MightyFit 65 › fit in › Toyota Sienna

Will the Cosco MightyFit 65 fit in a 2011–2020 Toyota Sienna?

Yes — the Cosco MightyFit 65 fits a 2011–2020 Toyota Sienna.
The MightyFit 65 is about 18" wide; the Sienna's usable rear bench is about 54". It fits one rear position comfortably. Three across is tight (54" needed vs 54").

18"MightyFit 65 width

54"Sienna rear bench

Tightthree across

★★★☆☆NHTSA Ease-of-Use

Check the MightyFit 65 on Amazon → All seats for a Sienna

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What fits this Sienna

One seat, rear position: Yes. The MightyFit 65 installs in an outboard rear position of a 2011–2020 Toyota Sienna with room to spare.
Three across: Tight — three need ~54" against only ~54". A narrower seat is the better bet.
Modes this seat covers: rear-facing → forward-facing.
LATCH: lower anchors up to 55 lb; the Sienna has 3 lower-anchor positions.

ℹ️ Informational only — built from NHTSA public car-seat ratings and published seat/vehicle dimensions. This is not a safety certification and not a substitute for the seat and vehicle manuals. Always confirm the fit and install yourself before every trip. The MightyFit 65's width (Cosco published spec (~18 in)) and the Sienna's rear-bench width (Toyota dimensions + owner measurements (approx)) are both approximate — confirm with a test-fit before buying.

Common questions

Will the Cosco MightyFit 65 fit in a 2011–2020 Toyota Sienna?

Yes — the Cosco MightyFit 65 (18" wide) fits a single rear seating position in a 2011–2020 Toyota Sienna. Three across is tight — its rear bench is about 54" and three of these would need 54".

Can you fit three MightyFit 65s across a Sienna?

Probably not — three MightyFit 65s need about 54" but the Sienna's usable bench is only about 54". Consider a narrower seat — see our narrowest-seats guide.

Sources: seat ratings & modes — NHTSA (pulled 2026-06-17); dimensions — manufacturer specs and owner measurements. Informational only — built from NHTSA public car-seat ratings and published seat/vehicle dimensions. This is not a safety certification and not a substitute for the seat and vehicle manuals. Always confirm the fit and install yourself before every trip.