How much caffeine is in a gram of coffee grounds?

December 1, 2025 •

3 min read

A single Arabica coffee bean contains about 6 milligrams of caffeine, while a Robusta bean has about 12 milligrams, nearly double the amount. This significant difference means the amount of caffeine in a gram of coffee grounds is not a fixed number and varies based on the type of bean used.

Quick Summary

The caffeine content in a gram of coffee grounds varies significantly depending on the bean type, with Robusta coffee containing much more than Arabica. Roast level, while often debated, has a minimal impact when measured by weight. Other factors, like growing conditions and processing, also contribute to the final caffeine concentration.

Key Points

Variable Caffeine Content: The amount of caffeine in a gram of coffee grounds is not fixed and varies based on several factors, with bean species being the most significant.
Arabica vs. Robusta: Arabica beans contain significantly less caffeine per gram (approx. 11-17 mg) than Robusta beans (approx. 20-45 mg).
Weight vs. Volume Measurement: When measuring by weight, roast level has little effect on caffeine content. When measuring by volume, lighter roasts will have slightly more caffeine due to higher density.
Extraction Matters: The brewing method, water temperature, grind size, and brew time all influence how much caffeine is actually extracted from the grounds into your final beverage.
No Fixed Number: Due to the many variables involved, it's impossible to give a single, definitive number for how much caffeine is in a gram of coffee grounds without knowing the bean type.

Arabica vs. Robusta: The Biggest Difference

The species of coffee bean is the most significant factor. Arabica and Robusta are the two main species with different caffeine levels.

Arabica Beans: These beans typically contain 1.1% to 1.7% caffeine by weight, or about 11 to 17 milligrams per gram. They are grown at higher altitudes.
Robusta Beans: Containing 2% to 4.5% caffeine by weight, Robusta beans have about 20 to 45 milligrams per gram. Their higher caffeine acts as a natural pest repellent.

The Role of Roast Level

The roasting process does not significantly change caffeine content when measured by weight. The difference perceived is mainly due to measuring by volume.

By Weight: Dark and light roasts have similar caffeine amounts by weight. The caffeine mass remains largely constant.
By Volume: A scoop of light roast has slightly more caffeine by volume because dark roast beans expand and are less dense.

Factors Influencing Inherent Caffeine Content

Other factors can influence caffeine content, such as origin, growing conditions, and processing method.

Comparison Table: Caffeine by Bean Type


Feature	Arabica Beans	Robusta Beans
Caffeine per Gram (approx.)	11-17 mg	20-45 mg
Flavor Profile	Smooth, sweet, nuanced	Strong, bitter, earthy
Growing Altitude	Higher altitudes (600-2000m)	Lower altitudes (0-600m)
Cost	Generally more expensive	Generally less expensive
Pest Resistance	Lower (due to less caffeine)	Higher (due to higher caffeine)

The Extraction Process: Getting Caffeine into Your Cup

The caffeine in the grounds is not the same as in your brewed coffee. The brewing method determines how much caffeine is extracted. Extraction efficiency is influenced by brewing method, water temperature, grind size, and brew time.

Conclusion

Caffeine in a gram of coffee grounds varies based on bean species, with Arabica having less than Robusta. Roast level has minimal impact by weight but affects volume measurements. The final caffeine in your cup depends on brewing and extraction. Knowing the bean species is key to estimating caffeine per gram.

For further reading, {Link: Quora https://www.quora.com/What-are-some-of-the-many-variables-that-can-affect-coffee-s-caffeine-levels} discusses factors affecting caffeine levels. The Specialty Coffee Association also offers resources.

Keypoints

Variable Caffeine Content: Caffeine in a gram varies, mainly by bean species.
Arabica vs. Robusta: Arabica has less caffeine per gram (approx. 11-17 mg) than Robusta (approx. 20-45 mg).
Weight vs. Volume: Roast level's impact on caffeine per gram is negligible by weight but affects volume.
Extraction Matters: Brewing method, temperature, grind, and time influence how much caffeine is extracted.
No Fixed Number: A single number for caffeine per gram is impossible without knowing the bean type.

Faqs

How many milligrams of caffeine are in a gram of Arabica coffee grounds?

A gram of Arabica grounds has about 11 to 17 mg of caffeine.

How much caffeine is in a gram of Robusta coffee grounds?

Robusta grounds contain significantly more, typically 20 to 45 mg per gram.

Does a dark roast have less caffeine per gram than a light roast?

By weight, the difference is negligible. The difference by volume is due to density.

Does the grind size affect the caffeine content in the grounds?

Grind size doesn't change caffeine content but affects extraction efficiency.

Why do Robusta beans have more caffeine than Arabica beans?

Robusta's higher caffeine acts as a pest defense at lower altitudes; Arabica has fewer pests at higher altitudes.

Is the caffeine in the grounds the same as the caffeine in my brewed coffee?

No, not all caffeine transfers to the brewed coffee. Extraction depends on brewing factors.

Can I calculate my caffeine intake from the weight of my coffee grounds?

You can estimate potential caffeine based on bean type and weight, but final cup content depends on brewing.

Frequently Asked Questions

An average gram of Arabica coffee grounds contains approximately 11 to 17 milligrams of caffeine, although this can vary.

One gram of Robusta coffee grounds typically contains a much higher amount of caffeine, ranging from 20 to 45 milligrams, which is nearly double that of Arabica.

When measured by weight, the caffeine difference between a dark and light roast of the same bean species is negligible. The misconception arises from measuring by volume, where the denser light roast beans pack more weight into a scoop.

No, the grind size itself does not change the amount of caffeine present in the grounds. However, a finer grind size can lead to a more efficient extraction of caffeine during brewing because of the increased surface area.

Robusta plants grow at lower altitudes and use their higher caffeine content as a natural defense mechanism against pests, whereas Arabica plants face fewer pests at higher altitudes and thus produce less caffeine.

No, the total caffeine in the grounds is not fully transferred into your cup. The brewing process extracts a certain percentage of that caffeine, with the extraction rate depending on factors like brew time, water temperature, and grind size.

Yes, you can get a rough estimate of the potential caffeine in your grounds by knowing the bean species and weight. However, to know how much is in your final cup, you would also need to consider your specific brewing method and extraction efficiency.