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That '100g' on European labels - what does it mean for your diet? If you've ever picked up an imported snack or tried to follow a diet plan from another country, you've probably stared at a nutrition label in confusion. The numbers don't match up. A US label might say 28g per serving with 150 calories, while the same product in Europe shows 100g with different values entirely. Neither is wrong - they just speak different measurement languages. Understanding these differences can change how you track your nutrition, whether you're counting macros, managing a health condition, or just trying to make better food choices at the grocery store.
1How US and EU Nutrition Labels Differ
The United States and European Union have fundamentally different approaches to presenting nutrition information. Neither system is better - they just prioritize different things.
The US Serving Size Approach
American labels use 'serving sizes' based on what people actually eat. The FDA calls these 'Reference Amounts Customarily Consumed' (RACCs). A serving of chips might be 28g (1 oz), ice cream is listed as 2/3 cup, and a soda serving is 12 fl oz. The problem? Serving sizes can feel arbitrary and don't always match what's in the package. A 'single-serve' bag of chips might contain 2.5 servings - forcing you to do math before you eat.
The EU Per-100g Standard
European labels show nutrition values per 100 grams (or 100ml for liquids). This makes comparing products dead simple: grab two chocolate bars, and the one with 540 calories per 100g has more calories than the one with 480. No mental gymnastics needed. However, you still need to check the package weight to know what you're actually eating. A 250g pack means you're getting 2.5 times the per-100g values.
Why This Matters for Your Health
Misreading labels can throw off your entire nutrition plan. If you're eating 'one serving' of peanut butter but actually consuming two tablespoons instead of one, you've doubled your calorie intake without realizing it. The UK Food Standards Agency found that consumers underestimate portion sizes by 30-50% on average. Understanding the measurement system is the first step to accurate tracking.
2Converting Between Label Systems
Whether you're following an American diet plan in Europe or vice versa, you'll need to convert between these systems. Here's how to do it without a calculator.
From Grams to Ounces (and Back)
The magic number is 28. One ounce equals roughly 28 grams. So a 100g European serving is about 3.5 ounces. Going the other way, multiply ounces by 28 to get grams. A 1 oz (28g) US serving is about 28% of that 100g European reference. This means you divide the per-100g values by roughly 3.5 to compare to a 1-oz American serving.
Quick Mental Math for Calories
Here's a shortcut that works 90% of the time: if a European label shows 400 calories per 100g, a typical 30g American serving would have about 120 calories (400 / 3.3). For precise calculations, multiply the per-100g value by your actual serving size in grams, then divide by 100. Example: 400 cal/100g x 45g serving = 180 calories.
The Fluid Ounce Trap
Liquids add another layer of confusion. A US fluid ounce (29.6ml) is different from an imperial fluid ounce (28.4ml). And neither has anything to do with weight ounces. When converting drink labels, focus on milliliters. One US cup equals 237ml, and most US beverage servings are listed as 8 fl oz (240ml). European drinks show values per 100ml, so a 330ml can contains 3.3 times the per-100ml nutrition.
3Practical Calorie Counting Across Countries
Tracking calories gets complicated when your food comes from different countries. Here's how to stay accurate without losing your mind.
The 100g Baseline Method
Professional dietitians recommend converting everything to per-100g values for consistency. Even when reading US labels, multiply the per-serving values to get per-100g, then compare. A US granola bar showing 190 calories per 40g serving equals 475 calories per 100g. Now you can compare it directly to any European product.
Using Food Scales Properly
The most accurate method is weighing your food. Place your bowl on the scale, zero it out (tare), then add food. Most modern apps like MyFitnessPal let you enter grams directly. A digital kitchen scale costs around $15 and eliminates all the guesswork. Weighing is especially important for calorie-dense foods: a 'handful' of nuts can range from 15g to 50g depending on your hand size.
When Labels Lie (Legally)
Both US and EU regulations allow rounding. In the US, products with fewer than 5 calories per serving can be labeled as '0 calories.' That's why cooking spray shows 0 calories - each 1/4 second spray is technically under 5 calories. But a realistic portion might be 20-30 sprays, adding 50+ actual calories. EU labels are slightly more accurate but still allow rounding to the nearest whole number.
4Reading Labels for Specific Health Goals
Different health conditions require focusing on different parts of the nutrition label. Here's what matters most for common dietary needs.
For Weight Management
Focus on calories per gram - this tells you how 'dense' a food is. Water-rich foods like fruits and vegetables have low calorie density (under 1 calorie/gram). Processed snacks and dried foods can hit 5+ calories/gram. A 30g serving of chips (150 calories = 5 cal/g) versus 30g of apple (16 calories = 0.5 cal/g) shows why whole foods fill you up for fewer calories.
For Diabetes Management
Carbohydrates are measured in grams on all labels. One 'carb serving' for diabetes management equals 15g of carbohydrates. EU labels separate 'Carbohydrates' from 'of which sugars,' giving more detail. US labels now include 'Added Sugars' separately from total sugars - this distinguishes natural fruit sugar from added sweeteners. Both systems list fiber, which can be subtracted from total carbs for 'net carbs' calculations.
For Heart Health
Sodium is listed in milligrams on both label types. The daily limit is 2,300mg (about 1 teaspoon of salt). EU labels might also show 'salt' content - multiply salt by 400 to get sodium in mg, or divide sodium by 400 to get salt in grams. Saturated fat appears on both labels; EU labels also show total fat and 'of which saturates' for easier comparison.
5Comparing Products Like a Pro
Armed with this knowledge, you can now compare any two products from anywhere in the world. Here's the systematic approach.
Step 1: Normalize to 100g
Convert both products to per-100g values. For a US product showing 150 calories per 28g serving: 150 / 28 x 100 = 536 calories per 100g. For a UK product already showing per-100g, no conversion needed. Now you can compare directly: the product with fewer calories per 100g is less calorie-dense.
Step 2: Consider What You'll Actually Eat
Per-100g values let you compare, but you need to think about real portions. A 50g chocolate bar with 550 cal/100g gives you 275 calories. A 35g bar with 500 cal/100g gives you 175 calories. The second bar is denser in calories, but the smaller size means fewer total calories. Both numbers matter.
Step 3: Watch the Protein-to-Calorie Ratio
For muscle building or satiety, check protein grams against total calories. A food with 20g protein per 200 calories (10g protein per 100 calories) is more protein-efficient than one with 15g protein per 250 calories (6g per 100 calories). Greek yogurt typically offers 10-12g protein per 100 calories, while regular yogurt offers only 3-4g per 100 calories.
Pro Tips
- 1Quick conversion: 100g equals roughly 3.5 oz - divide European per-100g values by 3.5 for approximate US serving sizes
- 2Always check the total package weight, not just per-serving values, to understand what you're actually eating
- 3For liquids: 1 cup = 237ml, so EU per-100ml values need to be multiplied by 2.37 for cup-sized portions
- 4Fewer than 5 calories per serving can legally be labeled as '0 calories' - multiple servings still add up
Food labels aren't trying to confuse you - they just follow different standards in different countries. Once you understand that EU labels show per-100g for easy comparison while US labels use serving sizes based on typical consumption, the numbers start making sense. The key insight is this: always convert to a common baseline before comparing. Whether you pick per-100g or per-ounce, consistency beats precision. And if you're serious about tracking nutrition, a $15 kitchen scale will give you more accuracy than any label ever could. Our gram-to-ounce and other converters can help you switch between systems quickly whenever you're puzzled by a foreign food label.
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