Your lungs are on both sides of your chest. You have one lung on the right and one on the left, each sitting in its own compartment within the chest cavity. They flank the heart, which sits slightly left of center between them. While both lungs do the same job, they aren’t identical: your right lung is larger than your left, and the two differ in shape and structure.
Where Exactly Your Lungs Sit
Both lungs live inside the thoracic cavity, the space enclosed by your ribs, spine, and the muscles of your chest wall. The chest cavity is divided into three sections: a left pleural cavity, a right pleural cavity, and the mediastinum in the middle (where your heart, major blood vessels, and windpipe are housed). Each lung occupies its own pleural cavity.
Your lungs are bigger than most people realize. The top of each lung (called the apex) extends about 2 to 4 centimeters above your collarbone, reaching into the base of your neck. The bottom of each lung sits around the level of your sixth rib in the front of your chest, though they extend lower in the back. The diaphragm, the dome-shaped muscle you use to breathe, forms the floor beneath both lungs.
Each lung is wrapped in a double-layered membrane called the pleura. A thin layer of fluid between these two layers acts as a lubricant, letting the lungs glide smoothly against the chest wall every time you inhale and exhale. This fluid also creates a slight suction that helps the lungs stay expanded.
Why Your Right Lung Is Bigger
Your two lungs are not mirror images of each other. The right lung has three sections, called lobes: an upper, a middle, and a lower. The left lung has only two lobes: an upper and a lower. This size difference is entirely because of the heart.
Your heart sits slightly to the left of center in your chest. To make room for it, the left lung has a small indentation carved into its inner edge called the cardiac notch. This concavity sits around the level of the fourth rib and is where the heart and its protective sac rest without being covered by lung tissue. Because of this accommodation, the left lung is narrower and has less total volume than the right.
So while you have lungs on both sides, they’re deliberately unequal. The right lung handles a slightly larger share of your breathing capacity, and the left lung sacrifices some space to keep your heart protected and in position.
How Doctors Check Both Lungs
When a doctor listens to your lungs with a stethoscope, they check multiple points on both the front and back of your chest. The process typically starts at the top of your lungs and works downward, alternating between the right and left sides to compare the sounds from each lung. After listening from the front, they move to your back and repeat the pattern.
There’s a small triangle-shaped area on your back, between the shoulder blade and two large back muscles, where lung sounds come through especially clearly. When you cross your arms and lean forward, the muscles thin out over this spot, giving the stethoscope a cleaner signal. This is one reason doctors ask you to sit up, lean forward, and breathe deeply through your mouth during a chest exam.
When Lungs Are on the Opposite Side
In a rare condition called situs inversus, all the major organs in the chest and abdomen are flipped to the opposite side, like a mirror reflection of normal anatomy. This means the three-lobed lung ends up on the left and the two-lobed lung on the right, with the heart shifted to the right side of the chest as well. Situs inversus occurs in roughly 1 in every 10,000 people. Most people with this condition live completely normal lives and may not even know their organs are reversed until an imaging scan reveals it.
What Each Side Feels Like From the Outside
You can get a rough sense of where your lungs are by placing your hands on your chest. Your lungs fill most of the space behind your ribcage on both sides, from just above the collarbones down to the lower ribs. Pain or tightness on either side of the chest can involve the lung on that side, though the ribs, muscles, and pleura in the area can also be sources of discomfort.
Because the right lung is larger and has three lobes, conditions that affect one lobe (like pneumonia or a collapsed section) can sometimes be isolated to the right or left side, producing symptoms that feel one-sided. This is also why imaging like a chest X-ray always captures both lungs separately, letting doctors pinpoint which side and which lobe is affected.