The new GMC Sierra 1500 continues to define the full-size pickup truck category with a spacious, well-appointed interior across its lineup. Whether you require a functional work truck or a premium pickup with all the amenities, the Sierra 1500 delivers interior dimensions that prioritize passenger comfort and practical functionality.

Cab Configurations: The Foundation of Interior Space

The Sierra 1500 offers three distinct cab configurations, each providing different interior dimensions to suit various needs:

Regular Cab Interior Dimensions

The Regular Cab represents the most straightforward configuration, available exclusively in the Pro trim level. This work-focused option provides:

• Front Headroom: 1,092 mm (43.0″)
• Front Legroom: 1,131 mm (44.5″)
• Passenger Capacity: Up to 3 occupants
• Seating Configuration: Single row bench seat or optional bucket seats

The Regular Cab prioritizes front-row spaciousness while maintaining a more compact exterior footprint. With no rear seat, this configuration maximizes bed length options for those who value cargo capacity over passenger space. Despite its utilitarian focus, the Regular Cab still provides generous front dimensions that accommodate drivers of various sizes.

Double Cab Interior Dimensions

Moving up to the Double Cab configuration, available in Pro, SLE, and Elevation trims, introduces a second row of seating with rear-hinged doors for easier access. Key dimensions include:

• Front Headroom: 1,092 mm (43.0″)
• Front Legroom: 1,131 mm (44.5″)
• Rear Headroom: 1,020 mm (40.1″)
• Rear Legroom: 886 mm (34.8″)
• Passenger Capacity: Up to 6 occupants
• Seating Configuration: Front and rear bench seats or front bucket seats with rear bench

The Double Cab configuration strikes a balance between passenger space and exterior dimensions, offering enough rear seat room for occasional passengers or regular trips with smaller adults or children. The front dimensions remain identical to the Regular Cab, ensuring driver and front passenger comfort isn’t compromised.

Crew Cab Interior Dimensions

The Crew Cab represents the most spacious and versatile configuration, available across all trim levels from Pro to Denali Ultimate. This family-friendly option features:

• Front Headroom: 1,092 mm (43.0″)
• Front Legroom: 1,131 mm (44.5″)
• Rear Headroom: 1,019 mm (40.1″)
• Rear Legroom: 1,102 mm (43.4″)
• Passenger Capacity: Up to 6 occupants
• Seating Configuration: Front and rear bench seats or front bucket seats with rear bench

The Crew Cab’s significantly expanded rear legroom provides a comfortable experience for adult passengers on longer journeys. With nearly identical legroom in both rows, the Crew Cab delivers sedan-like comfort in a pickup truck package. This configuration is ideal for families or those who regularly transport multiple passengers.

Interior Dimensions Across Trim Levels

While the basic dimensions remain consistent across cab configurations, the interior experience varies significantly by trim level due to seating materials, adjustability options, and overall design. Let’s explore how each trim enhances the Sierra interior space:

Pro Trim Interior

The Pro trim serves as the foundation of the Sierra 1500 lineup and is available in all three cab configurations. Its interior features:

• Seating Material: Vinyl or cloth seats
• Front Seat Adjustability: Manual adjustments
• Center Console: Minimal design focused on functionality
• Storage Solutions: Basic door pockets and under-seat storage

Despite its work truck positioning, the Pro trim maintains the same generous headroom and legroom dimensions as higher trims, ensuring comfort for daily operations. Its straightforward interior design maximizes usable space without unnecessary frills.

SLE and Elevation Trim Interiors

The SLE and Elevation trims elevate the interior experience while maintaining the same fundamental dimensions:

• Seating Material: Premium cloth with optional leather appointments
• Front Seat Adjustability: Available 10-way power driver seat
• Center Console: Enhanced design with additional storage compartments
• Storage Solutions: Expanded door pockets and configurable center console

These mid-level trims enhance the spacious Sierra interior with improved materials and greater adjustability, allowing drivers to customize their comfort. The Elevation trim adds distinctive design elements while maintaining the same interior dimensions as the SLE.

SLT Trim Interior

The SLT trim significantly enhances comfort within the same dimensional framework:

• Seating Material: Perforated leather appointments
• Front Seat Adjustability: 10-way power-adjustable front heated and ventilated bucket seats
• Center Console: Premium design with enhanced functionality
• Storage Solutions: Up-level rear storage package with full-length bench seat offering additional storage options

The SLT transforms the interior space through premium materials and advanced comfort features. The available heated and ventilated seats make the most of the generous dimensions by enhancing comfort in various weather conditions.

