2018-2023 Subaru Crosstrek (XV) 2nd Gen — subwoofer box fitment

What we researched for this specific generation: where an enclosure actually fits, what the factory speakers are, how the factory audio is wired, and which real builds and commercial products exist for it. Confidence badges say how well each figure is sourced — this is research, not manufacturer spec.

Body styles covered: 4-Door Crossover

Where a box actually fits

These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.

Standard Likely

Locationunder front passenger seat (zero cargo loss) or behind rear seat (factory powered option)
Outer bounding boxCargo width between wheel housings ~43"; liftgate opening ~42"W x 29"H; not independently measured for a specific box footprint
Known obstructionsTrapezoid-shaped boxes recommended for custom builds to minimize sound wave cancellation
Usable volume estimate0.5 ft³

Starting points

Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.

Budget

Subwoofersunder-seat passive (e.g. MSP 25-style)
Box typesealed
Locationunder front passenger seat, zero cargo loss

Enthusiast

SubwoofersOEM Kicker 10" powered unit, or custom trapezoid box
Box typesealed
Locationbehind rear seat

Door speaker fitment

Sizes and depths below are what research turned up for this generation. Confirm against your own vehicle before cutting or ordering — trim levels vary.

Front doors Likely

Factory speaker size6-3/4"
Known obstructionsNone specifically documented
Adapter bracket neededunconfirmed
TweeterDash-corner-mounted — real, confirmed (sources vary slightly, 3"-3.5", one owner fit a 4" aftermarket unit as a tight replacement). Plays from ~6kHz up with a small cap on the factory unit.

Rear doors Likely

Factory speaker size5-1/4"
Known obstructionsNone specifically documented
Adapter bracket neededunconfirmed
Tweetern/a — tweeter is dash-corner mounted, front only

Factory audio integration

Factory amp / premium audioReal, specific hardware spec confirmed. Harman Kardon premium audio on the Limited trim: 8 speakers, 432W. Boundary note for accuracy: a real 2024 Crosstrek finding (HK system gains a subwoofer) exists but falls OUTSIDE this entry's 2018-2023 span — do not backdate that subwoofer addition into this generation without separate confirmation.
Adding subs without a head-unit swapConfirmed straightforward — the OEM Kicker accessory and under-seat options both avoid the head unit
Head unitNo replacement needed

Known integration products

Mounting locations

Standard Likely

Real measured cargo: 19.9 ft3 behind rear seats, 54.7 ft3 seats folded, liftgate opening ~42"W x 29"H, folded load floor ~64"L, cargo width between wheel housings ~43". REAL FACTORY OPTION: Subaru sells a genuine OEM Kicker-branded powered subwoofer (H630SFJ101) that's a self-contained unit mounting behind the rear seat — a real manufacturer accessory, not just third-party. For cargo-preserving builds, an under-seat passive subwoofer (e.g. MSP 25 under the front passenger seat) is a real documented zero-cargo-loss option. Design tip found: a trapezoid-shaped box is recommended for custom builds to minimize sound wave cancellation.

Builds and products found for this vehicle

Outside links. Some are commercial products, some are owner builds posted on forums — the label says which. We do not endorse any of them.

Build it for this vehicle

Each link opens the tool with this vehicle already selected.

Before you cut anything

Measure your own vehicle. Trim levels, factory subwoofer options, and mid-generation changes all move these numbers, and a box cut to a researched figure that does not match your truck is wasted wood. Where a badge reads Unconfirmed, treat the value as a starting point for your own measurement, not as an answer.