Left vs Right Lung: Why They Are Different Sizes
Your two lungs are not twins. The right lung has three lobes and is a little bigger. The left lung has only two lobes and a dip in its side, called the cardiac notch, to make room for the heart.
Left vs right lung at a glance
| Left lung | Right lung | |
|---|---|---|
| Lobes | 2: upper and lower | 3: upper, middle and lower |
| Size | A little smaller | A little bigger, about 55% of total lung capacity |
| Shape | Longer and narrower, with a notch for the heart | Shorter and wider, sitting above the liver |
| Main airway | Longer and narrower | Shorter, wider and more upright |
| Special part | The lingula, a tongue-shaped flap | The middle lobe |
Making room for the heart
The heart sits slightly to the left in the chest. So the left lung has a dent in its front edge, the cardiac notch, and one fewer lobe. The right lung has its own squeeze: the liver lies just below it, pushing it up, which makes it shorter but wider.
Why things go down the right side
The right main bronchus, the airway into the right lung, is wider, shorter and runs more straight down than the left one. That is why an inhaled peanut or small object is more likely to end up in the right lung.
Quick facts
- Together the lungs hold hundreds of millions of tiny air sacs, called alveoli.
- Spread out, the inner surface of the lungs would cover a large part of a tennis court.
- You breathe around 20,000 times a day.
- Your lungs have no muscles of their own: the diaphragm and rib muscles do the work.
- Each lobe has its own airway and blood supply, so surgeons can remove one lobe on its own.
See it in 3D
Left vs right lung questions
Why does the left lung have two lobes?
To make room for the heart, which sits slightly to the left of the chest.
Which lung is bigger?
The right lung, which holds a little more than half of the total air.
How many lobes does the right lung have?
Three: upper, middle and lower.
What is the cardiac notch?
A dip in the front edge of the left lung where the heart sits.
Why do inhaled objects go into the right lung?
The right main airway is wider, shorter and more upright than the left.
More face-offs: see all 3D comparisons.
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