AT4 and AT4X Trim Interiors

The off-road focused AT4 and premium AT4X trims maintain the same basic dimensions while adding distinctive touches:

• Seating Material: Unique leather appointments with contrast stitching
• Front Seat Adjustability: 10-way power adjustments with position memory
• Center Console: Ruggedized design with additional off-road controls
• Storage Solutions: Advanced storage systems, including secure compartments for adventure gear

These adventure-oriented trims maximize interior comfort for off-road excursions, featuring specialized seating that provides support in demanding driving conditions while maintaining the Crew Cab’s spacious dimensions.

Denali and Denali Ultimate Trim Interiors

At the pinnacle of the Sierra 1500 lineup, the Denali and Denali Ultimate trims represent the ultimate expression of interior comfort:

• Seating Material: Premium leather with exclusive perforation patterns
• Front Seat Adjustability: 12-way power adjustments with position memory, massage function
• Center Console: Premium design with open-pore wood trim and metal accents
• Storage Solutions: Comprehensive storage options with premium materials and finishing

The Denali trims enhance the interior dimensions with exceptional materials and craftsmanship, delivering a truly premium experience. While the measurements remain consistent with other Crew Cab models, the execution creates a distinctly different sense of spaciousness and luxury.

Interior Space Utilization Features

Beyond raw dimensions, the Sierra 1500 offers several features that maximize the utility of its interior space:

Flexible Seating Arrangements

Depending on the trim level, the Sierra 1500 offers:

• Front Center Seat Conversion: On models with front bench seats, the center position converts to a work surface when not in use
• Rear Seat Flexibility: Crew Cab models feature rear seats that fold up to create additional interior cargo space
• Under-Seat Storage: Hidden compartments beneath the rear seats maximize interior storage options

These versatile features allow owners to adapt the interior space to their changing needs, effectively increasing the utility of the dimensional specifications.

Premium Technology Integration

Advanced technology enhances the feeling of spaciousness through thoughtful integration:

• 13.4-inch Diagonal Touchscreen: Available on SLE trims and above, the large display provides information and controls without encroaching on interior space
• 12.3-inch Digital Driver Information Center: Customizable display replaces traditional gauges on most trims, creating a more open dashboard design
• Head-Up Display: Available on premium trims, this technology provides information without requiring drivers to look away from the road

By relocating controls and information to digital interfaces, these technologies create a cleaner, more open interior environment while maintaining all necessary functionality.

Compare Sierra 1500 Interior Space Across Generations

The Sierra 1500 builds upon the GMC legacy of interior spaciousness with several improvements over previous generations:

• Front Legroom Enhancement: The current generation provides 25 mm (1″) more front legroom than earlier models
• Rear Headroom Optimization: Revised roof design maintains generous headroom despite sleeker exterior styling
• Interior Width Utilization: Thoughtful door panel design maximizes shoulder and hip room within the cabin

These enhancements demonstrate the GMC commitment to continually refining the Sierra interior dimensions for improved comfort and functionality.

2026 GMC Sierra: Comfort and Capability 

The GMC Sierra 1500 delivers thoughtfully designed interior dimensions across its range of cab configurations and trim levels. From the work-ready Regular Cab Pro to the luxurious Crew Cab Denali Ultimate, each model provides spacious accommodations that prioritize passenger comfort without compromising capability. Whether you’re seeking a practical work truck or a premium family vehicle, the Sierra 1500 interior dimensions create a foundation for both functionality and refinement.

Questions and Answers About the 2026 Sierra 1500 Interior Dimensions

Which 2026 Sierra 1500 configuration offers the most rear legroom?

• The Crew Cab configuration provides the most generous rear legroom at 1,102 mm (43.4″), nearly matching the front legroom dimension. This makes it ideal for families or those who regularly transport adult passengers in both rows.

Does the front headroom vary between Sierra 1500 trim levels?

• No, the front headroom measurement of 1,092 mm (43.0″) remains consistent across all trim levels within the same cab configuration. The only differences between trims are the seating material, adjustability options, and overall refinement.

How does the Regular Cab maximize its interior space without rear seats?

• The Regular Cab focuses exclusively on front-row comfort with the same generous headroom and legroom as other configurations. Without rear seats, it offers additional behind-seat storage space for items that need to be secured inside the cab rather than in the bed.

Are there dimensional differences between the 2025 and 2026 Sierra 1500 interiors?

• The core interior dimensions remain unchanged between the model years. The new model continues with the same spacious cabin architecture while offering updated technology and trim-specific enhancements.

How do the Sierra 1500 interior dimensions compare to its major competitors?

• It offers class-competitive interior dimensions, with the Crew Cab configuration providing among the most generous rear legroom in the full-size pickup segment. This passenger-friendly approach distinguishes this truck from competitors that prioritize bed space over rear-seat room.

Disclaimer: Content contained in this post is for informational purposes only and may include features and options from US or international models. Please contact the dealership for more information or to confirm vehicle, feature availability.