Side vs. Curtain Airbags: What’s the Difference?

Side airbags typically deploy from the seat or door to protect the torso (and sometimes the pelvis and head) in a side impact, while curtain airbags deploy from the roof rail like a curtain to shield occupants’ heads along the side windows and help prevent ejection, including during rollovers. Understanding how they differ in location, coverage, and crash scenarios can help you evaluate a vehicle’s overall side-impact and rollover protection strategy.

Key Differences at a Glance

The following points outline how side and curtain airbags differ in placement, purpose, and performance characteristics across common crash scenarios.

• Location: Side (thorax/pelvis) airbags are usually built into the outboard seatbacks or door panels; curtain airbags are housed in the roof rail above the side windows.
• Area protected: Side airbags primarily protect the chest and ribs, sometimes the pelvis or head (in combo designs); curtain airbags primarily protect the head along the side glass from the A- to C- or D-pillars.
• Crash scenarios: Side airbags address near-side impacts where door intrusion threatens the torso; curtain airbags address both side impacts and rollovers by covering windows and helping prevent partial or full ejection.
• Inflation profile: Side thorax airbags deploy rapidly and typically deflate quickly; curtain airbags often stay inflated longer to offer rollover protection and ejection mitigation.
• Occupant coverage: Side airbags are most common for front seats, with rear-seat torso airbags less common but growing; curtain airbags usually extend over multiple rows.
• Regulatory role: Curtain airbags are commonly used to meet ejection-mitigation rules (such as FMVSS 226 in the U.S.); side airbags help vehicles achieve strong side-impact ratings (e.g., IIHS, NHTSA).

Together, side and curtain airbags work as a system: the side airbag cushions the torso against intrusion, while the curtain airbag shields the head and helps keep occupants inside the vehicle.

Where They’re Installed and How They Deploy

Side (Thorax/Pelvis) Airbags

Side airbags typically live in the seatback’s outboard bolster or, less commonly, in the door panel. Sensors in the B-pillar, door, or seat detect a side impact via acceleration and pressure changes, firing the bag to form a cushion between the occupant’s torso and the intruding door structure. Some designs add a lower chamber to protect the pelvis, which is particularly vulnerable when struck by bumper beams or armrests.

Curtain (Head) Airbags

Curtain airbags are packaged in the roof rail and deploy downward like a drape, covering the side window area from front to rear seats. Tethers keep the inflated curtain positioned against the glass, and many systems are engineered to remain inflated for several seconds—long enough to address multi-event crashes and rollovers. In rollovers, curtains reduce the risk of partial ejection and help keep occupants away from shattered glass and external hazards.

Protection Use Cases

These examples illustrate when each airbag type provides the most benefit and how the two complement one another.

• Near-side T-bone crash: The side airbag cushions the chest and pelvis from door intrusion; the curtain airbag protects the head from striking the window, B-pillar, or intruding object.
• Oblique side impact: The side airbag mitigates rib and internal-organ injuries; the curtain reduces head accelerations and laceration risk from broken glass.
• Rollover: Curtain airbags help keep heads inside and reduce ejection risk; side thorax airbags are less central here, though some head/torso combo bags assist if they remain inflated.
• Far-side impacts (opposite side of the occupant): Curtain airbags can still protect the head; some vehicles now add center airbags to reduce occupant-to-occupant and interior contact.

When combined, these technologies significantly lower the risk of serious head and chest injury across a range of side-impact and rollover crashes.

Standards, Ratings, and Real-World Context

In the U.S., many automakers use curtain airbags to help meet FMVSS 226 ejection-mitigation requirements, which has made multi-row curtains common. The Insurance Institute for Highway Safety (IIHS) updated its side-impact test in 2021 with a heavier, faster barrier to better reflect modern crash forces; strong performance typically requires both effective torso airbags and robust curtain coverage. NHTSA’s side-impact and pole tests also reward comprehensive side and head protection. Globally, programs like Euro NCAP and ANCAP similarly evaluate head and thorax protection in side impacts and poles, pressuring manufacturers to include both systems across more seating rows.

Variations You May See

Automakers offer different side-impact restraint designs. The list below explains common variants and what they’re meant to address.

• Thorax-only side airbags: Focus on ribcage and internal-organ protection in front seats.
• Thorax–pelvis side airbags: Add lower-chamber coverage for hip and pelvic injuries.
• Head–thorax combo side airbags: Larger seat-mounted bags that extend upward to protect the head when a full curtain isn’t present.
• Inflatable curtain with extended coverage: Spans A- through C- or D-pillars, often covering third rows in SUVs; designed to stay inflated for rollover events.
• Rear-seat side airbags: Increasingly available to protect back-seat occupants’ torsos; curtains often already protect their heads.
• Front center airbags: Deploy between the front seats to reduce far-side head and torso contact and occupant-to-occupant impacts.

