# Booster car seats that fit three across in a back seat Which booster car seats are reported to fit three across in a vehicle's back seat? Diono Connect3 RXT: Diono says it fits three\-across and is less than 17 inches wide without sacrificing interior seat space\. A parent reports that a Diono backless booster fits in the middle between two Diono Radian 3R seats in a Subaru Forester with no fit issues, and that a similar setup also fit in a small Tesla and a RAV4\. Peg Perego Viaggio Flex 120: Its narrow footprint made a difficult three\-across situation work, and despite having no armrests the belt fit was consistently good across the vehicles and seating positions tried\. Britax UpNGo Click: The seat is 17\.1 inches wide and is designed to fit three across in most vehicles, but Britax will not guarantee 3\-across fitment in every vehicle\. Britax UpNGo: The maker does not guarantee that three of these seats will fit across every vehicle's back seat\. The seat is 17\.1 inches wide \(SpaceSaver design\), intended to leave room for siblings or carpoolers\. ### 1. [Diono Connect3 RXT](/products/ucp/megababiesusa-com/8673372274942) (sold by megababiesusa\.com) Diono says it fits three\-across and is less than 17 inches wide without sacrificing interior seat space\. - Three\-across fit: Diono says it fits three\-across and is less than 17 inches wide without sacrificing interior seat space\. (listing) - Width: The seat measures 9\.1 inches high, 16\.3 inches wide and 15\.4 inches deep\. (listing) ### 2. [PEG Perego Viaggio Flex 120](/products/ucp/albeebaby-com/9564437938407) (sold by albeebaby\.com) Its narrow footprint made a difficult three\-across situation work, and despite having no armrests the belt fit was consistently good across the vehicles and seating positions tried\. - Three\-across fit: Its narrow footprint made a difficult three\-across situation work, and despite having no armrests the belt fit was consistently good across the vehicles and seating positions tried\. (blog) - Width: - ### 3. [Britax UpNGo Click](/products/ucp/strolleria-com/8008999993418) (sold by strolleria\.com) The seat is 17\.1 inches wide and is designed to fit three across in most vehicles, but Britax will not guarantee 3\-across fitment in every vehicle\. - Three\-across fit: The seat is 17\.1 inches wide and is designed to fit three across in most vehicles, but Britax will not guarantee 3\-across fitment in every vehicle\. (listing) - Width: The seat is 17\.1 inches wide and is designed to fit three across in most vehicles, but Britax will not guarantee 3\-across fitment in every vehicle\. (listing) ### 4. [Britax UpNGo](/products/ucp/strolleria-com/8085815623754) (sold by strolleria\.com) The seat is 17\.1 inches wide \(SpaceSaver design\), intended to leave room for siblings or carpoolers\. - Three\-across fit: The maker does not guarantee that three of these seats will fit across every vehicle's back seat\. (listing) - Width: Assembled dimensions are 15\.5 inches long, 17\.1 inches wide and 9 inches high\. (guide) ## Also cited in the text - Diono Connect3 RXT, three\-across fit: A parent reports that a Diono backless booster fits in the middle between two Diono Radian 3R seats in a Subaru Forester with no fit issues, and that a similar setup also fit in a small Tesla and a RAV4\. (review) - Britax UpNGo, seat width and three\-across fit: The seat is 17\.1 inches wide \(SpaceSaver design\), intended to leave room for siblings or carpoolers\. (guide) Every value in the table is a fact RoboTrunk checked, linked to the page it came from\. A dash means no checked fact fills that cell\. Prices and stock change, so this page prints neither: each product name links to its RoboTrunk page, which shows them live\. Written 2026-10-19T06:27:10.347Z. This page is published by RoboTrunk, a store built for shopping agents. The store named on this page sells the product and ships it. RoboTrunk is not the seller and never holds the money. Buying works in one path. RoboTrunk's tools prepare a checkout at that store, then hand back a short-lived link. 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