How to Count Calories and Macros in a Home-Cooked Dish: Weigh the Pot, Then Your Plate

A packet of rice has a label. A pot of chicken and rice you just cooked does not. Most people guess, pick something similar from a database, or give up on logging dinner. There is a better way, and it needs a kitchen scale and three weighings: the raw ingredients, the finished pot and your plate. Below is the method with a fully worked example, every number traceable to its source, and the two checks that catch most typos.

Why raw weights alone give the wrong answer

Calories don’t change much when you cook. Weight does. Rice and pasta drink water, so they get heavier. Meat loses water, so it gets lighter. Some water simmers away. The calories in the pot are still the sum of what went in, but the pot no longer weighs what went in. If you divide the dish by its raw weight and then weigh a cooked portion, you are dividing by the wrong number.

The same trap catches single foods. USDA FoodData Central lists dry long-grain white rice at 365 kcal per 100 g and cooked rice at 130 kcal per 100 g. Same rice, roughly 2.8 times the weight once cooked. Use the value that matches the state the food is in when you weigh it.

The method in three weighings

1. Weigh every ingredient raw, as it goes into the pot, and use raw (or dry) values per 100 g. Labels describe the product as packed, so this is the state they match. Don’t skip the oil.
2. Weigh the finished dish. Weigh the empty pot once and write its weight on a piece of tape under the lid, then weigh the full pot after cooking and subtract. Do it before anyone serves themselves.
3. Weigh your plate and take its share: the dish’s calories and macros × your grams ÷ the cooked weight.

A worked example: chicken, rice and peppers

One pot, five ingredients plus water. Each row is the USDA value per 100 g × the grams in the pot ÷ 100. Water has no calories, so it adds weight to the pot but nothing to the total.

The values per 100 g, all from USDA FoodData Central: raw chicken breast 120 kcal, 22.5 g protein, 2.62 g fat; dry long-grain rice 365 kcal, 7.13 g protein, 0.66 g fat, 79.95 g carbs; raw onion 40 kcal, 1.1 g protein, 0.1 g fat, 9.34 g carbs; raw red pepper 26 kcal, 0.99 g protein, 0.3 g fat, 6.03 g carbs; olive oil 884 kcal and 100 g fat. So the rice row is 365 × 250 ÷ 100 = 912.5, rounded to 913 kcal.

After cooking, the pot minus its own weight reads 1,340 g, not 1,060. That is about what the USDA numbers predict: 100 g of dry rice ends up as roughly 280 g cooked (365 ÷ 130), so the 250 g of rice became about 700 g, while 100 g of raw chicken breast shrinks to about 73 g (120 kcal raw against 165 kcal roasted), so the chicken lost about 135 g. Your pot will weigh something different, which is the whole point of weighing it.

You put 400 g on your plate. Its share is 400 ÷ 1,340 of the pot, about 30 %:

• Calories: 1,693 × 400 ÷ 1,340 = 505 kcal
• Protein: 133.4 × 400 ÷ 1,340 = 39.8 g
• Fat: 25.5 × 400 ÷ 1,340 = 7.6 g
• Carbs: 221.3 × 400 ÷ 1,340 = 66.1 g

The number of servings never came into it. That is deliberate: “a quarter of the pot” is a guess, 400 g on a scale is not, and tomorrow’s portion from the same pot is the same sum with a different plate weight.

What happens if you skip weighing the pot

Divide by the raw 1,060 g instead and the same plate comes out at 1,693 × 400 ÷ 1,060 = 639 kcal, 134 kcal more than it really holds, about a quarter too high. A dish that soaks up water (rice, pasta, porridge, lentils) gets over-counted this way. A dish that loses water (a meat stew, a tray of roasted vegetables) gets under-counted. Either way, one extra weighing fixes it.

Two checks that catch most typos

Home-made numbers are only as good as what you type in. Two quick checks catch most of the mistakes.

The 4/4/9 check. Protein and carbs carry about 4 kcal per gram, fat about 9. Run the whole dish through it: 133.4 × 4 + 221.3 × 4 + 25.5 × 9 = 1,648 kcal, within 3 % of the 1,693 kcal from the table. A gap of a few percent is normal, because USDA and food labels use food-specific factors, not a flat 4/4/9. A gap of a third or more means a number was mistyped.

The kJ trap. Most European labels print energy in kilojoules first and kilocalories second, and 1 kcal = 4.184 kJ. Dry rice is 1,527 kJ or 365 kcal per 100 g. Type 1,527 into a kcal field and the 250 g of rice alone counts as 3,818 kcal instead of 913, and the whole pot jumps to about 4,600 kcal. If a value looks about four times too high, it is probably kJ.

Common mistakes

• Weighing cooked rice and logging dry values. 200 g of cooked rice is about 260 kcal; logged as dry rice it shows 730.
• Forgetting the fat in the pan. 10 g of olive oil is 88 kcal. Weigh it or measure it, then log it.
• Forgetting to subtract the pot. A heavy pot can weigh more than the food in it.
• Weighing after the first portion is gone. Weigh the full pot first, or add the served portions back in.
• Leftovers that changed. If the dish dries out in the fridge or you add water when you reheat it, weigh it again.

Doing it in Swoodie: My recipes

Everything above is arithmetic, and arithmetic is what an app is for. In Swoodie, My recipes lets you build the dish once from its ingredients and then log only the grams on your plate:

1. Open Favorites, tap “Mine”, then “Create recipe”. Add each ingredient with “Search products”, “Scan a barcode”, or “Add my own ingredient” with the values per 100 g from the package, and type the grams you put in.
2. After cooking, tap “Weigh the pot” and enter the weight of the finished dish. Skip it and Swoodie counts from the raw ingredients’ weight and tells you so.
3. When you eat, “How much did you eat?” opens on “Grams”: type 400 and log it. The share of the pot is worked out for you. You can also get there from the + button, under “My recipes”.

You can edit an ingredient’s calories and macros at any time, and Swoodie points out values that look off, such as kJ typed as kcal (“This looks like kJ, not kcal”), protein, fat and carbs adding up to more than 100 g per 100 g, calories that don’t match the macros, or an unusual amount. They are hints, not a guarantee, so a quick look at the label still pays off. On Premium you can also paste a whole recipe with amounts (“Paste a recipe”) and correct the list it makes. Your own recipes stay private to your account.

Don’t want to weigh at all?

Weighing pays off for dishes you cook again and again. For everything else, a photo is often close enough: see how AI photo calorie counting works. To set the targets these numbers count toward, start with how to set your macros or the free Macro Calculator.

This is general nutrition information, not medical or dietary advice. Food values vary by product and brand; the figures here are USDA FoodData Central reference values.

Get Swoodie on iOS or Google Play, and count your next pot once instead of guessing it every night.