Choosing the right semi truck bed size can make or break your sleep on the road. If you’re shopping for a new mattress or upgrading your sleeper cab, getting the dimensions wrong means wasted money and restless nights. The industry standard Size A mattress measures 36 inches wide by 80 inches long, fitting most popular long-haul trucks. This slightly narrower profile is purpose-built for compact sleeper berths.
This guide covers everything you need to know about semi truck bed dimensions, which trucks fit Size A mattresses, how to measure your berth accurately, and which mattresses deliver the best road-ready comfort. Whether you drive a Peterbilt, Freightliner, or International, you’ll learn how to pick a mattress that fits and lasts.
What Is a Size A Semi Truck Mattress?
A 36″ x 80″ mattress is the standard semi truck bed size for many over-the-road sleeper cabs. Known as Size A, this dimension is specifically engineered to maximize comfort in tight quarters. It matches the length of larger residential mattresses like queen and king but stays 2 inches narrower than a standard twin, leaving room for movement around the bunk.
Despite its compact width, Size A still offers full-body support. Most sleeper berths are built to precise factory specs, so using a non-standard mattress can cause shifting during transit, poor fit, or damage to surrounding panels.
Size A vs. Standard Mattress Dimensions
| Mattress Type | Width (in) | Length (in) |
|---|---|---|
| Size A Semi Truck | 36 | 80 |
| Standard Twin | 38 | 75 |
| Twin XL | 38 | 80 |
| Queen | 60 | 80 |
| King | 76 | 80 |
As the table shows, Size A matches the length of a twin XL, queen, and king, but its slimmer width makes it ideal for narrow sleeper compartments. Always confirm your berth’s internal dimensions before ordering.
Semi Trucks Designed for Size A Mattresses
Several popular semi-truck models come equipped with berths that accommodate a 36″ x 80″ Size A mattress.
Peterbilt 579 Sleeper
The Peterbilt 579 offers one of the most spacious sleeper cabs available, with multiple configuration options including extended roof caps. Its standard mattress size in many sleeper layouts is 36″ x 80″, making it fully compatible with Size A replacements.
Freightliner Cascadia
The Freightliner Cascadia is a top choice among professional drivers for its fuel efficiency and driver-focused design. Most Cascadia sleeper models come pre-equipped with a 36″ x 80″ mattress, and the cabin layout is optimized for this dimension. Always verify your specific model’s berth before ordering, especially if customized.
International 56″ Sleeper
The International 56″ Sleeper is built for long-haul efficiency with a no-frills, durable design. It typically uses the standard Size A mattress, making replacements easy to source. Because of its compact footprint, precise measurements are critical here. Any oversized mattress will not fit without modification.
Pro Tip: Even within the same model line, sleeper configurations can vary. Always measure your berth before purchasing a new mattress.
How to Measure Your Sleeper Berth
Don’t rely solely on manufacturer specs. Measure your sleeping area yourself to ensure a perfect fit.
Step-by-Step Measurement Process
- Remove the old mattress to access all sides of the berth frame.
- Measure width from left to right inside the berth frame, not the cab wall. Record the narrowest point.
- Measure length from the back wall to the front edge of the frame, including any lip or cover.
- Check for obstructions like seat backs, latches, or side rails that could interfere with placement.
- Compare to Size A (36″ x 80″). If your measurements fall between 35.5″–36.5″ wide and 79.5″–80.5″ long, a Size A will likely fit.
Warning: Even a 1-inch discrepancy can prevent proper installation. When in doubt, choose slightly smaller rather than larger.
Best Size A Mattress Options for Truckers
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After confirming your semi truck bed size, choose a mattress built for durability, support, and road vibrations. Two top-rated options stand out.
SleepDog® Mattress: 7″ Medium-Firm Support
The SleepDog® Size A mattress features 7 inches of multilayer memory foam infused with CoolRest® technology to regulate temperature on long drives. Its medium-firm feel suits most sleeping styles.
Key benefits include:
- Motion isolation to minimize disturbance from cab movement
- CertiPUR-US® certified foam, free of harmful chemicals
- DOT approval for safe transportation use
- 120-night sleep trial included
This mattress works well for drivers wanting a low-profile, supportive option without excess bulk.
BigDawg Mattress®: 9″ Plush Pillow-Top Comfort
For drivers prioritizing luxury, the BigDawg Mattress® delivers with a 9-inch plush build and pillow-top design. It is the brand’s best-seller.
