Lung Volumes and Capacities: TV, IRV, ERV & RV Explained (Chart)

Pulmonary volumes and capacities describe how much air your lungs hold at different points in the breathing cycle. There are four basic volumes — tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV) and residual volume (RV) — and four capacities, which are simply two or more of those volumes added together: inspiratory capacity (IC), functional residual capacity (FRC), vital capacity (VC) and total lung capacity (TLC).

In a healthy young adult man, a quiet breath moves about 500 mL of air (TV). You can breathe in roughly another 3,000 mL on top of that (IRV), push out about 1,100 mL more after a normal exhale (ERV), and around 1,200 mL always stays behind (RV). Add all four together and you get a total lung capacity of close to 6 liters.

That’s the short version. Below, we’ll walk through each volume and capacity one at a time, show you a labeled chart, give you a quick matching exercise, and explain what these numbers actually mean when a doctor orders a lung function test.

What Are Pulmonary Volumes and Capacities?

Think of your lungs as a balloon that is never fully empty. Every breath you take fills and partly empties that balloon, but the amount of air inside changes depending on whether you’re resting, sighing, blowing out birthday candles or taking the deepest breath you can.

Physiologists divide that air into layers. The four volumes are separate, non-overlapping layers — they never share any air. The four capacities are combinations of those layers. A simple rule makes this easier to remember: a capacity always contains two or more volumes.

These measurements are not just textbook trivia. They’re the foundation of pulmonary function testing (PFTs), the set of breathing tests used to diagnose asthma, COPD, pulmonary fibrosis and many other conditions. If you want a broader picture of how air reaches the bloodstream in the first place, our guide on how the pulmonary system works is a good place to start.

Pulmonary Lung Volumes and Capacities Chart (Normal Values)

The table below summarizes the pulmonary lung volumes and capacities you’ll see on most charts. Values are typical averages for healthy adults; your own numbers depend on age, sex, height, body size and ethnicity, so labs always compare you to predicted values rather than to a fixed number.

Measurement	Abbreviation	Type	What it includes	Typical adult male	Typical adult female
Tidal volume	TV (VT)	Volume	Air in and out with a quiet breath	~500 mL	~500 mL
Inspiratory reserve volume	IRV	Volume	Extra air you can inhale after a normal breath in	~3,000 mL	~1,900 mL
Expiratory reserve volume	ERV	Volume	Extra air you can exhale after a normal breath out	~1,100 mL	~700 mL
Residual volume	RV	Volume	Air left after the hardest possible exhale	~1,200 mL	~1,100 mL
Inspiratory capacity	IC	Capacity	TV + IRV	~3,500 mL	~2,400 mL
Functional residual capacity	FRC	Capacity	ERV + RV	~2,300 mL	~1,800 mL
Vital capacity	VC	Capacity	IRV + TV + ERV	~4,600 mL	~3,100 mL
Total lung capacity	TLC	Capacity	IRV + TV + ERV + RV	~5,800–6,000 mL	~4,200 mL

According to StatPearls, the average total lung capacity in healthy adults is about 6 liters, and it rises quickly through childhood before plateauing around age 25 (NIH StatPearls: Physiology, Lung Capacity).

The Four Lung Volumes Explained

Tidal Volume (TV)

Tidal volume is the amount of air that moves in or out of your lungs during a normal, relaxed breath. It’s the breathing you’re doing right now while reading this — about 500 mL, or roughly 6–8 mL per kilogram of ideal body weight.

Not all of that 500 mL reaches the air sacs. About 150 mL stays in the nose, throat, trachea and bronchi, where no gas exchange happens. This is called anatomical dead space. The rest travels down to the alveoli, where oxygen crosses into the blood — a process we explain step by step in our article on gas exchange between the alveoli and pulmonary capillaries.

Tidal volume matters a great deal in intensive care. When patients are on a ventilator, clinicians set the tidal volume carefully, because pushing too much air with each breath can injure the lungs.

Inspiratory Reserve Volume (IRV)

Inspiratory reserve volume is the extra air you can breathe in after a normal inhalation. Take a normal breath in, pause, then keep inhaling as hard as you can — that additional air is your IRV, roughly 3,000 mL in an average man and about 1,900 mL in an average woman.

