KALLAX Shelf unit, white, 30 1/8x30 1/8″
+11¾″ margin
All items that fit a Citroen C5 Aircross 2021
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 21⅜″ 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 Oct 21, 2026
Package
Status
Limiting factor
Best orientation
Package #1
81¼″ × 11¾″ × 5″
Status:21⅜″ short
Limited by
Limiting factor:Opening width
Best orientation:Diagonal
Vehicle limits
Opening width / height above sill
41″ / 29⅛″
Cargo width / height
41¾″ / 30¾″
Cargo length seats up / down
38¼″ / 67¾″
Loading sill height
29⅛″
Citroen C5 Aircross 2021
Measurements last checked and updated on Oct 21, 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
From the loading sill to the floor, the C5 Aircross boot is almost level: the floor sits only 1⅝″ lower. The opening is 41″ wide with 29⅛″ of clear height above the sill, and the floor stays 41¾″ wide at its narrowest. Seats up, you get 38¼″ of floor, enough for several boxes or a box up to 29⅛″ tall standing up. Some flat packs longer than 38¼″ fit as well, angled across the floor on their side. Folding the rear seats adds 29½″, for 67¾″ in total. The sill itself is 29⅛″ off the ground. Lift each box onto the sill, then slide it forward.
About the BILLY Bookcase, black oak effect, 31 1/2x11x79 1/2″ package
You get the black oak effect BILLY in a single box, 81¼″ long, 11¾″ wide and 5″ thick. It weighs 86 lb 15 oz, and over that length the weight is hard to control, so plan on two of you, one at each end. Lying straight, it needs 81¼″ of boot floor, though its width and thickness still matter. Lift together on a count, so neither of you takes the full weight, even for a second. Set it down the same way, both ends at once.
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 21⅜″ at Opening width, even with diagonal loading.
What is the tightest part?
The limiting factor is Opening width, with -21⅜″ margin in seats up.
Why does it not fit?
The blocker is Opening width: with seats up, the box is 21⅜″ bigger than the space there.
Can I load it diagonally?
Yes, diagonal is the best orientation for this check, with -21⅜″ around the limiting point.
Which loading orientation works best?
Diagonal is the best orientation for this result in seats up.
Does it fit with seats up or seats down?
Seats up: No (-21⅜″). Seats down: No (-4¾″). Default selection follows YES > MAYBE > NO.
What do YES, MAYBE and NO mean here?
YES means there is at least 2⅜″ to spare at the tightest point, in the best way the box can go in. MAYBE means it fits on paper, but with less than 2⅜″ to spare, so trim, the parcel shelf or the loading angle can decide it. NO means the box is bigger than the space at its tightest point, whichever way it goes in. Every margin on this page is that real gap: the car's measurement minus the box's.
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 -21⅜″ margin.
How tight is this fit?
This result is in the clear no-fit band (-21⅜″ at Opening width).