Cargo Van Bed: Bed Height & Garage Math for Sprinter and Transit Builds

How to choose the right cargo van bed height so your gear fits and you still sleep comfortably

By The Vansmith · November 2025

Picking the right bed height is where layout design meets real-world use. Get the math and trade-offs right and you can store two mountain bikes and a pair of skis, sleep on a comfortable foam mattress, and still stand or sit up without banging your head. Get it wrong and you lose usable storage or end up sleeping in a cramped coffin. This guide walks through the formulas, practical rules-of-thumb, and platform options we use on Sprinter and Transit builds so you can make a confident choice for your van.

Download our free Clearance Calculator (link below) to run numbers for your exact van and gear.

Key takeaways: set your platform between 20–26 inches for most multi-sport vanlifers; use 3–4" foam for balanced comfort and headroom in most Sprinters; prefer aluminum-extrusion framing if you need higher load capacity without adding bulk.

What “garage math” means for your conversion

Garage math is the clearance arithmetic that determines whether your biggest gear—bikes, skis, snowboards, or even a small dirt bike—will fit under your bed while still leaving comfortable mattress and headroom above. It’s a short chain of measurements and subtractions:

• Interior ceiling height (measured at the lowest point)
• Minus desired head clearance above mattress (sit-up or comfy headroom)
• Minus mattress thickness and bedding stack
• Equals maximum platform height (which in turn determines under-bed garage height after framing thickness)

Example: an 80" Sprinter interior — subtract 36" of headroom (comfortable sitting), subtract a 4" mattress and a 2" mattress deck/finish = 38" for platform top elevation, meaning platform sits at ~42" above the floor. That math is flexible—most Vansmith layouts target lower platform heights (20–26") because they prioritize a usable garage rather than full sit-up headroom in the bed area.

Step-by-step clearance formula you can use right now

Use this simple formula on paper or in our Clearance Calculator:

Platform height above floor = Interior ceiling lowest point - Desired headspace above mattress - Mattress thickness - Decking & framing thickness

Notes:

• Desired headspace: 30–36" for being able to sit up comfortably; 24–30" if you mostly lie down and don’t need to sit upright in bed.
• Mattress thickness: 3–6" depending on foam density. Thicker mattresses improve sleep but cut headroom.
• Decking & framing thickness: 1.5–4" depending on plywood thickness and framing style (slotted aluminum extrusion decks can be thinner and lighter).

Place a conservative safety margin (0.5–1") for bedding loft and pillow stacks.

Download the Vansmith Clearance Calculator

Common target platform heights and what they let you store

• 18–20 inches — Minimal garage for low-profile bikes, touring bikes on wheels, or soft duffels. Good when headroom is the priority; not enough for two full-suspension MTBs unless wheels are removed or bikes are angled.
• 20–24 inches — Sweet spot for most vanlifers who want to store two mountain bikes, a pair of skis, or larger duffels. Works well with 3–4" mattresses and still leaves decent sit-up height in Sprinters.
• 24–30 inches — Larger garage for motorcycles, full-size bikes with wheels, or stackable gear systems. Be mindful this reduces mattress/headroom trade-offs—plan a thinner mattress or a lofted seating area.

Platform framing and materials: why it matters

The frame type affects your decking thickness, usable under-bed height, and load capacity:

• Simple plywood framing: inexpensive and serviceable. Expect 1.5–2" decking thickness plus joists—good for light loads and DIY.
• Aluminum extrusion rails (our go-to for Sprinters): lower profile, lighter, and much higher load capacity per pound—allows a thinner deck and more under-bed clearance.
• C-channel steel frames: very strong for heavy motorcycle use but heavier overall; consider only if you need very high payload and don’t mind extra weight.

At The Vansmith, we often specify CNC-cut aluminum extrusion paired with marine plywood decking for a balance of light weight, rigidity, and a low finished profile—this lets us nudge an extra inch or two of usable garage space without sacrificing load rating.

