How many calories in a cup of Greek yogurt?

The evidence

USDA FoodData Central carries three separate entries for plain Greek yogurt. Nonfat (FDC ID 170894) lists about ≈59 calories, ≈10.2g protein, ≈0.4g fat per 100g. Lowfat, roughly 2% (FDC ID 170903), lists about ≈73 calories, ≈10.0g protein, ≈1.9g fat per 100g. Whole milk (FDC ID 171304) lists about ≈97 calories, ≈9g protein, ≈5g fat per 100g. Protein barely moves across the three. The calorie difference between nonfat and whole milk, about ≈38 per 100g, is almost entirely fat.

Harvard Health Publishing's own comparison, using a 6 oz (≈170g) serving, lists about 104 calories for nonfat, 120 for low-fat, and 160 for whole milk. That's close to what the USDA per-100g figures work out to. The small gap is brand-to-brand variation, not a disagreement in the science.

The "cup" problem

Here's what most calorie pages skip. USDA gives regular, plain low-fat yogurt, a thinner and more pourable product, an official "1 cup (245g)" portion, worth about ≈154 calories. None of the three Greek yogurt entries has a cup portion at all. The only household measures USDA lists for Greek yogurt are containers: 170g for the nonfat and whole milk versions, 200g for the lowfat one. Greek yogurt is strained to remove whey. That's part of why it's sold by weight on the tub, not scooped by the cup.

US food-labeling rules back this up. Under 21 CFR 101.12, the FDA's reference amount for yogurt is 170g, labeled on packaging as a fraction of a cup, not a full cup. That 170g figure is also why so many single-serving yogurt containers, Greek or not, land around 150-170g.

What it means in practice

Take that 170g reference serving across the three fat levels: nonfat comes to about ≈100 calories (59 × 1.7), low-fat to about ≈124 (73 × 1.7), and whole milk to about ≈165 (97 × 1.7).

Now compare that with what you'd get if you mistakenly applied regular yogurt's 245g cup weight to Greek yogurt instead: nonfat would look like about ≈145 calories, and whole milk about ≈238. That's 40-45% higher than the 170g container figure, for a product that doesn't actually come in a 245g cup. That gap is the whole reason "a cup of Greek yogurt" doesn't have one clean answer.

An 8 oz (227g) container, which some brands do sell, lands in between: about ≈134 nonfat, ≈166 lowfat, ≈220 whole milk.

Common mistakes

• Borrowing the regular-yogurt cup weight. Using 245g for Greek yogurt overstates calories by roughly 100g worth of product, because Greek yogurt containers run smaller.
• Ignoring the label's serving size. Harvard Health's advice is to check the label and compare serving sizes directly, since single containers range from about 5 to 8 oz (142-227g) brand to brand.
• Assuming "low-fat" and "nonfat" are close. They're closer to each other than whole milk is to either, but the ≈14-calorie-per-100g gap between nonfat and low-fat still adds up over a week of breakfasts.

What to do instead

• Check the container's weight in grams on the label, and multiply by the per-100g figure for your fat level rather than guessing a cup weight.
• If you want a true 1-cup (245g) yogurt and the calorie figure to match it, that's the USDA figure for regular, unstrained plain yogurt, not Greek.
• For Greek yogurt specifically, use the Greek yogurt page for USDA's per-100g and per-container numbers. Then check the protein calculator to see how a serving fits your daily protein target — protein is where Greek yogurt earns its reputation, regardless of fat level.