Convertible car seats that fit three across in one back seat
Which convertible car seats are described as fitting three across in one back seat, and what are their widths, weights, and modes?
Graco SlimFit3 LX: Graco confirmed that three SlimFit3 LX seats fit three-across in a 2019-2021 Toyota RAV4 in several configurations, including all forward-facing, all rear-facing, and mixed modes. The seat is about 16.7 inches wide at the shoulders, with a base about 11.5 inches wide, making it one of the narrowest convertible seats tested. The reviewer measured the seat at about 18 pounds. The seat grows from a rear-facing harness to a forward-facing harness to a highback booster. Diono Radian 3R SafePlus: The retailer says the slim-fit design permits three seats across in most midsize vehicles. It measures 28.5 in high by 17 in wide by 16 in deep unfolded, and 11.5 in deep folded. The seat weighs 29.3 lb. The manual covers all-in-one use from 4 to 120 lb. Diono Radian 3QXT+ Luxury 3 Across All-in-One Car Seat: At 17 inches wide the seat is stated to fit three across in most midsize vehicles. The seat measures 16 inches deep by 17 inches wide by 28 inches tall. The store lists the seat weight as 34.2 lb; NHTSA lists 30.7 lb rear-facing, 28.3 lb forward-facing and 26.5 lb in booster mode for model 53000-NA-01, so the sources disagree on seat weight. DIONO Radian 3RX: This is an all-in-one convertible car seat with a steel core, designed for narrow three-across arrangements. The store says three seats will most likely fit when the rear row measures at least 51 inches (129.6 cm) between armrests; vehicle-belt installation may be necessary. Rear-facing use is listed for children weighing 5–50 lb (2.3–22.7 kg). DIONO Radian 3RXT: The store says three-across will most likely work where the rear row measures at least 51 inches (129.6 cm) armrest to armrest; all three may need seat-belt installation. The seat weighs 26.4 lb (11.97 kg). It is designed for rear-facing, forward-facing and booster use. Diono Radian 3QX Ultimate 3 Across All-in-One Car Seat: The seat's 17-inch width lets three Radian seats fit across a back seat with at least 51 inches between interior door handles. The 3QX is heavy at about 31.3 lb, making it hard to move between vehicles or remove for cleaning.
| Product | Why | Width | Weight | Modes | Three-across fit |
|---|---|---|---|---|---|
| 1. Graco SlimFit3 LX sold by albeebaby.com | Graco confirmed that three SlimFit3 LX seats fit three-across in a 2019-2021 Toyota RAV4 in several configurations, including all forward-facing, all rear-facing, and mixed modes. | The seat is about 16.7 inches wide at the shoulders, with a base about 11.5 inches wide, making it one of the narrowest convertible seats tested. review | The reviewer measured the seat at about 18 pounds. review | The seat grows from a rear-facing harness to a forward-facing harness to a highback booster. listing | Graco confirmed that three SlimFit3 LX seats fit three-across in a 2019-2021 Toyota RAV4 in several configurations, including all forward-facing, all rear-facing, and mixed modes. blog |
| 2. Diono Radian 3R SafePlus sold by anbbaby.com | The retailer says the slim-fit design permits three seats across in most midsize vehicles. | It measures 28.5 in high by 17 in wide by 16 in deep unfolded, and 11.5 in deep folded. guide | The seat weighs 29.3 lb. guide | The manual covers all-in-one use from 4 to 120 lb. manual | The retailer says the slim-fit design permits three seats across in most midsize vehicles. guide |
| 3. Diono Radian 3QXT+ Luxury 3 Across All-in-One Car Seat sold by megababiesusa.com | At 17 inches wide the seat is stated to fit three across in most midsize vehicles. | The seat measures 16 inches deep by 17 inches wide by 28 inches tall. listing | The store lists the seat weight as 34.2 lb; NHTSA lists 30.7 lb rear-facing, 28.3 lb forward-facing and 26.5 lb in booster mode for model 53000-NA-01, so the sources disagree on seat weight. listing | - | At 17 inches wide the seat is stated to fit three across in most midsize vehicles. guide |
| 4. DIONO Radian 3RX sold by anbbaby.com | This is an all-in-one convertible car seat with a steel core, designed for narrow three-across arrangements. | - | - | Rear-facing use is listed for children weighing 5–50 lb (2.3–22.7 kg). guide | The store says three seats will most likely fit when the rear row measures at least 51 inches (129.6 cm) between armrests; vehicle-belt installation may be necessary. guide |
| 5. DIONO Radian 3RXT sold by anbbaby.com | The store says three-across will most likely work where the rear row measures at least 51 inches (129.6 cm) armrest to armrest; all three may need seat-belt installation. | - | The seat weighs 26.4 lb (11.97 kg). guide | It is designed for rear-facing, forward-facing and booster use. guide | The store says three-across will most likely work where the rear row measures at least 51 inches (129.6 cm) armrest to armrest; all three may need seat-belt installation. guide |
| 6. Diono Radian 3QX Ultimate 3 Across All-in-One Car Seat sold by megababiesusa.com Recall notice: Health Canada and Transport Canada, 2024-11-25: Transport Canada Recall - 2024718 - DIONO (recall). The notice may cover only some serial numbers or dates of manufacture, which this listing does not show. What a match means. | The seat's 17-inch width lets three Radian seats fit across a back seat with at least 51 inches between interior door handles. | The seat's 17-inch width lets three Radian seats fit across a back seat with at least 51 inches between interior door handles. blog | The 3QX is heavy at about 31.3 lb, making it hard to move between vehicles or remove for cleaning. blog | - | The seat's 17-inch width lets three Radian seats fit across a back seat with at least 51 inches between interior door handles. blog |
Also cited in the text
- DIONO Radian 3RX, Purpose and construction: This is an all-in-one convertible car seat with a steel core, designed for narrow three-across arrangements. guide
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Written 2026-10-24T09:49:24.348Z.
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.
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