# Car seats that fit three across in one back seat Which car seats fit three across in a single back seat? Diono Connect3 RXT Backless Booster: The slim design fits three across\. The seat is slim\-fit and measures less than 17 inches wide\. WAYB Pico: At under 15 inches wide it is one of the narrowest seats available, which is what makes three\-across possible\. Britax One4Life Slim: Shown fitting three across beside a Britax Poplar convertible and a Willow S infant seat; with the cup holders fitted it is wider than the bare 17\.5 in width\. Clek Fllo: The Fllo was described as the narrower, lighter alternative to the Foonf, at 25 lb, easier to move and install, and suited to three\-across in mid\-size sedans\. Although narrow, the seat is long rear\-facing and may require the front passenger seat to move far forward; it may not suit compact cars\. Maxi\-Cosi Kani 4\-in\-1 Convertible Car Seat: The three\-across fit is not guaranteed and depends on the vehicle model\. ### 1. [Diono Connect3 RXT Backless Booster](/products/ucp/goodbuygear-com/7641940131943) (sold by goodbuygear\.com) The slim design fits three across\. - Width: The seat is slim\-fit and measures less than 17 inches wide\. (listing) - Three\-across evidence: The slim design fits three across\. (listing) - Setup caveat: - - Limits: Suitable for children weighing 40\-120 lbs\. (listing) ### 2. [WAYB Pico](/products/ucp/modernnursery-com/4799011061860) (sold by modernnursery\.com) At under 15 inches wide it is one of the narrowest seats available, which is what makes three\-across possible\. - Width: In use the seat measures 15\.2 in long by 14\.5 in wide; it is 22\.8 in high with the headrest low and 27\.8 in at its highest, and folds to 11\.6 x 14\.5 x 18\.9 in\. (guide) - Three\-across evidence: At under 15 inches wide it is one of the narrowest seats available, which is what makes three\-across possible\. (review) - Setup caveat: - - Limits: - ### 3. [Britax One4Life Slim](/products/ucp/modernnursery-com/14905665585518) (sold by modernnursery\.com) Shown fitting three across beside a Britax Poplar convertible and a Willow S infant seat; with the cup holders fitted it is wider than the bare 17\.5 in width\. - Width: Listed dimensions are 18\.5 in long, 17\.5 in wide and 24\.5 in high\. (guide) - Three\-across evidence: Shown fitting three across beside a Britax Poplar convertible and a Willow S infant seat; with the cup holders fitted it is wider than the bare 17\.5 in width\. (review) - Setup caveat: In harness mode the base may hang over the front edge of the vehicle seat by up to 3 in, but no overhang at all is allowed in booster mode\. (blog) - Limits: - ### 4. [Clek Fllo](/products/ucp/modernnursery-com/4799010701412) (sold by modernnursery\.com) The Fllo was described as the narrower, lighter alternative to the Foonf, at 25 lb, easier to move and install, and suited to three\-across in mid\-size sedans\. Recall notice: Health Canada and Transport Canada, 2024\-11\-07: [Transport Canada Recall \- 2024716 \- CLEK](https://recalls-rappels.canada.ca/en/alert-recall/transport-canada-recall-2024716-clek) (safety notice, not a recall). The notice may cover only some serial numbers or dates of manufacture, which this listing does not show\. [What a match means](/recall-radar). - Width: The seat measures 27 in high x 16\.9 in wide x 12\.5 in deep rear\-facing, and 31 in high x 16\.9 in wide x 12\.5 in deep forward\-facing\. (guide) - Three\-across evidence: The Fllo was described as the narrower, lighter alternative to the Foonf, at 25 lb, easier to move and install, and suited to three\-across in mid\-size sedans\. (blog) - Setup caveat: Although narrow, the seat is long rear\-facing and may require the front passenger seat to move far forward; it may not suit compact cars\. (review) - Limits: - ### 5. [Maxi\-Cosi Kani 4\-in\-1 Convertible Car Seat](/products/ucp/modernnursery-com/14974430282094) (sold by modernnursery\.com) The three\-across fit is not guaranteed and depends on the vehicle model\. - Width: Maximum dimensions are 30\.25 in high by 19 in wide by 29 in deep; minimum dimensions are 19\.25 in high by 19 in wide by 23\.25 in deep; the seat weighs 23\.2 lb\. (guide) - Three\-across evidence: The three\-across fit is not guaranteed and depends on the vehicle model\. (guide) - Setup caveat: The maker warns that actual fit may vary and not all children will comfortably fit the full weight and height ranges\. (listing) - Limits: The retailer listing gives rear\-facing 5–40 lb and 19–40 in, forward\-facing 30–65 lb and 34\.4–49 in, high\-back booster 40–100 lb and 43\.4–52 in, and backless booster 40–100 lb and 43\.4–57 in; the maker's page instead gives forward\-facing as 22–65 lb, so the sources disagree on the forward\-facing lower limit\. (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 2026-10-31T06:58:48.083Z. ## Recall notices About the recall notices above: each matches a model named in a regulator's notice, as the index stood on 2026\-09\-25\. This listing is the brand and model a regulator's notice names\. Two AI models judged it so independently\. It does not mean the unit on sale is from an affected batch, that the store knew, or that the product is illegal where the store sells it; a US recall does not bind an Australian store\. The notice may cover only some serial numbers or dates of manufacture, which a listing does not show\. RoboTrunk never limits or blocks a purchase over a notice; read the notice and decide\. This page is published by RoboTrunk, a store built for shopping agents. 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