Green Bean Casserole for 20

How much green bean casserole for 20 people

The classic green bean casserole starts as a six-serving dish: one 10.5 oz can of condensed cream of mushroom soup, half a cup of milk, a teaspoon of soy sauce, four cups of cooked green beans and one and a third cups of French fried onions. Feeding 20 means multiplying every amount by 3.33, and then rounding up to whole cans, because nobody sells two thirds of a can.

The calculator above does that rounding for you. It starts from the six-serving recipe and scales to whatever headcount you enter, then reports the amounts in the units you buy: cans of soup, cups of milk, cans of green beans and cans of fried onions. It also tells you how many pans to bake in.

• Cream of mushroom soup: 3.33 cans, so buy 4.
• Milk: 1.67 cups.
• Green beans: 13.3 cups, which is 7 cans of 14.5 oz drained.
• French fried onions: 4.4 cups, about two 6 oz cans.

Those numbers assume a standard side-dish portion of about one cup per person. A holiday plate with a big slice of turkey and three other sides needs less, and a potluck where the casserole is the star needs more. The portion selector in the calculator adjusts the whole list in one step. The USDA Food Safety and Inspection Service is the reference we use for the food-safety side of holding a dish warm.

Worked example: the full shopping list for 20

Here is the complete list for 20 people at a standard portion, built from the six-serving base recipe. Every figure is what the calculator returns when you set servings to 20.

The pan math is separate. A 9x13 pan holds about 12 servings at one cup each, so 20 servings needs two pans, or one 9x13 plus one 8x8. Two shallower pans also beat one deep dish, because a deep casserole leaves the center underdone while the edges boil. Bake at 350 degrees F for 30 to 35 minutes, stir once at the halfway mark, then scatter the onions over the top and bake 5 minutes more.

The cost lands near $12 to $16 at typical US supermarket prices: about $5 for the soup, $3 for the beans, $2 for the milk and soy, and $4 to $6 for the fried onions. That is under a dollar a serving for a dish that feeds a holiday table.

Worked example: scaling to 30 or down to 12

The same factor works at any size, which is the point of a calculator over a recipe card. For 30 people you multiply the base by 5:

• Soup: 5 cans
• Milk: 2.5 cups
• Green beans: 20 cups, or 10 cans of 14.5 oz
• Fried onions: 6.67 cups, so 3 cans of 6 oz
• Pans: 30 servings at 12 per pan is 3 pans

For 12 people the factor is 2, which is a straight double: 2 cans of soup, 1 cup of milk, 8 cups of beans (4 cans) and 2 2/3 cups of onions. One 9x13 pan is exactly right at 12 servings, so there is no waste and no second pan to wash.

The one place scaling gets slippery is the topping. At six servings the topping is a thin, crisp layer; at 30 it is a thick blanket that steams the beans underneath if you add it too early. Add the onions only for the final 5 minutes no matter how big the batch, and keep them in a single even layer rather than a pile. If you want extra crunch, buy one more can than the math calls for and pass it at the table.

Green bean casserole amounts at a glance

Use this table to skip the calculator for common party sizes. Amounts assume a one-cup side portion and are rounded up to whole cans.

Two patterns are worth remembering. First, the soup scales a little faster than the beans, because one can of soup covers six servings while two cans of beans cover six, so at large sizes you end up with slightly more soup per person. Second, the onions scale the slowest of all, so a 50-serving batch uses 5 cans, not the 8 that a straight multiplication of the six-serving count would suggest. Both effects come from the recipe ratios, and the calculator applies them exactly.

Make-ahead and holding it warm safely

A 20-serving casserole is a party dish, which means you assemble it before guests arrive. Mix the soup, milk, soy sauce, pepper and beans in a large bowl, spread it into the pans, cover with foil and refrigerate for up to 24 hours. Do not add the fried onions yet; they turn soft and oily overnight.

On the day, move the pans to the counter about an hour before baking so they are not ice cold, then bake covered at 350 degrees F for 30 to 35 minutes. Uncover, add the onions and bake 5 minutes more. If you are holding it for a buffet, keep it at 140 degrees F or above in a 200 degree F oven or a slow cooker set to warm. The FoodSafety.gov guidance is clear that hot food should stay at 140 degrees F or higher and should not sit at room temperature for more than 2 hours. The FDA food pages cover the same two-hour rule for perishable dishes.

If you are transporting it, bake it fully at home, wrap the pan in towels inside a cooler, and it will hold above 140 degrees F for about an hour. Cold green bean casserole is safe to reheat once, to 165 degrees F, but do not reheat it twice.

What to buy and what to skip

For a crowd, canned green beans are the practical choice: 7 cans against trimming, blanching and cooking about 3.5 pounds of fresh beans. If you do go fresh, trim the ends, cut into 1-inch pieces and blanch for 4 minutes, then drain well before mixing. Frozen cut beans work too and need no blanching, about 13 cups straight from the bag.

• Skip the extra salt. Canned beans and condensed soup are already salty, so add pepper and taste before you season.
• Buy low-sodium soup if you like. Two cans of the regular and two of the low-sodium version is a common middle ground.
• Do not treat a can of green beans as two cups. A drained 14.5 oz can is close to 1.9 cups, not 2, so weigh or measure rather than counting cans loosely.
• Keep one spare can of onions. Someone always wants more topping, and they are the cheapest item on the list.

Everything here is an estimate for planning a party; taste and adjust as you go. All of the math runs in your browser, and nothing you type is uploaded.