.528 kg, displayed as 7.8 lb
Buffered servings: ceiling of 50.4 = 51
Calculator result
Catering portions
- Guests
- 45 people
- Main food per guest
- 350 g
- Side food per guest
- 200 g
- Buffer
- 12%
- Vegetarian share
- 20%
38.9 lb
main food needed
- Sides
- 22.2 lb
- Vegetarian main
- 7.8 lb
- Buffered servings
- 51
The 7.8 lb of vegetarian main sits inside the 38.9 lb. The other main is 38.9 − 7.8 = 31.1 lb. Adding 7.8 on top of 38.9 double-counts the vegetarian guests. Example 7 does that mistake on purpose.
Main plus sides is 38.9 + 22.2 = 61.1 lb. Main is 38.9 ÷ 61.1 = 63.7% of that weight. Sides are 36.3%.
Fig 2 · 1/2
61.1 lb, main and sides
45 guests, 350 g main, 200 g sides, 12% buffer
Main
38.9 lb
Sides
22.2 lb
Main food is 38.9 lb.
Sides add 22.2 lb. The vegetarian 7.8 lb is already inside the main.
The servings line says 51, and the kilograms were built from 50.4. One extra serving on the count does not add another 350 g to the weight. The weight uses 50.4 throughout.
Example 2: a dinner for 8
- guests: 8
- main: 300 g
- sides: 150 g
- buffer: 10%
- vegetarian share: 0%
Factor: 8 × 1.10 = 8.8
Main: 8.8 × 0.300 = 2.64 kg, displayed as 5.8 lb
Sides: 8.8 × 0.150 = 1.32 kg, displayed as 2.9 lb
Vegetarian main: 0 lb
Buffered servings: ceiling of 8.8 = 9
Calculator result
Catering portions
- Guests
- 8 people
- Main food per guest
- 300 g
- Side food per guest
- 150 g
- Buffer
- 10%
- Vegetarian share
- 0%
5.8 lb
main food needed
- Sides
- 2.9 lb
- Vegetarian main
- 0 lb
- Buffered servings
- 9
Eight people at these grams are not 8 ÷ 45 of the default pot. The default uses 350 g, 200 g, and 12%. This dinner uses 300 g, 150 g, and 10%. Both the plate and the buffer changed, so the pot shrinks by more than the headcount.
Example 3: 120 guests
- guests: 120
- main: 400 g
- sides: 250 g
- buffer: 15%
- vegetarian share: 25%
Factor: 120 × 1.15 = 138 exactly
Main: 138 × 0.400 = 55.2 kg, displayed as 121.7 lb
Sides: 138 × 0.250 = 34.5 kg, displayed as 76.1 lb
Vegetarian main: 55.2 × 0.25 = 13.8 kg, displayed as 30.4 lb
Buffered servings: 138, because the factor is already a whole number. The ceiling has nothing to add.
Calculator result
Catering portions
- Guests
- 120 people
- Main food per guest
- 400 g
- Side food per guest
- 250 g
- Buffer
- 15%
- Vegetarian share
- 25%
121.7 lb
main food needed
- Sides
- 76.1 lb
- Vegetarian main
- 30.4 lb
- Buffered servings
- 138
The vegetarian slice is 30.4 lb inside the 121.7 lb of main. The remaining main is 121.7 − 30.4 = 91.3 lb. At 25% of the guests, a quarter of the main weight is the vegetarian portion, and the buffer is already inside both numbers. You do not take 25% of 120 and then add 15% only to that group unless that is the menu you typed. Here the 15% buffer applies to every guest, and the 25% is a share of the finished main.
Example 4: what if I change only the buffer
Keep 45 guests, 350 g of main, 200 g of sides, and a 20% vegetarian share.
| Buffer | Factor | Main | Sides | Vegetarian main | Servings |
|---|---|---|---|---|---|
| 0% | 45 | 34.7 lb | 19.8 lb | 6.9 lb | 45 |
| 10% | 49.5 | 38.2 lb | 21.8 lb | 7.6 lb | 50 |
| 12% | 50.4 | 38.9 lb | 22.2 lb | 7.8 lb | 51 |
| 20% | 54 | 41.7 lb | 23.8 lb | 8.3 lb | 54 |
The kilograms behind the 0% row are 15.75 kg of main and 9 kg of sides. At 12% they are 17.64 kg and 10.08 kg. At 20% they are 18.9 kg and 10.8 kg.
