The caffeine content in a cup of coffee varies depending on a variety of factors. The type of coffee bean used, the brewing method, the coffee-to-water ratio, and the extraction time all affect how much caffeine is in a cup of coffee.
The strongest type of coffee bean is peaberry robusta, and the strongest brew is ristretto.
Read on to learn more about robusta coffee and the caffeine content of ristretto and your favorite coffees…
What Coffee Bean Produces the Most Caffeine?
The coffee bean that produces the most caffeine is robusta, harvested from the Coffea canephora plant. Robusta beans are famed for their high caffeine content, which is almost double that of arabica beans (Coffea arabica).
On average, roasted robusta beans contain somewhere between 2.2% and 2.7% caffeine by weight. Compared to arabica beans, which contain between 1.2% to 1.5% caffeine, robusta is quite potent. These figures translate to around 22–27 mg of caffeine per gram of robusta compared to 12–15 mg per gram of arabica.
A typical 8 oz (240 mL) cup of freshly brewed robusta coffee contains 140–200 mg of caffeine. However, this can vary depending on the coffee-to-water ratio and the type of brewing method used. This is significantly more than the average cup of arabica, which contains caffeine in the region of 70–130 mg.
What is Robusta Coffee Used for?
Robusta beans are often selected for instant coffee, Vietnamese coffee, and high-strength arabica and robusta blends. Compared to arabica coffee, robusta is much less sweet and more bitter in terms of flavor. Robusta brews have dark, nutty, earthy, and chocolatey flavor profiles — milk, sugar, or condensed milk is often needed to mellow out the robust, bold flavors of this brew.
While arabica dominates specialty coffee markets due to its sweet, mellow flavor, robusta is favored for its resilience, high yields, and strong caffeine content. It's becoming more popular in the West as growing and processing methods continue to improve the quality of the beans.
For people seeking a strong caffeine boost, robusta coffee is the perfect choice. However, its bold and occasionally overpowering flavor may not appeal to everyone.
Robusta & Other Coffee Beans Compared
Robusta coffee is considered to contain the highest caffeine level per gram. So, how does this compare to other types of coffee?
Check out the table below to see how each bean weighs up:
|
Coffee Type |
Caffeine per Gram of Coffee |
Caffeine per Cup of Coffee (8 oz/240 mL) |
|
Arabica |
12–15 mg |
70–130 mg |
|
Robusta |
22–27 mg |
140–200 mg |
|
Peaberry Robusta |
24–27 mg |
160–220 mg |
|
Liberica |
8–12 mg |
70–90 mg |
What Brewing Method Makes the Strongest Coffee?
When it comes to brewing strong coffee, the espresso machine is king. This coffee maker forces hot water under pressure through finely ground coffee to extract a concentrated shot of coffee.
Espresso is one of the strongest brews out there. However, it has an even more potent relative — the ristretto.
A ristretto is made the same way as an espresso. However, it has a 1:1 coffee-to-water ratio (the espresso has a 1:2 ratio). Ristretto is also brewed for a shorter amount of time — 15–20 seconds rather than the 20–25 seconds required for espresso.
The higher coffee-to-water ratio and reduced brewing time of the ristretto result in a more concentrated shot of coffee with less liquid volume.
A shot of ristretto coffee made with arabica contains 75–90 mg of caffeine. A double shot contains 140–180 mg. A ristretto brewed with a robusta and arabica blend may be even stronger — with up to 250 mg of caffeine in a double shot (depending on the blend).
Ristretto is known for its intense, thick, bold flavor. Compared to an espresso it's naturally sweeter and less bitter due to the shorter extraction time. However, the intense, concentrated coffee flavor can be overpowering for some.
Different Coffee Brews and Their Caffeine Content (Ranked)
Different brews contain different caffeine levels. The brewing methods used require different grind sizes, coffee-to-water ratios, and extraction times — all factors that affect the strength of a cup of coffee. Below we've ranked the most common different brews on the caffeine content.