IRV is your body’s built-in reserve for exercise. When you start running up stairs, your tidal volume grows by borrowing from the IRV, letting you move much more air with each breath without changing how fast you breathe.

Expiratory Reserve Volume (ERV)

Expiratory reserve volume is the extra air you can forcefully blow out after a normal exhalation. Breathe out normally, then squeeze out everything you can using your abdominal and chest muscles — that’s your ERV, typically about 1,100 mL in men and 700 mL in women.

ERV is one of the first measurements to shrink with obesity. Weight around the abdomen pushes the diaphragm upward, so you start each breath closer to the bottom of your lungs. StatPearls notes that as body mass index climbs, ERV and FRC fall noticeably, sometimes to the point where FRC nearly equals residual volume (NIH StatPearls: Physiology, Residual Volume).

Residual Volume (RV)

Residual volume is the air that stays in your lungs even after you exhale as hard as you possibly can. Reference values are roughly 1 to 1.2 liters. You cannot blow this air out, no matter how hard you try.

Why does it stay? As you force air out, pressure around the smallest airways rises until they collapse and trap the air behind them. That trapped air is actually useful: it keeps the alveoli from collapsing completely and allows gas exchange to continue between breaths. A thin film of pulmonary surfactant helps too, by lowering surface tension so the tiny air sacs don’t stick shut.

Here’s the key practical point: spirometry cannot measure residual volume. Because RV never leaves the lungs, a device that only measures air flowing in and out can’t see it. It has to be measured indirectly (more on that below).

The Four Lung Capacities Explained

Inspiratory Capacity (IC)

IC = TV + IRV. Inspiratory capacity is the maximum amount of air you can breathe in starting from the end of a normal, relaxed exhale. In an average adult man it’s about 3,500 mL.

In COPD, IC is a useful marker of air trapping. As the lungs become overinflated, people start each breath with more air already inside, which leaves less room to breathe in. An IC-to-TLC ratio below 25% has been linked to more hospital admissions and higher mortality in COPD patients.

Functional Residual Capacity (FRC)

FRC = ERV + RV. Functional residual capacity is the air left in your lungs at the end of a normal, quiet exhale — about 2,300 mL in an average man.

FRC is the lungs’ natural resting point. At this volume, the inward pull of the elastic lung tissue is exactly balanced by the outward spring of the chest wall. It also acts as an oxygen buffer: because the lungs never empty between breaths, oxygen levels in the blood stay steady from one breath to the next instead of rising and falling with every inhale. That steady supply feeds the pulmonary circulation, which picks up oxygen continuously, not in pulses.

FRC is also the starting point for measuring residual volume. Labs measure FRC first, then subtract ERV to calculate RV.

Vital Capacity (VC)

VC = IRV + TV + ERV. Vital capacity is the largest amount of air you can move in a single breath — from the deepest inhale to the most complete exhale. In an average man it’s about 4,600 mL.

When the breath out is done as fast and hard as possible, it’s called forced vital capacity (FVC), one of the two main numbers on a spirometry report. The other is FEV1, the volume blown out in the first second. The FEV1/FVC ratio is what separates obstructive from restrictive patterns.

Total Lung Capacity (TLC)

TLC = IRV + TV + ERV + RV (or simply VC + RV). Total lung capacity is all the air your lungs hold after the biggest breath in you can take — about 6 liters in a healthy adult man and a little over 4 liters in a woman.

TLC is the single most important number for diagnosing a restrictive lung problem. Because it includes residual volume, it also can’t be measured with spirometry alone.

Quick Formulas to Remember

If you’re studying for an exam, these five equations cover almost everything:

• IC = TV + IRV
• FRC = ERV + RV
• VC = IRV + TV + ERV
• TLC = VC + RV
• TLC = IC + FRC

A handy memory trick: any measurement with “residual” in its name (RV, FRC) or that includes the whole lung (TLC) contains air you can’t breathe out — so none of those three can be measured by a spirometer.

Match the Pulmonary Volume With Its Definition

This is one of the most common exam and homework questions in respiratory physiology. Try to match each pulmonary volume with its definition before you look at the answers below.

