KALLAX Shelf unit, white, 30 1/8x30 1/8 "
+10⅜″ margin
Will fit in a ?
No, it won't fit.
It will not fit in this setup: BILLY Bookcase, black oak effect, 31 1/2x11x79 1/2 " is too large for a Citroen C5 Aircross 2021 with seats up.
Fit Details
With seats up, This package will not fit in this setup. The blocker is opening width, and you're short by 23⅛″ even with diagonal loading. We're about 95% confident in this estimate.
BILLY Bookcase, black oak effect, 31 1/2x11x79 1/2 "
Box: 81¼″ × 11¾″ × 5″ · 86 lb 15 oz
Based on IKEA US (United States).
Package dimensions last checked and updated on Aug 06, 2026
Package
Status
Limiting factor
Best orientation
Package #1
81¼″ × 11¾″ × 5″
Status:23⅛″ short
Limited by
Limiting factor:Opening width
Best orientation:Diagonal
Vehicle limits
Opening width / height
41″ / 30¾″
Cargo width / height
41¾″ / 32¼″
Cargo length seats up / down
38¼″ / 67¾″
Loading sill height
29⅛″
Citroen C5 Aircross 2021
Measurements last checked and updated on Aug 26, 2026
Helpful tips
Use these loading tips to improve your chances of fitting BILLY Bookcase, black oak effect, 31 1/2x11x79 1/2 " in Citroen C5 Aircross 2021.
Optimize opening width
Keep the narrow edge leading while entering the opening.
Load diagonally first
Load diagonally first, then straighten once inside.
Try fitting alternatives
Check the Similar items that fit section for safer alternatives.
Alternatives that fit in Citroen C5 Aircross 2021
Ranked by fit margin and package-dimension similarity. This improves as we index more items.
About the Citroen C5 Aircross 2021 boot
The C5 Aircross gives you a wide, square loading mouth: 41″ across and 30¾″ tall, with a floor that is actually wider than the opening at 41¾″ between the arches. Seats up you get 38¼″ of length; folding them stretches that to 67¾″, a gain of 29½″. The catch is the sill, which sits 29⅛″ off the ground, though the floor drops only 1⅝″ behind it, so boxes slide in level rather than falling in. Wide flat packs do well here; very long ones run out of floor before they run out of mouth. Lift heavy boxes to sill height first, rest them, then push.
About the BILLY Bookcase, black oak effect, 31 1/2x11x79 1/2 " package
The BILLY bookcase comes as a single long, flat box: 81¼″ × 11¾″ × 5″ and 86 lb 15 oz. It is the length that catches you out, not the weight on its own. That long panel wants a flat floor, which on most cars means folding the rear seats first. The board is rigid and will not flex around a wheel arch or a short boot, so it has to lie straight. An estate, a folded-seat hatchback, or an SUV takes it comfortably. Load it long-edge first, keep it flat, and guard the corners, because a knock at this weight cracks the edge.
Frequently asked questions
Find quick answers about fit for BILLY Bookcase, black oak effect, 31 1/2x11x79 1/2 " in Citroen C5 Aircross 2021, including seats up vs seats down, limiting factor, best orientation, and package-by-package margins.
Will BILLY Bookcase, black oak effect, 31 1/2x11x79 1/2 " fit in Citroen C5 Aircross 2021?
No. With seats up, it is short by 23⅛″ at Opening width, even with diagonal loading.
What is the tightest part?
The limiting factor is Opening width, with -23⅛″ margin in seats up.
What should I do instead?
Use the Helpful tips & alternatives section to choose a smaller item, different orientation, or split-load plan.
Is the trunk opening the issue?
Yes. The tightest constraint is at the opening (Opening width) with -23⅛″ margin.
How tight is this fit?
This result is in the clear no-fit band (-23⅛″ at Opening width).
Does it fit with seats up or seats down?
Seats up: No (-23⅛″). Seats down: No (-6⅜″). Default selection follows YES > MAYBE > NO.
Why does it not fit?
The blocker is Opening width. The worst margin is -23⅛″ in seats up, so clearance is below the required buffer.
Can I load it diagonally?
Yes, diagonal is the best orientation for this check, with -23⅛″ around the limiting point.
Which loading orientation works best?
Diagonal is the best orientation for this result in seats up.
How confident is this result?
Confidence is 95 out of 100 based on available dimensions and margin tightness.