Mattress choices and ceiling-height trade-offs

Mattress thickness is the single most common thing people underestimate. Our field survey showed most DIYers undercount the mattress stack when planning headroom. Practical recommendations:

• 3" high-density foam: minimal thickness, still supportive for short trips and slimmer sleepers.
• 3–4" high-density or layered foam: the best balance—sleep quality and headroom preservation. Vansmith standard for most layouts.
• 5–6" luxury foam: for full-time vanlifers who prioritize sleep over headroom; pair with taller interiors (longer-wheelbase Sprinters or Transit high-roof where possible).

Pro tip: choose foam density carefully—higher density gives better support at lower thickness. Our guides on mattress selection explain the density vs thickness trade-offs in detail (Camper Van Bed Plans and Ideas).

Real-world case studies: Sprinter and Transit examples

Case 1 — Sprinter 170" high-roof, dual-sport couple: We set platform at 22" to fit two mountain bikes side-by-side on a slide-out deck, use 3.5" foam mattress, and retain ~34" sit-up headroom. Result: easy bike access, comfortable sleep, and long-term usability.

Case 2 — Transit High-Roof, solo motorcycle owner: Platform set at 28" with reinforced C-channel frame and integrated ramp. Mattress is a 3" high-density foam topper for minimal thickness. Result: motorcycle fits under deck, but interior headroom above bed is tighter—fine for solo users who don't need to sit up in bed.

We document more examples in our Transit conversion gallery showing measurement diagrams and build notes: Transit conversion gallery.

Design decisions: drawers vs slide-out deck vs permanent platform

Choice depends on how you use your garage:

• Frequent access to small items: deep drawers are convenient and organized.
• Large gear (bikes, skis, boards): slide-out decks or full-width drawers make loading quick and reduce crawling under the bed.
• Motorcycle or ATV: fixed platform with an integrated ramp and heavy-duty tie-downs is safest.

At The Vansmith we often combine solutions — a slide-out deck for bikes and large gear plus shallow drawers at the side for tools and kitchen items, giving the best of both worlds. See our service and custom bed pages for installation options: Foundation builds and Custom build process.

Load ratings: how much weight should your bed hold?

Think about static load (mattress + people) and dynamic load (loading/unloading gear). Reasonable targets:

• DIY plywood builds: 400–600 lbs if well-anchored and framed.
• Aluminum extrusion frames: 600–1,000+ lbs depending on anchoring and spanning supports.
• Reinforced steel C-channel: 1,000+ lbs for heavy motorcycle use.

We recommend designing with a margin—spec your frame for at least 25–30% more capacity than your expected maximum load. The Vansmith bed systems for Sprinters are typically engineered to the 800–1,000 lb range when properly anchored to OEM floor tracks.

Practical layout checklist before finalizing platform height

1. Measure your van interior at the lowest point (often above the wheel wells or under roof ribs).
2. Measure your tallest gear in the stowed position (bike standing on wheel, skis in bag, motorcycle w/ handlebars).
3. Decide how much sit-up headroom you want above the mattress (30–36" typical for sit-up; 24–30" if not).
4. Pick mattress thickness based on density and sleep preferences (3–4" typical).
5. Estimate decking/framing thickness based on chosen system (1.5–3"), then insert into the clearance formula.
6. Confirm load capacity and anchoring details with your builder or before committing to a DIY design.

Need a printable checklist? Grab the Vansmith pre-build checklist at our blog index: All Blogs.

When to call a pro (and when DIY is fine)

DIY is great for simple plywood platforms and light storage needs. Call The Vansmith if you need:

• High load capacity for motorcycles or heavy cargo
• Precision-fit modular slide-outs or integrated ramps
• Low-profile aluminum-extrusion frames requiring CNC work and exact anchoring
• Full-service design validation for Sprinter or Transit platform integration

We provide custom bed frame design and installation and can validate your clearance math on a quick consult: Contact us.

Quick rules of thumb

• Start assuming 3–4" mattress unless you sleep poorly—then add thickness and subtract headroom.
• Set a practical platform target of 20–24" for most bike/ski/multi-sport users.
• Use aluminum extrusion to gain under-bed inches without adding weight.
• Choose slide-outs for heavy/awkward gear and drawers for frequent small-item access.

Frequently Asked Questions