How do you count calories?

Reviewed 4 November 2026 · How these numbers are calculated

How do you count calories? Step by step

1. Find your target. Use the calculator above (or the maintenance calorie calculator for your starting point). It builds your maintenance from your steps and workouts and subtracts a deficit that matches your weight. For the example woman: maintenance 1,830, target 1,450 (how many calories to eat to lose weight; background: what is a calorie deficit?).
2. Choose an app. Any one with a large database and a barcode scanner will do. The best app is the one you'll open every day. Pick one and stay with it for a few weeks.
3. Weigh your food in grams. A cheap kitchen scale is the biggest accuracy upgrade. Cups and spoons are rough. Tare the bowl, add the food, log the grams.
4. Log everything, right away. Include cooking oil, butter, sauces, dressings, coffee with milk, drinks, tastes while cooking and bites of other people's food. Log before you eat, not at the end of the day.
5. Read labels, and the serving size. Label calories are per serving, and the serving may be half a pack. Check the "per 100 g" column and the number of servings.
6. Estimate eating out. Log a similar dish from a chain restaurant and add 10–20% for oil and portion size, or pre-log what you'll order. Don't skip a day because you can't be exact; a rough entry is better than none.
7. Check the weekly weight trend and adjust. Weigh yourself a few times a week and compare weekly averages. If the 2–3 week trend doesn't match your target pace, change your intake by 100–200 calories, or re-check what you log. Details: calorie deficit but not losing weight.

Which foods are the hidden calories?

Most under-counting is in fats and sauces, because they are dense and easy to eyeball wrong. These are typical servings from USDA data:

See also low-calorie foods for volume at a low cost, and high-protein foods.

Raw or cooked weight?

Weigh food the way your app's entry says. Cooked rice, pasta and oats hold water, so 100 g cooked is much lower in calories than 100 g dry. For example, 100 g of cooked white rice is 130 calories; weighed dry it has roughly 2–3 times more per 100 g, about 260–390. Meat loses water when cooked and the calories per 100 g go up. Use raw weights with a "raw" entry and cooked weights with a "cooked" entry, and don't mix them.

How accurate are calorie labels?

Not exact. In the US the FDA lets packaged food contain up to about 20% more calories than the label says (21 CFR 101.9(g)), and tests of packaged and restaurant meals found measured calories on average 18% above the stated values in restaurant meals and 8% above in frozen supermarket meals, with some items at double (Urban et al., 2010). Your count is therefore an estimate with an error bar. That's fine: what matters is being consistent, then adjusting from your weight trend.

Why do people undercount?

In a classic study of people who said they couldn't lose weight on little food, participants under-reported what they ate by nearly half on average (47%) and over-reported exercise (Lichtman et al., 1992). Most of us forget the oil, the handful of nuts, the weekend drinks. Weighing and logging at the time of eating cuts the error. If your numbers say deficit but the scale doesn't move for 3–4 weeks, the log is what to doubt first (CICO: net calories).

Can you count calories without an app?

Yes, roughly, with your hand as the scale:

Another method: fix a few meals you repeat and know their numbers. Many people eat the same 6–10 breakfasts and lunches. Don't use exercise calories to raise your target without reading should you eat back exercise calories?

Does counting calories work?

For most people, yes: a systematic review found that tracking what you eat was consistently linked with more weight loss, though most of the studies were small or observational (Burke et al., 2011). It works because it makes the deficit visible. It's not the only way, but it's the most direct. You don't have to do it forever: many people count carefully for 4–8 weeks to learn portions and then ease off. To track protein, carbs and fat as well, see how to count macros.

When shouldn't you count calories?

Don't count calories if you have, or have had, an eating disorder, or if counting makes you anxious, makes you skip meals or guilty about eating. Counting can trigger or worsen disordered eating. If you're unsure, ask a doctor or a registered dietitian first. It's also not meant for pregnancy, under-18s or people with medical conditions that affect weight; see a clinician instead.

Sources

• U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy (2018).
• Lichtman SW, Pisarska K, Berman ER, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med 1992;327(27):1893–1898.
• Burke LE, Wang J, Sevick MA. Self-monitoring in weight loss: a systematic review of the literature. J Am Diet Assoc 2011;111(1):92–102.
• Urban LE, Dallal GE, Robinson LM, et al. The accuracy of stated energy contents of reduced-energy, commercially prepared foods. J Am Diet Assoc 2010;110(1):116–123.
• U.S. Food and Drug Administration. Nutrition labeling of food, 21 CFR 101.9(g) (compliance with declared nutrient values).