Concave vs Convex | Meaning & Examples
Concave describes something as curved inward, like the inner surface of a bowl (i.e., the part that holds the food). Convex describes something as curved outward, like the outer surface of a bowl (i.e., the part that touches the surface of a table).
The valleys of the Grand Canyon can be described as “concave,” whereas the Rocky Mountains can be described as “convex.”
Although “concave” and “convex” can be used to describe the appearance of various things, these words are most commonly associated with lenses, mirrors, and reflections.
| Concave examples | Convex examples |
| An hourglass | An American football |
| The opening of a megaphone | An egg |
| The inner surface of a spoon | The outer surface of a helmet |
Concave meaning
“Concave” is an adjective that means “curved or hollowed inward.” This word is sometimes used to describe the characteristics of certain surfaces, but typically refers to the way light passes through or reflects off things like mirrors, lenses, and glass. For example, binoculars and telescopes are often made using concave lenses.
You can remember what “concave” means because it includes the word “cave,” which suggests an inward curve like that of a cave.
Concert halls typically incorporate concave elements to improve the acoustics.
My little sister inhaled deeply and sucked in her stomach, giving it a concave appearance.
Nesting dolls have concave features that allow them to be stored neatly inside one another.
“Concavity” is another noun form of this word and refers to something with concave qualities (e.g., “We came across a concavity on the side of the mountain”).
Concave examples
A few examples of things that can be described as “concave” include:
- Funnels
- The inner part of satellite dishes
- The inner part of a nest, where birds lay their eggs
- The inner surface of contact lenses, which are made to fit over the cornea of an eye
- The inside of a carved out pumpkin
Convex meaning
“Convex” is an adjective that means “curved or protruding outwards.”
Like “concave,” “convex” can describe the physical appearance of everyday objects but is typically associated with the way light interacts with the surfaces of mirrors, lenses, and glass. For example, magnifying glasses and fish-eye lenses use convex glass to enlarge the appearance of objects.
We turned the bowl upside down, using the convex side to display fruits on the table.
The convex lens of the projector uses light to produce a clear image on the screen.
The Christmas ornament’s convex shape reflected the sparkling lights beautifully.
Basketballs require immaculate convex contours for consistent and predictable dribbling.
Convex examples
A few examples of things that can be described as “convex” include:
- A round lollipop
- Certain door knobs
- Marbles
- The outer surface of a dome
- The outer surface of a spoon
Frequently asked questions about concave vs convex
- Is a bowl concave or convex?
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A bowl is both concave and convex, depending on which part you’re looking at.
The part that holds the food is concave, which means it curves inward. The outer part of the bowl that is placed on surfaces is convex, which means it curves outward.
- How do you know if something is concave or convex?
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Something is described as concave if it curves inward, like the part of the spoon that holds food. Conversely, something that curves outward is described as convex, like the other part of a spoon.
- What is a convex mirror?
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A convex mirror curves outward, which results in a wider, more magnified view. Convex mirrors are commonly used in car side-view mirrors and security cameras.