From no buffer to the 12% default, main grows by 38.9 − 34.7 = 4.2 lb, and sides grow by 22.2 − 19.8 = 2.4 lb. From 12% to 20%, main grows by another 41.7 − 38.9 = 2.8 lb. Servings move from 51 to 54. At 10% the factor is 49.5 and the servings line is 50, one ahead of the factor, same pattern as the default.
Fig 3 · 1/2
Main and sides at three buffers
45 guests, 350 g main, 200 g sides
- Main
- Sides
| Category | Main | Sides |
|---|---|---|
| 0% | 34.7 | 19.8 |
| 12% | 38.9 | 22.2 |
| 20% | 41.7 | 23.8 |
At the 12% default, main is 38.9 lb and sides are 22.2 lb.
At 0% buffer, main is 34.7 lb. At 20%, main is 41.7 lb.
Example 5: what if I change the main portion
Keep 45 guests, 200 g of sides, a 12% buffer, and a 20% vegetarian share. Sides stay at 22.2 lb. Servings stay at 51. Only the main moves.
| Main per guest | Main | Vegetarian main |
|---|---|---|
| 250 g | 27.8 lb | 5.6 lb |
| 350 g | 38.9 lb | 7.8 lb |
| 450 g | 50 lb | 10 lb |
The factor is 50.4 in every row.
- 250 g: 50.4 × 0.250 = 12.6 kg, displayed as 27.8 lb. Vegetarian: 2.52 kg, displayed as 5.6 lb.
- 450 g: 50.4 × 0.450 = 22.68 kg, displayed as 50 lb. Vegetarian: 4.536 kg, displayed as 10 lb.
A 100 g change in the main portion is 50.4 × 0.1 = 5.04 kg, about 11.1 lb, on this guest list. From 250 g to 350 g the display moves 38.9 − 27.8 = 11.1 lb. From 350 g to 450 g it moves 50 − 38.9 = 11.1 lb again. Sides do not follow, because the side field did not change.
Example 6: adults at one portion, children at another
The formula has one portion field. A mixed guest list is two runs, added by you.
Thirty adults at the default plate, with the vegetarian share set to 0 so the slice does not confuse the add:
- factor: 30 × 1.12 = 33.6
- main: 11.76 kg, displayed as 25.9 lb
- sides: 6.72 kg, displayed as 14.8 lb
- servings: 34
Ten children, with portions you type as 200 g of main and 100 g of sides, same 12% buffer:
- factor: 10 × 1.12 = 11.2
- main: 2.24 kg, displayed as 4.9 lb
- sides: 1.12 kg, displayed as 2.5 lb
- servings: 12
Added: main 25.9 + 4.9 = 30.8 lb. Sides 14.8 + 2.5 = 17.3 lb. Servings 34 + 12 = 46.
Those 200 g and 100 g figures are inputs, not a standard child’s plate. Type the portions you mean.
The common shortcut is to count all 40 people at the adult portion. Forty guests, 350 g, 200 g, 12% buffer:
- factor: 44.8
- main: 34.6 lb
- sides: 19.8 lb
- servings: 45
Against the split, the all-adult count is 34.6 − 30.8 = 3.8 lb more main, and 19.8 − 17.3 = 2.5 lb more sides. The headcount is the same 40. The grams per child are the whole difference.
Example 7: the common mistakes
Putting the vegetarian share on top of the main
Example 1’s main is 38.9 lb, and 7.8 lb of it is the vegetarian portion. A list that reads “38.9 lb of main, plus 7.8 lb vegetarian” has ordered 46.7 lb of main. The formula’s 20% field does not do that. Set the vegetarian share to 100% and the vegetarian line becomes the whole 38.9 lb, with the main unchanged. Set it to 0% and the vegetarian line is 0 lb, with the main still 38.9 lb. The share moves food from one tray to another. It does not change the pot.
Using the ceiling as the multiplier
The default factor is 50.4, and buffered servings are 51. If you multiply grams by 51 instead of 50.4:
Main: 51 × 0.350 = 17.85 kg, about 0.21 kg over the tool’s 17.64 kg.
Sides: 51 × 0.200 = 10.2 kg, against the tool’s 10.08 kg.
The screen will still say 38.9 lb and 22.2 lb, because it used 50.4. The ceiling is a serving count. The weight uses the unrounded factor.
Dropping the buffer
At 0% the same 45 guests need 34.7 lb of main and 19.8 lb of sides. That is 4.2 lb of main and 2.4 lb of sides under the default. If the buffer was there to cover late guests and a heavy plate, a 0% run is the shopping list with that cover removed.
