What’s the difference between Arabica and Robusta beans?

Many people are familiar with the most common type of coffee bean in North America, the Arabica bean. It makes up 60-70% of the market globally. The Robusta bean makes up about 30% of the global market and is a bit different than the more familiar Arabica. In terms of flavor, Arabica beans have a more complex acidity to them in general, making them deeper, richer, chocolatey, sweeter, and fruitier. Arabica beans also have about twice the sugar content of Robusta, giving Arabica it’s sweeter taste. Robusta is sometimes described as having a stronger, harsher, grainy, woody or even burnt rubber flavor. Most Robusta beans are used for instant coffee, mainly because they lack the quality of better Arabica beans. However, the highest quality Robusta beans are considered very good additions to strongly flavored coffee blends and can be one of the signatures of many Italian roasters. These top-level Robusta beans have very deep and rich flavors, something Italian roasts are known for, and can be used in 5-7% of the overall mix for some Italian roasts. The demand for Arabica is generally higher than Robusta, with Arabica selling for twice the price of Robusta on average. All Arabica beans are not necessarily of the highest quality either, but because there is such a larger supply of Arabica there are  more high quality beans available for roasting good and great coffee. 

One reason these higher end Robusta beans pack an extra flavor punch is because of their higher caffeine percentage. Robusta can have anywhere from 2.2-2.7% while Arabica has only 1.2-1.5%. They also differ in their shape. Arabica beans tend to be flatter and longer with a split that often has a slight curve, while Robusta is shorter and rounder with a straight split. The growing conditions for the two plants are also very different. Arabica beans require a very specific altitude and rain amount for growth, 2000-7200 ft (600-2200 m) and 47-87 inches (1200-2200 mm) of rain, while Robusta grows much lower at 0-2600 ft. (0-800 m) and needs much more water, 87-118 inches (2200-3000 mm) of rain for healthy growth. The temperatures required also vary greatly, 59-75 F (15-24 C) for Arabica and 64-97 F (18-36 C) for Robusta, making Robusta a thirstier plant but also much more heat tolerant. Arabica plants are shorter than Robusta too, 8.25-15 ft. (2.5-4.5 m) vs 15-25ft. (4.5-6.5 m) Despite these differences they both grow in the tropical to sub-tropical regions around the world that have the required elevation, temperature range, and average rainfall required for both types of beans.