#	Volume or capacity		Letter	Definition
1	Tidal volume		A	Air remaining after a maximal forced exhale
2	Inspiratory reserve volume		B	Air left in the lungs after a normal, quiet exhale
3	Expiratory reserve volume		C	Air moved in or out with a normal resting breath
4	Residual volume		D	Maximum air exhaled after a maximal inhale
5	Functional residual capacity		E	Extra air that can be inhaled after a normal inhale
6	Vital capacity		F	Extra air that can be exhaled after a normal exhale
7	Total lung capacity		G	All the air in the lungs after a maximal inhale

Answers: 1–C, 2–E, 3–F, 4–A, 5–B, 6–D, 7–G.

The most common mix-up is between residual volume and functional residual capacity. Remember: RV is what’s left after you blow out everything; FRC is what’s left after a normal breath out. FRC is bigger, because it also contains the expiratory reserve volume.

The second most common mix-up is ERV versus RV. ERV is the air you can still push out after a normal exhale. RV is the air you can’t push out at all.

How Lung Volumes Are Measured

Doctors use two main types of tests:

Test	What it measures	What it can’t measure
Spirometry	TV, IRV, ERV, IC, VC, FVC, FEV1	RV, FRC, TLC
Body plethysmography	FRC (then RV and TLC), airway resistance	—
Helium dilution	FRC (then RV and TLC)	Air in poorly ventilated areas
Nitrogen washout	FRC (then RV and TLC)	Air in poorly ventilated areas
CT-based volumetry	TLC from chest images	Not routine; involves radiation

Body plethysmography is considered the gold standard. You sit inside a sealed, see-through booth and breathe or pant through a mouthpiece. Using Boyle’s law, the machine converts tiny pressure changes in the booth into lung volumes. The test is painless, usually takes about 15 minutes, and measures total lung capacity, functional residual capacity and residual volume — things spirometry simply can’t see (Cleveland Clinic: Body Plethysmography).

Gas dilution methods (helium dilution and nitrogen washout) are simpler but can underestimate lung volumes in people with severe airflow obstruction, because the test gas doesn’t reach trapped, poorly ventilated pockets of lung.

If you’re scheduled for testing, a lung function lab or a pulmonary practice such as the Central Florida pulmonary group will usually perform spirometry first and add lung volumes when the results need clarification.

Obstructive vs Restrictive Patterns

Pulmonary volumes and capacities really earn their keep when something goes wrong. The two big patterns look almost like mirror images.

Measurement	Obstructive disease (COPD, asthma, emphysema)	Restrictive disease (fibrosis, obesity, chest wall or neuromuscular disease)
TLC	Normal or increased	Decreased (below the 5th percentile defines restriction)
RV	Increased (air trapping)	Decreased or normal
FRC	Increased	Decreased
VC / FVC	Normal or decreased	Decreased
RV/TLC ratio	Increased	Normal or increased
FEV1/FVC	Low	Normal or high

Obstructive Lung Disease

In COPD, asthma and emphysema, the airways narrow and collapse early during exhalation. Air gets trapped behind them, so residual volume climbs — often before any other number changes. Over time the lungs become hyperinflated, raising FRC and sometimes TLC. An RV/TLC ratio above about 40% signals resting hyperinflation and is an independent risk factor for death in COPD.

People living with these conditions often benefit from specialist care; if you’re in the southern US, our list of COPD specialists in Alabama may help.

Restrictive Lung Disease

In restrictive disease, the lungs can’t expand fully — either because the lung tissue itself is stiff (pulmonary fibrosis, sarcoidosis) or because something outside the lungs limits them (obesity, kyphoscoliosis, ALS, myasthenia gravis). According to ATS/ERS criteria, restriction is defined by a TLC below the 5th percentile of predicted with a normal FEV1/VC ratio. TLC, FRC and RV all shrink together.

Chronic low oxygen from either pattern can also affect the blood vessels of the lungs. Low alveolar oxygen makes pulmonary arteries tighten — a reflex described in our article on hypoxia and pulmonary vasoconstriction. Over years, this can raise pressure in the pulmonary artery and veins and lead to group 3 pulmonary hypertension, the type caused by lung disease and hypoxia.

