How do pubs and restaurants work out calories in a meal?

[uni0]

It must be quite a rough estimate right?

Local pub has calories by each meal but they aren't really always the same size meal

They can work out the calories per ingredient and quantity and then divide by average portion size.

It will vary by serving but not radically.

Most pubs and restaurants, if they are a chain (and if they are labelling calories, they may well be as independents don’t have to label) will have specific dish specs for every dish e.g. 40g of dried pasta, 3 halved tomatoes, a ladle of sauce and so on - and these dishes will then all have been sent to labs to calculate the calories.

Obviously it relies on the chefs / food handlers putting the correct ingredients by weight / measure on the plate, but this is also how the profit margins are worked out for the dishes, so they will likely be monitored for too much / too little of an ingredient as well.

There are nutritional analysis programs in which you can input the ingredients and weight and portions, and it will work everything out.
I'm a dietitian. We use them for loads of stuff. Hospital menus, individual nutritional intakes, school meals.
If they are a big chain, it will be done centrally, one off local restaurants likely use Nutriweb or something

Chain restaurants work to fixed recipes, it's how they manage costs and margin. They employ nutritionists or consultants to calculate the nutritional values. There's software that can be used to input the ingredients and quantities and determine the calories in a cooked meal.