What’s Actually in Your Cup? Coffee Nutrients Breakdown

You’ve sipped your morning cup for years, but have you ever wondered what’s really in it? Beyond the aroma and caffeine kick, coffee contains a surprising mix of compounds — some familiar, others less so. If you’ve ever Googled ‘what’s in a cup of coffee?’, you’re not alone. Most drinkers focus on taste or energy, but understanding what’s actually in your brew can change how you think about it.

The short answer: in 100 grams of brewed coffee liquid, 99.5g is water. The rest includes 0.2g protein, 0.1g fat, 0.1g ash (minerals), trace sugars, and key micronutrients like 3mg calcium, 4mg phosphorus, 2mg sodium, 0.01mg vitamin B2, and 0.3mg niacin. That same 100g also holds 0.04g caffeine and 0.06g tannins (tannic acid) when made with 10g of coffee grounds.

What’s in a Cup of Coffee? The Core Components

Coffee isn’t just caffeine and water. It’s a complex liquid with seven major types of compounds: caffeine, tannins (also called tannic acid or polyphenols), fats, proteins, sugars, fibers, and minerals. These all come from the coffee bean and develop during roasting and brewing, though many break down or dissolve differently. Not all make it into your cup in meaningful amounts — but they’re all part of coffee’s chemical makeup.

Nutrition Facts Per 100 Grams of Brewed Coffee

When analyzing brewed coffee as a liquid — the stuff you actually drink — the breakdown per 100 grams is extremely lean. Here’s the full detail:

• Water: 99.5g
• Protein: 0.2g
• Fat: 0.1g
• Ash (Minerals): 0.1g
• Sugars: Trace amounts
• Calcium: 3mg
• Phosphorus: 4mg
• Sodium: 2mg
• Vitamin B2 (Riboflavin): 0.01mg
• Niacin (Vitamin B3): 0.3mg

That’s right — almost all of what you’re drinking is water. The solids left contribute barely anything by weight, but they include some essential micronutrients and compounds linked to coffee’s taste, aroma, and physiological effects.

Caffeine and Tannins: The Active Compounds

Using 10 grams of coffee grounds brewed into about 100 grams of liquid (a typical single cup), extraction yields approximately 0.04g (40mg) of caffeine and 0.06g (60mg) of tannins. These numbers can vary based on brew method, time, and grind size — but they reflect standard extraction conditions. Caffeine is, of course, the stimulant most drinkers seek, while tannins contribute to coffee’s astringency and antioxidant properties.

Why These Numbers Matter

Most people don’t drink coffee for its nutritional value — but knowing what’s actually inside helps explain its effects. The low protein, fat, and sugar content is why black coffee has almost no calories. The presence of minerals like calcium and phosphorus, though minimal, contributes to coffee’s minor dietary footprint. Meanwhile, caffeine and tannins are the heavy lifters when it comes to both flavor and function. Understanding these components lets you better evaluate claims about coffee’s health effects or adjust your brew for taste and impact.

Frequently Asked Questions

How much caffeine is in 100g of brewed coffee?

About 0.04g, or 40mg. This is based on brewing 10g of coffee grounds into roughly 100g of liquid. The actual caffeine content may vary depending on the coffee bean origin, roast level, and brew time, but this figure reflects a standard home or café brew.

What minerals are in a cup of brewed coffee?

Brewed coffee contains small amounts of calcium (3mg per 100g), phosphorus (4mg), and sodium (2mg). There are also trace minerals in the ash content (0.1g per 100g), though these are present in very low concentrations overall.

Does brewed coffee contain sugar?

Yes, but only in trace amounts. The sugar content in brewed coffee is so low it’s typically rounded to “negligible” on nutritional labels. Most of the sugars from the coffee bean are not extracted during normal brewing.

What’s the difference between tannins and caffeine in coffee?

Tannins (or tannic acid) are polyphenolic compounds that contribute to coffee’s astringency and bitterness, as well as some antioxidant effects. Caffeine is a stimulant compound responsible for the energizing effect of coffee. Both are extracted during brewing, with tannins contributing to mouthfeel and caffeine to alertness.

Is there fat in brewed coffee?

Very little. Brewed coffee contains just 0.1g of fat per 100g of liquid. Most of the oils from coffee beans remain in the grounds or are not fully extracted unless using methods like espresso or French press, which can pull more coffee oils into the cup.

Recommended FrontStreet Beans for Nutrient Transparency

For coffee enthusiasts curious about what’s really in their cup, try FrontStreet Coffee’s Ethiopia Humbera — bright with citrus and floral tones, showcasing coffee’s natural acidity without added sweetness. Pair it with Yirgacheffe for a classic light roast profile full of berries and lemon zest. Or explore PWN Golden Mandheling for a heavier body and spicy-sweet depth. All three highlight coffee’s inherent compounds without masking them. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.