# Turbulence levels explained: light, moderate, severe and extreme

**Short answer:** Pilots rate turbulence on four levels: light, moderate, severe and extreme. Light causes a slight strain against your seat belt; moderate makes walking and food service difficult; severe throws loose objects about and is rare; extreme is rarer still. In g, moderate means changes of about 0.5 to 1.0 g at the airplane's center of gravity, while airliners are built to carry at least 2.5 g.

## Key facts
- The FAA's turbulence scale has four levels, light, moderate, severe and extreme, judged by how the aircraft and the people inside react [1].
- WMO guidance puts moderate turbulence at accelerometer changes of 0.5 to 1.0 g at the aircraft's center of gravity, and severe at more than 1.0 g [2].
- On ICAO's objective scale (EDR), light is above 0.10, moderate is 0.20 to below 0.45, and severe is 0.45 or more, for a medium-sized transport aircraft [3].
- US turbulence forecasts call it severe at EDR 0.54 for heavy aircraft (over 300,000 lb), versus 0.44 for medium aircraft [4].
- Airliners must carry at least +2.5 g and −1.0 g without damage, with a safety factor of 1.5 on top [5][6].
- In 111 US airline turbulence accidents from 2009 to 2018, the reported intensity was severe in 44.1%, moderate in 41.4% and light in 0.9% [1].

## What "g" means on an airplane
A g is a unit of acceleration equal to normal gravity. Sitting still on the ground, or flying level in smooth air, you feel 1 g: your normal weight.

A bump changes that number for a moment. If the airplane rises sharply, you're pressed into your seat and feel heavier, say 1.3 g. If it drops, you feel lighter, say 0.7 g. Turbulence is usually described by that change, written Δg ("delta g"): both of those examples are changes of 0.3 g.

Your body is very good at noticing small changes in g, which is why a bump that is tiny for the airplane can feel big in your stomach.

## The four turbulence levels
Pilots report turbulence using an FAA scale that describes both the aircraft and the cabin. The NTSB reproduces it in its 2021 turbulence study [1]. The g ranges come from WMO guidance [2], and the EDR values from ICAO's standard for a medium-sized transport aircraft [3].

| Level | What the aircraft does | What you feel in the cabin | Change in g (WMO) | EDR (ICAO) |
|---|---|---|---|---|
| **Light** | Slight, erratic changes in altitude or attitude | A slight strain against your seat belt; loose items may shift slightly; drinks service can continue; walking is easy | less than moderate | above 0.10, below 0.20 |
| **Moderate** | Changes in altitude or attitude, but the aircraft stays in positive control at all times | Definite strain against your seat belt; loose items are dislodged; walking and food service are difficult | 0.5 to 1.0 g | 0.20 to below 0.45 |
| **Severe** | Large, abrupt changes in altitude or attitude; may be momentarily out of control | You're forced hard against your seat belt; loose items are tossed about; walking is impossible | more than 1.0 g | 0.45 or more |
| **Extreme** | Violently tossed about, practically impossible to control | More pronounced than severe | not given | not given |

Two notes make this table less scary than it looks. First, these are reporting categories for pilots, written for every kind of aircraft, from small planes to jumbo jets. Second, extreme turbulence is so rare it doesn't appear in the NTSB's 10-year accident data at all: of the 111 US airline turbulence accidents studied, none was reported as extreme [1].

### Light chop vs. light turbulence
Pilots also use the word "chop." Chop is "slight, rapid, and somewhat rhythmic bumpiness without appreciable changes in altitude or attitude" [1]. Think of a car on a gravel road. Light and moderate turbulence can each be reported as chop instead, when the ride is jittery but the airplane isn't really moving up and down [1].

### Occasional, intermittent, continuous
Pilot reports may also say how often the bumps came [1]:

- **Occasional:** less than one third of the time.
- **Intermittent:** between one third and two thirds of the time.
- **Continuous:** more than two thirds of the time.

So "occasional light chop" is about the gentlest thing a pilot can report short of "smooth." You can read more about these reports in [what PIREPs and SIGMETs are](/guides/pilot-reports-and-sigmets).

