# Booster seats that fit three across in one back seat Which booster seats fit three across in a single back seat? Diono Connect3 RXT Backless Booster with Latch: 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 / Peg Perego Primo Viaggio Flex 120: It is a go\-to narrow booster for tight three\-across setups because it is 14 inches at the seat bottom and 17 inches at its widest in narrow mode\. The booster is narrow and lacks armrests, so it fit the reviewer's tricky three\-across situation\. 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 seat is 17\.1 inches wide \(SpaceSaver design\), intended to leave room for siblings or carpoolers\. The maker does not guarantee that three of these seats will fit across every vehicle's back seat\. Britax Highpoint 2\-Stage Belt\-Positioning Booster Car Seat: The retailer claims the seat fits three across, though no compatible vehicle list or installation measurements are supplied\. Consumer Reports lists a 17\-inch base, 21\-inch overall width and 35\-inch overall height, with no width adjustment\. ### 1. [Diono Connect3 RXT Backless Booster with Latch](/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\. - Width: The seat measures 9\.1 inches high, 16\.3 inches wide and 15\.4 inches deep\. (listing) - 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) - Weight: The seat weighs 9\.1 pounds\. (listing) ### 2. [PEG / Peg Perego Primo Viaggio Flex 120](/products/ucp/strolleria-com/3782284247114) (sold by strolleria\.com) It is a go\-to narrow booster for tight three\-across setups because it is 14 inches at the seat bottom and 17 inches at its widest in narrow mode\. - Width: It is a go\-to narrow booster for tight three\-across setups because it is 14 inches at the seat bottom and 17 inches at its widest in narrow mode\. (blog) - Three\-across fit: The booster is narrow and lacks armrests, so it fit the reviewer's tricky three\-across situation\. (blog) - Weight: The store page lists the car seat weight as 14\.8 lbs, while an independent test measured about 15\.7 lbs; the sources disagree on the weight\. (guide) ### 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\. - Width: The maker lists rigid LATCH click\-in, a 17\.1\-inch slim SpaceSaver design, the PosturePlus contoured seat, a carry weight under 5 lb, two dishwasher\-safe cup holders, a washer\-and\-dryer\-friendly cover, naturally flame\-retardant fabrics with no added FR chemicals, colour\-coded belt guides and a shoulder belt guide\. (guide) - 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) - Weight: The maker lists rigid LATCH click\-in, a 17\.1\-inch slim SpaceSaver design, the PosturePlus contoured seat, a carry weight under 5 lb, two dishwasher\-safe cup holders, a washer\-and\-dryer\-friendly cover, naturally flame\-retardant fabrics with no added FR chemicals, colour\-coded belt guides and a shoulder belt guide\. (guide) ### 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\. - Width: Assembled dimensions are 15\.5 inches long, 17\.1 inches wide and 9 inches high\. (guide) - Three\-across fit: The maker does not guarantee that three of these seats will fit across every vehicle's back seat\. (listing) - Weight: Sources disagree on seat weight: the store listings give 3\.1 lb, while Consumer Reports gives 5 lb\. (listing) ### 5. [Britax Highpoint 2\-Stage Belt\-Positioning Booster Car Seat](/products/ucp/anbbaby-com/6577953243222) (sold by anbbaby\.com) The retailer claims the seat fits three across, though no compatible vehicle list or installation measurements are supplied\. - Width: Consumer Reports lists a 17\-inch base, 21\-inch overall width and 35\-inch overall height, with no width adjustment\. (review) - Three\-across fit: The retailer claims the seat fits three across, though no compatible vehicle list or installation measurements are supplied\. (guide) - Weight: Consumer Reports lists the seat at 12 lb in high\-back form and 6 lb in backless form\. (review) ## Also cited in the text - Diono Connect3 RXT Backless Booster with Latch, 3\-across width: Diono says it fits three\-across and is less than 17 inches wide without sacrificing interior seat space\. (listing) - 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 2026-10-24T00:02:09.639Z. 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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