Scaling one recipe and calling it the party
The recipe scaler multiplies one ingredient by a serving ratio. This catering tool multiplies grams per guest. They meet only when the grams you type already match the recipe. A 4-serving recipe does not become this 45-guest pot unless you have turned the recipe into grams per person first.
Example 8: a lighter menu, and a list with no buffer
Fifty guests, smaller plates:
- main: 180 g
- sides: 120 g
- buffer: 8%
- vegetarian share: 30%
Factor: 50 × 1.08 = 54
Main: 54 × 0.180 = 9.72 kg, displayed as 21.4 lb
Sides: 54 × 0.120 = 6.48 kg, displayed as 14.3 lb
Vegetarian main: 9.72 × 0.30 = 2.916 kg, displayed as 6.4 lb
Servings: 54
Fifty guests at 180 g land under the 8-person dinner’s per-person weight, and the pot is still several times that dinner because of the headcount. 21.4 lb of main for 50 people is 21.4 ÷ 5.8 of Example 2’s main, about 3.7 times the dinner pot, from 50 ÷ 8 = 6.25 times the guests. The lighter grams are why the pot does not scale with the headcount.
Sixteen guests, the default grams, and a buffer of 0:
Factor: 16
Main: 16 × 0.350 = 5.6 kg, displayed as 12.3 lb
Sides: 16 × 0.200 = 3.2 kg, displayed as 7.1 lb
Servings: 16
Here the factor, the guest count, and the servings line are the same number. There is no 0.4 of a guest for the ceiling to round. This is the clean case. The default 45-guest run is the one where 50.4 and 51 disagree.
Fig 4 · 1/5
Main food as the guest list grows
350 g main, 200 g sides, 12% buffer, on every point
Main food (lb)
- Main
| Point | Main |
|---|---|
| 10 | 8.6 |
| 20 | 17.3 |
| 45 | 38.9 |
| 80 | 69.1 |
| 120 | 103.7 |
At 10 guests the main is 8.6 lb. At 45 guests it is 38.9 lb.
At 120 guests, same plate and same buffer, the main is 103.7 lb.
The line is straight in the formula, because main kilograms are guests × 1.12 × 0.350. The displayed pounds round to one decimal, so a step can be a tenth of a pound off a perfect line. The 45-guest point is the default, 38.9 lb. The 120-guest point on this line is 103.7 lb, which is not Example 3. Example 3 changed the grams and the buffer, and it landed at 121.7 lb.
The quantities next to each other
| Example | Guests | Main g | Side g | Buffer | Veg share | Main | Sides | Veg main | Servings |
|---|---|---|---|---|---|---|---|---|---|
| 1. Defaults | 45 | 350 | 200 | 12% | 20% | 38.9 lb | 22.2 lb | 7.8 lb | 51 |
| 2. Dinner | 8 | 300 | 150 | 10% | 0% | 5.8 lb | 2.9 lb | 0 lb | 9 |
| 3. Large | 120 | 400 | 250 | 15% | 25% | 121.7 lb | 76.1 lb | 30.4 lb | 138 |
| 4. No buffer | 45 | 350 | 200 | 0% | 20% | 34.7 lb | 19.8 lb | 6.9 lb | 45 |
| 4. 20% buffer | 45 | 350 | 200 | 20% | 20% | 41.7 lb | 23.8 lb | 8.3 lb | 54 |
| 5. Lighter main | 45 | 250 | 200 | 12% | 20% | 27.8 lb | 22.2 lb | 5.6 lb | 51 |
| 5. Heavier main | 45 | 450 | 200 | 12% | 20% | 50 lb | 22.2 lb | 10 lb | 51 |
| 6. Adults | 30 | 350 | 200 | 12% | 0% | 25.9 lb | 14.8 lb | 0 lb | 34 |
| 6. Children, typed | 10 | 200 | 100 | 12% | 0% | 4.9 lb | 2.5 lb | 0 lb | 12 |
| 6. All at adult grams | 40 | 350 | 200 | 12% | 0% | 34.6 lb | 19.8 lb | 0 lb | 45 |
| 8. Lighter menu | 50 | 180 | 120 | 8% | 30% | 21.4 lb | 14.3 lb | 6.4 lb | 54 |
| 8. No spare | 16 | 350 | 200 | 0% | 0% | 12.3 lb | 7.1 lb | 0 lb | 16 |
Open the catering portions calculator with the grams you plan to serve and a buffer you are willing to buy. Run children, or a different plate, as a second pass and add the pounds. Drinks belong on the party drink calculator, and the money for the event belongs on the birthday party budget. This tool will not tell you whether the plate is a balanced meal. It multiplies the grams you typed.