## How strong is turbulence in g, compared with what planes can take?
This is where the numbers become reassuring. A bump of +0.5 g, already at the moderate end, takes the airplane from 1 g to 1.5 g. Here's what the airplane is built for:

| | Load factor |
|---|---|
| Normal flight | 1 g |
| A moderate bump of +0.5 g | 1.5 g |
| Limit load: no permanent deformation allowed [5][7] | at least +2.5 g and −1.0 g |
| Ultimate load: limit × 1.5, held for at least 3 seconds without failure [6][7] | at least +3.75 g |

On top of that, airliners are designed for sharp vertical gusts of 56 feet per second at sea level, tapering to 44 feet per second at 15,000 feet [8].

The most common turbulence on a typical flight, light bumps and chop, sits in the lowest part of this range. That's why light turbulence is a comfort issue rather than a safety one. The real risk in stronger turbulence is to people who aren't belted, which [is turbulence dangerous?](/guides/is-turbulence-dangerous) covers in detail.

## Why the same air feels different in different airplanes
Turbulence levels are partly about the airplane. The same patch of air bumps a small regional jet more than a big wide-body, much as the same waves rock a small boat more than a ferry; see [do bigger planes feel less turbulence?](/guides/do-bigger-planes-feel-less-turbulence)

To handle this, meteorologists use an aircraft-independent measure called the eddy dissipation rate (EDR). EDR describes the air itself, like a "sea state" that doesn't depend on the size of the ship [1]. It's the official turbulence intensity measure recognized by ICAO [1]. Our guide to [how turbulence is measured](/guides/how-is-turbulence-measured) compares EDR with g and pilot reports.

The thresholds then shift with aircraft size. The Aviation Weather Center's forecasts use these EDR values (shown ×100) [4]:

| Aircraft class | Light | Moderate | Severe |
|---|---|---|---|
| Light (under 15,500 lb) | 13 | 16 | 36 |
| Medium (15,500 to 300,000 lb) | 15 | 20 | 44 |
| Heavy (over 300,000 lb) | 17 | 24 | 54 |

In plain words: a heavy airliner needs noticeably rougher air before the ride becomes "severe" for it. ICAO notes the same thing about heavy aircraft [3]. This is one reason why [where you sit and what you fly](/guides/best-seat-for-turbulence) can change how a flight feels.

## How rare is severe turbulence?
Severe turbulence is uncommon, and forecasters work to keep flights away from it. For a sense of scale, a 2023 study found that at a typical point over the North Atlantic at cruising altitude, severe-or-greater clear-air turbulence was present for about 27.4 hours in 2020 [9]. That's roughly 0.3% of the year, in one of the world's busiest flight regions.

When severe turbulence is expected, weather offices issue warnings called SIGMETs so flights can be planned around it. A forecast for your flight should show severe only when such a warning exists; see [how turbulence forecasts work](/guides/turbulence-forecast).

## What each level means for you
- **Light:** totally normal on many flights. The seat belt sign may come on. Service often continues.
- **Moderate:** the crew may pause service and sit down. Keep your belt snug, put drinks on the tray, and breathe out slowly. Uncomfortable, but within what the airplane handles routinely.
- **Severe:** rare. Stay seated with your belt tight and follow every instruction from the crew.

## How Sorapuff helps
Sorapuff's bump meter, which works in airplane mode, measures each bump with your phone's motion sensors and shows it in g next to the 2.5 g the airplane is built for. After landing, your Bump Report counts the light, moderate and strong bumps and shows how much of that margin the biggest one used. It's free; see [pricing](/pricing). Your phone measures at your seat, not at the center of gravity, so treat readings as a guide.

## FAQ
### What does moderate turbulence feel like?
You feel a definite strain against your seat belt, loose items like cups or phones can move, and walking or serving food becomes difficult. The airplane changes altitude or attitude a little but stays in positive control at all times. In g, moderate turbulence means changes of roughly 0.5 to 1.0 g at the center of gravity. It's uncomfortable but well within the airplane's design limits.

