How many calories are in chicken breast, raw vs cooked?

The evidence

USDA FoodData Central carries two entries for boneless, skinless chicken breast. The raw entry (FDC ID 171077) lists about ≈120 calories, about ≈22.5 g protein, about ≈2.6 g fat and about ≈73.9 g water per 100 g. The cooked, roasted entry (FDC ID 171477) lists about ≈165 calories, about ≈31 g protein and about ≈3.57 g fat per 100 g — the same cut, just cooked.

The size of the jump matches USDA's own cooking data. The USDA Table of Cooking Yields for Meat and Poultry, published by the Agricultural Research Service's Nutrient Data Laboratory in 2012, measured how much weight chicken breast loses during cooking. Baked or roasted breast averaged about ≈72% of its raw weight, with individual samples ranging from 61% to 82%. Poached or simmered breast kept more of its weight, about ≈77% on average, in a range of 70% to 88%. That specific chicken listing traces back to older 1975 testing, so treat the exact range as a rough guide rather than a precise figure for any one piece of meat.

What it means in practice

Take a 200 g raw chicken breast: about ≈240 calories, using the ≈120-per-100 g raw figure. Roast it, and USDA's yield data say it will shrink to roughly 72% of that raw weight, so about ≈144 g once it's done. Weigh that cooked piece and multiply by the ≈165-per-100 g cooked figure, and you land on about ≈238 calories — close to the ≈240 you started with, within the normal spread of USDA's averages. The energy in the meat barely moved. What changed was the water.

Why the numbers differ

Raw chicken breast is mostly water — USDA lists about ≈73.9 g of water per 100 g. Heat drives much of that water out as steam, and the muscle fibres tighten and squeeze out more, the way a wrung sponge gives up liquid. The protein and fat stay behind in the meat; only the water leaves. So the same amount of energy ends up packed into fewer grams, which is why cooked chicken reads higher per 100 g than raw chicken cut from the exact same breast.

Common mistakes

The most common mix-up is matching the wrong weight to the wrong calorie value: logging a cooked, weighed piece of chicken against a raw-calorie figure, which undercounts by roughly a quarter to a third, or doing the reverse and overcounting. Either mistake adds up over a week of meals.

Cup measurements make it worse. On the chicken breast page, USDA's data puts 100 g of cooked chicken at about ≈165 calories, a 3 oz (85 g) serving at about ≈140, and 1 cup of chopped or diced cooked chicken (140 g) at about ≈231. But how tightly you pack a cup of chopped chicken changes that gram weight a lot, so the same "1 cup" can mean very different calorie counts from one plate to the next. A scale removes that guesswork; a measuring cup doesn't.

What to do instead

• Weigh raw, log raw. Weigh the chicken before it hits the pan and use a raw-chicken calorie value, about ≈120 per 100 g. This works well if you cook the same way each time.
• Weigh cooked, log cooked. Weigh the finished piece and use a cooked value, about ≈165 per 100 g for roasted chicken. This is easier when you're eating food you didn't weigh raw yourself.
• Match the cooking method if you can. USDA's yield data show poached or simmered chicken holds on to more water, about ≈77% of its raw weight, than roasted chicken, about ≈72%, so a cooked-weight estimate is a little more accurate when you know how the piece was cooked.
• Use grams, not cups, for chicken and other chopped meat. See the chicken breast page for USDA's own portion weights, and the protein calculator to check how a piece of chicken fits your daily protein target. For the bigger picture on protein needs, see how much protein do you need.