Custom and RV Mattress Sizes: What to Measure Before Ordering

RVs, campers, antique bed frames, boat berths, and custom platforms often require mattresses in non-standard sizes. A standard Queen will not fit an RV platform, and a Twin will not fit an antique frame built decades ago. Ordering the wrong size means returns, delays, and frustration. This guide covers exactly what to measure before ordering a custom or RV mattress, so you get it right the first time.

What to Measure

Before you order a custom or RV mattress, you need four key measurements. Take each one carefully — even a half-inch difference can mean the mattress will not fit.

• Width. Measure the widest point of the platform or the current mattress. If the platform has raised edges or lip rails, measure the interior dimension — the space the mattress actually fits into.
• Length. Measure the longest point from top to bottom. In RVs, the length may be shorter than standard to accommodate a bathroom wall or slide-out mechanism.
• Depth (thickness). Measure from the platform surface to the top of the current mattress. If ordering a new depth, measure the available vertical clearance — especially in RVs with overhead cabinets or bunk beds.
• Corner shapes. Note whether the corners are square, rounded, angled, or cut out. See the next section for details.

For standard mattress dimensions as a reference point, see our size guide or our sizes page.

Corner Shapes and Cutouts

RV and boat mattresses frequently have non-standard corners. These are the most common shapes:

For rounded corners, measure the radius. For angled corners, measure the length of the angled edge and the two adjacent sides. For cutouts, measure the width and depth of the removed section. Sketch a diagram with all dimensions labeled and bring it to the showroom.

Mattress Depth and Clearance

Mattress depth matters more in RVs and custom platforms than in standard bedrooms. In an RV, overhead cabinets, bunk tops, or slide-out mechanisms may limit how thick the mattress can be. If the mattress is too thick:

• Cabinet doors may not close over the bed
• Bunk beds may not fold up properly
• The mattress may sit too high for comfortable access
• Sheets may not fit properly if the depth is unusual

Measure the vertical clearance from the platform to the lowest overhead obstruction. Subtract an inch for bedding, and that is your maximum mattress depth. Many RV mattresses are 6–8 inches thick for this reason.

Bedding Fit for Odd Sizes

Non-standard mattress sizes require non-standard bedding. Here is what to expect:

• Short Queen — requires RV-specific sheets. Standard Queen sheets will be 5–6 inches too long.
• Custom widths — may require custom-cut sheets or deep-pocket sheets that can be tucked.
• Unusual depths — check the pocket depth on fitted sheets. Standard pockets fit mattresses up to 14 inches; deeper mattresses need deep-pocket sheets.
• Mattress protectors — available in RV sizes from specialty bedding brands. A protector is still important for warranty and hygiene.

What to Ask Before Ordering

Before placing a custom or RV mattress order, confirm:

• ☐ All measurements have been double-checked
• ☐ Corner shapes are documented with a sketch
• ☐ Vertical clearance has been measured
• ☐ Production timeline is confirmed
• ☐ Whether the order is a special order (non-returnable)
• ☐ Bedding availability in the custom size
• ☐ Delivery options for your location

Custom and RV mattresses require careful planning, but getting the measurements right means you will have a mattress that fits perfectly. If you have measurements ready, contact us or visit a showroom near you to discuss your custom size needs with our Sleep Team.