### How many g is severe turbulence?
WMO guidance describes severe turbulence as accelerometer changes of more than 1.0 g at the aircraft's center of gravity. For comparison, airliners must carry at least 2.5 g without permanent deformation and 1.5 times that without failing. Severe turbulence is rare, and pilots plan around areas where it's forecast. The main risk in it is to unbelted people.

### What is the difference between light chop and light turbulence?
Light chop is rapid, somewhat rhythmic bumpiness without appreciable changes in altitude or attitude, like a car on gravel. Light turbulence means slight, erratic changes in altitude or attitude. In both, you may feel a slight strain against your belt, and food service usually continues. Pilots choose whichever word best describes what they felt.

### What is EDR in turbulence?
EDR, the eddy dissipation rate, is an objective measure of how turbulent the air itself is, independent of the aircraft. ICAO and WMO recognize it as the official turbulence intensity measure. For a medium-sized airliner, ICAO calls EDR from 0.20 moderate and from 0.45 severe. Many airliners compute EDR automatically, and forecast maps use it too.

### Can my phone measure turbulence?
Yes, roughly. Every phone has an accelerometer that senses changes in g. A phone at your seat feels the bumps you feel, which can differ a little from what the airplane's center of gravity feels, depending on where you sit. It won't match the airplane's own sensors exactly, but it's a good, honest picture of your ride.

## Sources
1. [Preventing Turbulence-Related Injuries in Air Carrier Operations Conducted Under Title 14 CFR Part 121, Safety Research Report SS-21/01 (2021), NTSB](https://www.ntsb.gov/safety/safety-studies/Documents/SS2101.pdf)
2. [Aviation Hazards: Turbulence and Wind Shear, World Meteorological Organization](https://community.wmo.int/node/36996)
3. [New 0.25 degree WAFS Hazard Data, training material (November 2020), ICAO](https://www.icao.int/sites/default/files/METP/Documents/Nov-2020-New-WAFS-Hazard-data-training-material.pdf)
4. [Graphical Forecasts for Aviation help: Turbulence, Aviation Weather Center (NOAA)](https://aviationweather.gov/gfa/help/?page=turb)
5. [14 CFR § 25.337, Limit maneuvering load factors, Legal Information Institute (Cornell Law School)](https://www.law.cornell.edu/cfr/text/14/25.337)
6. [14 CFR § 25.303, Factor of safety, Legal Information Institute (Cornell Law School)](https://www.law.cornell.edu/cfr/text/14/25.303)
7. [14 CFR § 25.305, Strength and deformation, Legal Information Institute (Cornell Law School)](https://www.law.cornell.edu/cfr/text/14/25.305)
8. [14 CFR § 25.341, Gust and turbulence loads, Legal Information Institute (Cornell Law School)](https://www.law.cornell.edu/cfr/text/14/25.341)
9. [Evidence for Large Increases in Clear-Air Turbulence Over the Past Four Decades, Geophysical Research Letters (2023)](https://doi.org/10.1029/2023GL103814)

Updated November 13, 2026 · https://sorapuff.app/guides/turbulence-levels

## Related guides

- [Is Turbulence Dangerous? What the Safety Data Says](https://sorapuff.app/guides/is-turbulence-dangerous): Turbulence is uncomfortable but rarely dangerous for a belted passenger. See the NTSB data, the 2.5 g airliners are built for, and how to stay safe.
- [How Is Turbulence Measured? g, EDR and Pilot Reports](https://sorapuff.app/guides/how-is-turbulence-measured): How is turbulence measured? In g by accelerometers, as EDR by airliners' own computers, and by pilots' reports. Plus how a phone's sensors can measure bumps.
- [How Far Does a Plane Drop in Turbulence? Feet vs. g](https://sorapuff.app/guides/how-far-does-a-plane-drop-in-turbulence): How far does a plane drop in turbulence? Usually a few feet. What flight data shows, why a small drop feels huge, and why the 1,000-foot drop is mostly a myth.
- [What Is a PIREP? What Is a SIGMET? Explained Simply](https://sorapuff.app/guides/pilot-reports-and-sigmets): A PIREP is a pilot's report of the weather met in flight; a SIGMET is an official hazard warning. Learn to read both and what they mean for your flight.