Notable features:
- Double-sided design you can flip for soft or firm feel
- Quilted foam cover for added cushion and breathability
- Excellent pressure relief for joint pain or long shifts
The BigDawg® is currently on sale for 35% off during the Labor Day promotion, starting at $454.35 (originally $699).
Why Road-Ready Construction Matters
A semi truck bed is more than a place to nap. It’s your home on the highway. Your mattress must handle constant motion, temperature swings, and years of heavy use.
CertiPUR-US® and DOT Approval
Both SleepDog® and BigDawg® mattresses use CertiPUR-US® certified foam, meaning every layer has been independently tested. Certification confirms the foam is:
- Free from PBDEs, CFCs, and formaldehyde
- Low in VOC emissions for healthier air quality
- Safe for enclosed sleeping environments
DOT approval confirms the foam can withstand vibration, acceleration, and deceleration forces common in commercial trucking.
Motion Transfer Reduction
Trucks shift, stop, and turn constantly. Quality memory foam absorbs these vibrations, reducing fatigue and helping you stay asleep through rough roads.
120-Night Risk-Free Sleep Trial
Not sure which firmness level suits you? SleepDog® offers a 120-night risk-free trial on all Size A mattresses.
The process works like this:
- Sleep on the mattress for at least 60 nights so your body adjusts.
- If unsatisfied, contact support to start the return process.
- Receive free pickup and a full refund with no restocking fees.
This trial lets you test the mattress across different routes, weather conditions, and driving scenarios.
Note: Returns require 60+ nights of use. See the full Return Policy for details.
Flexible Financing Through Affirm
Upgrading your semi truck bed setup shouldn’t strain your budget. SleepDog® partners with Affirm to offer flexible financing options.
Qualifying customers enjoy:
- Fixed monthly payments
- Interest rates from 0% to 30% APR
- No credit score impact during pre-qualification
Select Affirm at checkout, complete a quick application, and choose a payment plan spanning 6, 12, or 24 months.
Common Mistakes to Avoid When Buying a Truck Mattress
Even experienced drivers make errors when replacing their mattress. Watch out for these pitfalls.
- Assuming all twin beds are the same. A standard twin is 38″ wide, but Size A is only 36″. A residential twin will likely be too wide.
- Skipping the measurement step. Truck configurations vary. Always measure every time.
- Choosing non-DOT approved foam. Foam not rated for transportation may break down faster or off-gas excessively in enclosed spaces.
- Ignoring firmness preferences. Side sleepers often prefer medium-soft surfaces, while back or stomach sleepers may need firmer support. The double-sided BigDawg® lets you test both.
Maintenance Tips for a Longer-Lasting Mattress
Extend the life of your Size A mattress with these simple habits:
- Use a protective cover to guard against spills and wear
- Air out the berth weekly to reduce moisture buildup
- Rotate the mattress every 3 months if it’s double-sided
- Avoid folding or compressing during storage
A well-maintained memory foam mattress can last 5–7 years on the road.
Frequently Asked Questions About Semi Truck Bed Sizes
What are the exact dimensions of a Size A semi-truck mattress?
Size A semi-truck mattresses measure 36 inches wide by 80 inches long. They are 2 inches narrower than a standard twin but share the same 80-inch length as twin XL, queen, and king mattresses.
Which semi-truck models fit a Size A mattress?
Peterbilt 579, Freightliner Cascadia, and International 56″ Sleeper models are commonly equipped with Size A mattresses. Always measure your specific berth before purchasing.
What makes a truck mattress suitable for over-the-road use?
Look for DOT approval and CertiPUR-US® certified memory foam. These certifications confirm the foam has been tested for safety, low emissions, and durability under road vibration.
Is there a trial period for Size A truck mattresses?
Yes. SleepDog® offers a 120-night risk-free trial. You must sleep on the mattress for at least 60 nights before initiating a return.
What financing options are available for truck mattresses?
SleepDog® partners with Affirm to offer flexible financing with monthly payments and APR rates between 0% and 30%. Pre-qualifying won’t affect your credit score.
Key Takeaways for Choosing Your Semi Truck Bed Size
The semi truck bed size you need is most likely 36″ x 80″ (Size A), especially if you drive a Peterbilt 579, Freightliner Cascadia, or International 56″ Sleeper. Don’t guess on dimensions. Measure your berth accurately and choose a DOT-approved, CertiPUR-US® certified mattress for maximum comfort and durability.
With a 120-night trial and financing through Affirm, upgrading your sleep setup is risk-free and budget-friendly. Measure your berth today, pick a mattress that matches your driving style, and start getting the restful sleep you deserve mile after mile.