Knowing which combination a vehicle uses helps you assess coverage in every seat and crash mode, particularly if you frequently carry rear passengers.

Buying and Ownership Tips

Use the pointers below to evaluate a vehicle’s side-impact safety and to avoid compromising your airbag systems in everyday use.

• Look for both: Prioritize vehicles with side thorax airbags for all front seats and curtain airbags covering all seating rows.
• Check ratings: Review IIHS side and updated side-impact scores and NHTSA side/pole ratings for your specific trim and seating configuration.
• Confirm ejection mitigation: Ensure the curtain system provides rollover coverage and meets ejection-mitigation requirements.
• Mind seat covers: Avoid aftermarket seat covers on seats with built-in airbags unless they’re explicitly airbag-compatible.
• Child seats: It’s generally safe to install child seats next to side/curtain airbags; follow your vehicle and seat manuals, keep children properly restrained, and avoid pressing seats against door modules.
• Positioning: Encourage passengers not to lean against windows; proper seating posture improves airbag effectiveness.
• Used cars: Verify recalls and that all original airbags are intact; mismatched trim or unknown crash history can hide missing or counterfeit components.

These steps help ensure the airbags you paid for deliver their intended protection when it matters most.

Maintenance and After a Crash

Airbags are not maintenance items, but the airbag warning light should illuminate briefly at start-up and then turn off; if it stays on, have the system inspected. After any deployment, modules, sensors, seatbelts with pretensioners, and control units may require replacement. Stay current on recall campaigns—many older Takata inflators have been replaced, and additional service actions can arise. Always use OEM procedures and parts for repairs affecting airbag-equipped seats, doors, pillars, and roof rails.

Bottom Line

Side airbags concentrate on protecting the torso (and sometimes pelvis/head) from door intrusion in a side impact, while curtain airbags focus on head protection along the windows and preventing ejection, especially in rollovers. Together, they form a complementary shield that modern crash tests and regulations increasingly expect across all seating rows.

Summary

Side airbags are typically seat- or door-mounted cushions for the chest and pelvis during side impacts; curtain airbags are roof-rail-deployed drapes that protect heads and mitigate ejection in both side impacts and rollovers. Look for vehicles that provide both across all rows, verify ratings, avoid compromising components with aftermarket seat covers, and follow maintenance and recall guidance to preserve full protective capability.

What are the two types of air bags?

Vehicles can be equipped with both front and side air bags. Frontal air bags have been standard equipment in all passenger vehicles since the late 1990s. Side air bags are being offered as standard or optional equipment on many new passenger vehicles.

Are curtain airbags the same as side airbags?

Rear-window curtain airbags are designed to protect people in back seats in rear-end crashes. Far-side airbags keep drivers and front-seat passengers from hitting each other in a crash. Inflatable safety belts are aimed at reducing rear-seat chest injuries.

What is the purpose of the curtain airbags?

Curtain airbags protect occupants’ heads from side-impact collisions and rollover accidents by deploying from the roofline above the windows to cushion impact with the vehicle’s frame or window, while also helping to prevent ejection from the vehicle. They are a crucial safety feature that reduces head and neck injuries in side crashes and are designed to remain inflated longer than other airbags to provide continuous protection through multiple vehicle rolls.
 
How they work:

• Deployment: In a side-impact or rollover crash, sensors trigger the airbags to deploy from the roof rails, covering the area between the roof and the windows. 
• Cushioning: The inflated curtain creates a protective cushion between the occupants’ heads and the vehicle’s side structure, including windows and door frames. 
• Ejection prevention: The curtain helps to keep occupants inside the vehicle during a rollover or severe side impact, preventing them from being partially or fully ejected through the windows. 

Key benefits:

• Reduced fatalities and injuries: Studies show a substantial reduction in fatalities and head and neck injuries in vehicles equipped with side curtain airbags. 
• Protection in rollovers: Sensors activate them during rollovers to keep passengers contained within the vehicle and away from the roof. 
• Extended inflation: They are designed to stay inflated for longer periods, potentially up to several seconds or even minutes, to provide continued protection through multiple vehicle rolls. 

Proper use: 

• Seatbelts are essential: For best protection, occupants must wear their seatbelts properly.
• Upright posture: Occupants should sit upright and well back in their seats.
• Avoid interference: Do not attach objects to the side windows or roof pillars, as they can interfere with the airbags’ proper operation.

How to tell if a car has side curtain airbags?

They will be marked on the seat, and if your car has side curtain airbags, there will be a marking on the side of the car near the roof.