While coffee is loved for its aroma, flavour, and comforting warmth, most people reach for a cup to enjoy one key ingredient: caffeine. This natural stimulant is what gives coffee its energising kick that most of us crave first thing in the morning.
However, not all coffee contains the same amount of caffeine. Levels can vary widely across bean type, roast, brew method, and serving size.
What is Caffeine and How Does It Work?
Caffeine is the natural compound that sharpens our focus and boosts our alertness and is found in coffee beans, tea leaves, cacao, and other plants. Its effectiveness is its ability to block adenosine - a chemical in the brain that’s responsible for making you feel tired. As a result, caffeine allows neurotransmitters like dopamine and norepinephrine to increase, which improves concentration, energy, and even our mood.
How Much Caffeine is in a Cup of Coffee?
On average a cup of coffee contains 70–140 milligrams (mg) of caffeine but depending on the type and brewing style this can wildly fluctuate. For example:
- Espresso (1 oz): 63 mg
- Drip coffee (8 oz): 95 mg on average
- Cold brew (8 oz): 150–240 mg, depending on steeping time
- Instant coffee (8 oz): 60–90 mg
- Decaffeinated coffee (8 oz): 2–5 mg
Espresso is the most concentrated of the coffee types, but due to its small serving size it contains less caffeine in total than a full cup of drip or cold brew coffee.
Bean Type Matters: Arabica vs. Robusta
Coffee beans come primarily from two species: Arabica and Robusta. Known for their smooth flavour and low bitterness, Arabica beans contain about 0.8–1.4% caffeine by weight while Robusta beans, pack a punch with 1.7–2.7% caffeine - almost double the amount. This is why Robusta is the common choice for espresso blends and instant coffee.
Does the Roast Level Affect Caffeine?
It’s common to assume that the darker the roast, the higher the caffeine level, but this notion is nothing more than a myth. Roast level affects taste, not caffeine content so the lightest roast can contain roughly the same amount of caffeine as the darkest per bean. However, dark roasts are less dense, so a scoop of light roast might deliver slightly more caffeine by volume, while a scoop by weight would be similar.
Brewing Method and Serving Size
A factor that influences caffeine content greatly is the way the coffee is brewed. The longer the coffee grounds are in contact with water, the more caffeine is extracted. For example, cold brews can be steeped for up to 24 hours, resulting in a highly caffeinated drink while espresso is made with high pressure and in a very short time, concentrating caffeine into a small shot.
Safe Daily Caffeine Limits
Surprisingly, it is recommended for adults to consume 400mg of caffeine, due to the health benefits it provides. This is equivalent to four standard cups of brewed coffee. Health experts suggest however, that pregnant individuals and those sensitive to caffeine should limit their intake to just 200 mg or less daily. To find out more, shop Inglewood Coffee Roasters today.