Many college students spend long hours studying the complex branch of mathematics known as calculus. Calculus focuses on the processes of differentiation and integration. However, many are uncertain what calculus is used for in real life. Fortunately for those toiling away with their textbooks, calculus has a variety of important practical uses in fields such as economics, biology, astronomy and engineering.

### Calculus and Economics

Calculus is routinely used in economics. For example, economists use calculus to determine the right time to buy or sell something, the marginal value of a particular action, how much the price of an item affects how many people buy it, or any other instance that requires measuring change over time in two or more related variables.

### Calculus and Biology

Calculus is also used in biology. Some applications include modelling enzyme reactions as a function of nutrient concentration and the growth rate for bacteria, modelling population growth of a certain species, and modelling the relationship between related physical traits, such as backbone length and skull length.

### Calculus and Astronomy

Calculus has been used in astronomy since the 17th century to calculate the orbits of the planets around stars. Calculus is also necessary to accurately calculate the variable speed of moving objects in space, including asteroids, comets and other celestial bodies. Many of today's most interesting astronomical insights were gained with the use of calculus.

### Calculus and Engineering

Engineering is the field in which calculus is used most often in a real-world context. Calculus is necessary to determine distances with precision, such as the length of a cable supported by two poles. Calculus is also required by engineers and architects to calculate the size of curved or dome-style surfaces. Without the accuracy afforded by the use of calculus, bridges, roads and tunnels would not be as safe as they are today.

### Calculus and Other Fields

Calculus is also used indirectly in a number of other fields, including public policy, applied physics, computer science, graphic arts and more. All those hours in the classroom may have seemed pointless, but in reality calculus is all around us in many surprising ways.