Why These Numbers Matter in Real Life

Pulmonary function tests that include lung volumes are ordered for many reasons:

• Unexplained shortness of breath — to tell whether the problem is airflow, lung size or gas transfer.
• Confirming restriction — spirometry can suggest restriction, but only a measured TLC can confirm it.
• Tracking chronic disease — watching RV and FRC rise in COPD, or TLC fall in fibrosis.
• Before surgery — especially lung resection, to estimate how much reserve remains.
• Pulmonary hypertension workups — lung volumes help rule out lung disease as a cause; PFTs are a routine part of how pulmonary hypertension is diagnosed and of the steps used to diagnose pulmonary arterial hypertension specifically.

Remember that lungs and heart work as one system. The oxygen your lung volumes bring in only helps if it’s carried around the body, which is why the pulmonary and systemic circulation are always considered together. If your results are abnormal, a lung specialist — for example one of the pulmonologists in Alabama we’ve profiled — can interpret them in the context of your symptoms.

What Affects Your Lung Volumes?

Your predicted values are calculated from several factors:

• Age: TLC stays fairly stable in adulthood, but RV rises and VC falls as lung tissue loses elasticity with age.
• Sex: Men generally have larger lung volumes than women of the same height.
• Height: Taller people have bigger chests and larger lungs.
• Body composition: Abdominal weight lowers ERV and FRC.
• Ethnicity: Reference equations account for population differences; modern labs increasingly use Global Lung Function Initiative (GLI) equations.
• Position: FRC is smaller lying down than sitting or standing, because abdominal contents push the diaphragm up.
• Fitness and altitude: Training improves how efficiently you use your volumes; people raised at high altitude may have slightly larger lungs.

Rather than a single “normal” number, results are usually reported as a percentage of predicted or as a z-score, with values below the lower limit of normal considered abnormal.

Frequently Asked Questions

What are the 4 pulmonary volumes and capacities?

The four volumes are tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV) and residual volume (RV). The four capacities are inspiratory capacity (IC), functional residual capacity (FRC), vital capacity (VC) and total lung capacity (TLC). Each capacity is the sum of two or more volumes.

What is the difference between a lung volume and a lung capacity?

A lung volume is a single, non-overlapping layer of air, such as tidal volume. A lung capacity is the sum of two or more volumes. For example, vital capacity combines IRV, TV and ERV.

What is a normal tidal volume?

A normal resting tidal volume in adults is about 500 mL, or roughly 6–8 mL per kilogram of ideal body weight. About 150 mL of that stays in the airways as dead space and doesn’t take part in gas exchange.

Why can’t spirometry measure residual volume?

Spirometry only measures air that moves in and out of your mouth. Residual volume never leaves the lungs, so it’s invisible to a spirometer. RV, FRC and TLC must be measured with body plethysmography, gas dilution, nitrogen washout or imaging.

Is functional residual capacity the same as residual volume?

No. Residual volume is the air left after a maximal exhale. Functional residual capacity is the air left after a normal exhale, and it equals residual volume plus expiratory reserve volume — so FRC is always larger.

What happens to lung volumes in COPD?

COPD causes air trapping, so residual volume rises first, followed by FRC and often TLC. Inspiratory capacity falls because the lungs are already partly full at rest. An RV/TLC ratio above about 40% points to hyperinflation.

How do pulmonary volumes and capacities change in restrictive lung disease?

In restrictive disease, total lung capacity, functional residual capacity and residual volume all decrease, because the lungs or chest wall can’t expand normally. A TLC below the 5th percentile of predicted, with a normal FEV1/VC ratio, confirms restriction.

What is a normal total lung capacity?

In a healthy adult man, total lung capacity is about 6 liters; in women it is typically around 4–4.5 liters. Your own normal range depends on age, sex, height and ethnicity, so results are compared with predicted values.

Bottom Line

Pulmonary volumes and capacities break the air in your lungs into four basic layers — TV, IRV, ERV and RV — and four combinations of those layers — IC, FRC, VC and TLC. A healthy adult moves about half a liter with each quiet breath, keeps more than a liter permanently in reserve, and holds around 6 liters at full inflation. Spirometry measures the air you can move; body plethysmography or gas methods are needed for the air that stays behind. When these numbers shift, they point clearly toward either an obstructive problem (air trapping, high RV) or a restrictive one (small lungs, low TLC), which is why they sit at the heart of every lung function test.

Medical disclaimer: This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Always talk to your doctor or a qualified lung specialist about your own test results and symptoms.