BILBOX compatibility

How to measure your Subaru Forester SJ cargo area for a camper box

The BILBOX plans are designed for the 2013-2018 Subaru Forester SJ. In North America, the same SJ generation was sold as model years 2014-2018. Before you cut plywood, check your car's dimensions against the plans of the version you choose.

Three measurements for a first check

Empty the cargo area and leave the floor and trim panels set up the way they will be with the box in place. You'll need a tape measure. The figures below are guide values for Base and Plus.

  1. Width between the wheel arches: at least 1000 mm (39.4 in). Find the narrowest point between the inner wheel arch trims in the area the box will take up. Measure straight across the cargo area.
  2. Depth to the rear seat backs: at least 750 mm (29.5 in). Raise the rear seat backs to the upright driving position and measure lengthwise from the rear edge of the floor to the seat backs. Allow for the room that the trim of the closed tailgate takes up.
  3. Length to the front seat backs: at least 1850 mm (72.8 in). Fold the rear seat backs, set the front seats the way you will for sleeping, and measure from the rear edge of the cargo area to the front seat backs at the height of the future bed.
Plus diagram, rear view. Arrow 1 runs between the wheel arches: at least 1000 mm (39.4 in).
Diagram 1. Width between the wheel arches.
Plus diagram, side view. Arrow 2 marks the depth to the rear seat backs, at least 750 mm (29.5 in). Arrow 3 marks the length to the front seat backs with the rear seats folded, at least 1850 mm (72.8 in).
Diagrams 2 and 3. Cargo depth and length with the bed unfolded.

What else to check before cutting

  • Floor and supports. Check the slope of the floor and the height difference to the folded seat backs. Using the diagram for your version, check where the legs and extension panels will rest and whether the panels will lie flat in one plane.
  • Tie-down points. Find the factory tie-down hooks in the cargo area. Make sure you can still reach them with the box in place and that they are positioned so you can secure the box as the manual describes.
  • Opening and tailgate. Check that the box fits through the opening and that the tailgate closes with the box in place. With Plus, leave room to pull the drawers out with the tailgate open.
  • Spare wheel. In the author's Forester, it sits under the cargo floor. To get to it, first take out the removable parts, then the box.

Which Forester the fit was checked on

The Plus prototype was built and tested on trips in a 2017 Forester SJ. The Plus kit keeps the prototype's overall dimensions, with updated holes and fasteners. Base was designed in 3D, and its height was checked in the same car.

Folded BILBOX Plus prototype with two drawers in the cargo area of a Forester
The Plus prototype in a 2017 Forester SJ.

Even within the SJ generation, cargo areas can differ by trim and market, so measure your own car. For another generation or model, these three measurements are only a first guide: the floor shape, supports and tie-downs need a separate check. Send your make, model, year and measurements if you'd like to check the fit before you buy.

What to do after measuring

Compare Free, Base and Plus to choose the kit that suits your needs. See how the prototype was built from plywood to judge the amount of work before you order cutting.

The free PDF is available in English. Base and Plus come with Ukrainian text manuals for now; their picture manuals and DXF files have no words. If you'd like them in English, leave a request for an English edition.