Here’s how the caffeine content compares in different brews:
- Ristretto — 64 mg/oz
- Espresso — 63 mg/oz
- Moka Pot Coffee — 50 mg/oz
- Aeropress Coffee — 45 mg/oz
- Phin Filter (Vietnamese Coffee) — 40 mg/oz
- Cold Brew — 35 mg/oz
- Percolator Coffee — 30 mg/oz
- Pour-Over Coffee — 25 mg/oz
- Vacuum Pot Coffee — 22 mg/oz
- French Press — 20 mg/oz
- Drip Coffee — 12–16 mg/oz
- Instant Coffee — 8–12 mg/oz
- Flat White — 8–12 mg/oz
- Cappuccino — 8 mg/oz
- Latte — 5–8 mg/oz
- Mocha — 5–7 mg/oz
Note: The above figures are an average. The exact caffeine content of a brew can vary dramatically depending on the bean used, coffee-water ratio, and exact extraction time.
Does Coffee Roast Level Affect Caffeine Content?
The roast level has a significant impact on the flavor profile of coffee. However, it doesn't impact the caffeine content as much as people think.
Many people assume that darker roasts contain more caffeine than lighter roasts due to the bold, strong-tasting brews they create. However, caffeine is relatively stable during the roasting process — a light roast arabica will contain (more or less) the same amount of caffeine as a dark or medium roast.
FAQs: The Strongest Coffee
Want to learn more about the strength of coffee and the caffeine levels in different brews and beans?
Check out the answers to the frequently asked questions below:
1. What’s the Strongest Type of Coffee?
The strongest type of coffee is robusta. These beans come from the Coffea robusta species and produce around twice as much caffeine as arabica beans.
2. How Much Caffeine is in a Shot of Ristretto?
The average shot of ristretto contains around 75–90 mg of caffeine. A double shot contains 140–180 mg. This is similar to an espresso. However, a ristretto contains less water, so the concentration of caffeine is higher.
3. How Much Caffeine is in Espresso?
Espresso is a concentrated coffee made by forcing pressurized water through finely ground coffee. The average single shot of espresso made with arabica coffee contains around 75 mg of caffeine. A double shot can contain anywhere from 120 to 180 mg of caffeine.
4. How Much Caffeine is in Instant Coffee?
The caffeine content in instant coffee can vary drastically. The average serving of arabica or blended instant coffee can contain anywhere from 30 to 100 mg of caffeine. Robusta instant coffee, such as our Vietnamese instant espresso, contains around 150 mg of caffeine per serving.
5. How Much Caffeine Should You Consume Per Day?
The FDA recommends that healthy adults consume no more than 400 mg of caffeine per day. That equates to around four or five cups of regular drip coffee or around five single shots of arabica espresso.
6. How Much Caffeine is in Arabica Coffee?
Arabica coffee beans contain around 12–15 mg of caffeine per gram. The average 8 oz (240 mL) cup of arabica drip coffee contains around 70–130 mg of caffeine.
7. Does Decaf Coffee Contain Caffeine?
Although decaf coffee is meant to be “decaffeinated,” it still contains caffeine. Most decaf coffee contains trace levels of caffeine. The small amount of caffeine in decaf is unlikely to affect a healthy individual. However, those with caffeine sensitivity may experience mild stimulating effects.
8. How Much Caffeine is in Liberian Coffee?
Liberian coffee beans (Coffea liberica) contain 8–12 mg of caffeine per gram. The average 8 oz (240 mL) cup of Liberian coffee contains between 70 and 90 mg of caffeine — similar to arabica.
9. Can You Overdose on Coffee?
Technically, it is possible to overdose on caffeine. However, it's unlikely for a healthy individual because the lethal amount of caffeine is around 180 mg per liter of blood.
When you consume 100 mg of caffeine (an average cup), it raises your blood-caffeine level by around 5 mg per liter. This would mean it would take around 40 cups of coffee to cause an “overdose.”
10. Does Vietnamese Coffee Contain More Caffeine?
Yes. Vietnamese coffee uses robusta beans which contain around twice as much caffeine as arabica beans. Vietnamese coffee is also brewed with a phin filter with a relatively high coffee-to-water ratio, producing a strong, concentrated brew.
