Counting calories comes down to three steps: weigh the food, look up its nutrition, and add it up. Most mistakes come from guessing portions or logging the wrong version of a food, such as raw rice instead of cooked. This guide shows how to avoid those errors and walks through a full sample day. You can follow along in our nutrition calculator, which lists calories, protein, carbs, fat and fiber for each food.
Calories for a food = (kcal per 100 g ÷ 100) × grams eaten. For example, 150 g of cooked chicken breast at 165 kcal per 100 g is 248 kcal with 46.5 g of protein.
📑 Table of Contents
Why weigh instead of guess
Portion size is where most logs go wrong. A "handful" of almonds can be 28 g or 50 g, which is about 160 kcal or 290 kcal. A kitchen scale takes a few seconds and removes that guesswork. Cups and spoons are fine when you cannot weigh, but they vary more, especially for foods that pack down such as rice or peanut butter.
The basic calculation
Nutrition data is usually given per 100 g, so you scale it to the amount you ate.
Example: oats at 389 kcal per 100 g, 40 g eaten → 389 × 40 ÷ 100 = 156 kcal
The same scaling works for protein, carbs, fat and fiber. The nutrition calculator does it for you when you pick a food and enter an amount.
Cooked or raw: log the right one
Rice, pasta and meat change weight when cooked, mostly because they absorb or lose water. Cooked rice is about 130 kcal per 100 g, while dry rice is roughly 360. If you weigh cooked food, log the cooked entry; if you weigh it dry, log the dry entry. Mixing these up is the most common way to under- or over-count by a large amount.
Pick one method per food and stick to it. Weighing everything cooked, on the plate, is often easiest.
A sample day, added up
Here is one day of food, using values from the calculator. Amounts are weights as eaten.
| Food | Amount | kcal | Protein g | Carbs g | Fat g |
|---|---|---|---|---|---|
| Rolled oats, dry | 40 g | 156 | 6.8 | 26.5 | 2.8 |
| Whole milk | 244 g (1 cup) | 149 | 7.8 | 11.7 | 8.1 |
| Banana | 118 g | 105 | 1.3 | 26.9 | 0.4 |
| Chicken breast, cooked | 150 g | 248 | 46.5 | 0.0 | 5.4 |
| White rice, cooked | 158 g (1 cup) | 205 | 4.3 | 44.6 | 0.5 |
| Broccoli, raw | 91 g | 31 | 2.5 | 6.0 | 0.4 |
| Olive oil | 14 g (1 tbsp) | 124 | 0.0 | 0.0 | 14.0 |
| Greek yogurt, nonfat | 170 g | 100 | 17.3 | 6.1 | 0.7 |
| Almonds | 28 g | 162 | 5.9 | 6.0 | 14.0 |
| Whole egg | 100 g (2 large) | 143 | 12.6 | 0.7 | 9.5 |
| Total | 1,423 | 105 | 129 | 56 |
This day comes to about 1,423 kcal, with 105 g of protein. That is lighter than most adults need, so it is an example of the method, not a meal plan. Notice that one tablespoon of olive oil (124 kcal) adds nearly as much as the banana and the broccoli combined, which is why oils are worth measuring.
Easy-to-miss calories
- Cooking oil and butter. 1 tbsp of olive oil is 124 kcal; 1 tbsp of butter is about 100 kcal.
- Drinks. A 355 g can of cola is about 149 kcal, and a cup of orange juice about 112 kcal.
- Nuts and nut butters. Dense in calories: 2 tbsp of peanut butter is about 188 kcal.
- Sauces and dressings. Small amounts add up, so weigh them when you can.
- Bites while cooking. Log what you actually eat, not just the plated meal.
Comparing the total to your target
A log is only useful when you compare it to a target. To estimate how many calories you burn in a day, use our calorie calculator or read the daily calorie needs guide. Eating below that number leads to gradual weight loss, and eating above it leads to gain. Protein and the other nutrients can be checked against the ranges in the macros guide.
Food databases and package labels are estimates, and labels are allowed to be off by a margin. Treat your total as accurate to within roughly 10% and judge progress over weeks, not single days.
Habits that keep logging simple
- Log as you eat, not at the end of the day, when you forget things.
- Save your regular meals. Most people eat the same 10 to 15 foods often.
- Weigh once, then reuse. After you know your usual bowl of cereal is 40 g, you can log it from memory.
- Do not give up after a missed meal. An approximate entry is better than a blank day.
How to use the calculator
Search for a food
Type the name, such as chicken, rice or banana, and pick the closest match.
Enter the amount
Choose grams or a serving, then add it to a meal.
Read the totals
Check calories, protein, carbs, fat and fiber for the meal and the whole day.
Log your next meal
Search a food, enter the weight and see the nutrition at once.
Open the Nutrition CalculatorFrequently Asked Questions
Conclusion
Accurate logging means weighing your food, picking the right cooked or raw entry, and adding up calories and protein. Try it with your own meals in the nutrition calculator, then compare the total with your daily needs in the calorie calculator.
This guide is general education, not medical or dietary advice. Nutrition values come from standard reference data and vary by brand and preparation. Talk to a doctor or registered dietitian before major diet changes.