# What are the most compact 3-in-1 car seats with booster mode for small cars? — Verified Specification Comparison

> All specification data verified from official manufacturer documentation.

What are the most compact 3-in-1 car seats with booster mode for small cars?

## Products

### Chicco Fit3x ClearTex All-in-One Car Seat
```yaml
product: chicco-fit3x-cleartex-all-in-one-car-seat
brand: Chicco
price_gbp: 169.88
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
weight: 21.0
seat_width: 16.7 in
height_limit: 57 in
weight_limit: 100 lbs
harness_system: 12-position no-rethread harness
booster_backrest_height: 20 in
```

- **Price:** £169.88 [^1]
- **Summary:** The Chicco Fit3x ClearTex is a slim all-in-one car seat measuring 16.7 in wide and weighing 21 lbs. It supports rear-facing, forward-facing, and high-back booster use for children from 5 to 100 lbs, with ClearTex fabric, six recline positions, and fold-in CupFolders.
- **Ideal For:** It suits small cars because its 16.7 in ultra-slim width is designed for three-across seating, while its high-back booster mode accommodates children 40-100 lbs and 44-57 in tall.
- **Additional Sources:** [^2], [^3]

### Diono Radian 3RXT SafePlus 3-in-1 Convertible Car Seat
```yaml
product: diono-radian-3rxt-safeplus-3-in-1-convertible-car-seat
brand: Diono
price_gbp: 258.51
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
weight: 30.6
seat_width: 17
height_limit: 57.1
weight_limit: 120
harness_system: 5-point harness
```

- **Price:** £258.51 [^4]
- **Summary:** The Diono Radian 3RXT SafePlus is an all-in-one car seat that supports rear-facing, forward-facing harness, and high-back booster use from 4 to 120 lb. Its 17 in slim-fit design is made for fitting three car seats across, while SafePlus side-impact protection, an anti-rebound bar, and a 12-position headrest support growing children.
- **Ideal For:** It suits small cars because its 17 in slim-fit width is designed for three-across installation, while its 4-120 lb range and high-back booster mode allow one seat to serve from infancy through the booster years.

### Graco True3Fit LX 3-in-1 Car Seat
```yaml
product: graco-true3fit-lx-3-in-1-car-seat
brand: Graco
price_gbp: 206.08
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
seat_width: 16.5
height_limit: 49 or less; 43-57 in booster mode
weight_limit: 5-40 rear-facing; 26.5-65 forward-facing; 40-100 booster
harness_system: No-rethread 5-point harness
```

- **Price:** £206.08 [^5]
- **Summary:** The Graco True3Fit LX is a 3-in-1 seat that supports rear-facing, forward-facing, and highback booster use. It has a slim 16.5-inch width, a forward-facing belt lock-off, an anti-rebound bar, and a no-rethread harness, making it suitable for growing children and three-across installations.
- **Ideal For:** Its 16.5-inch width and highback booster mode from 40-100 lb make it a strong option for small cars and families needing a compact 3-in-1 seat.

---
## References & Sources
[^1]: Target, accessed 2026-09-13. https://www.target.com/p/chicco-fit3x-cleartex-ultra-slim-all-in-one-car-seat-black/-/A-94803559
[^2]: Chicco, accessed 2026-09-13. https://www.chiccousa.com/shop-our-products/car-seats/all-in-one/fit3x-cleartex-ultra-slim-all-in-one-car-seat/87179.html
[^3]: Instacart, accessed 2026-09-13. https://www.instacart.com/products/110752010-chicco-fit3x-cleartex-ultra-slim-all-in-one-car-seat-oat-1-each
[^4]: Raddl, accessed 2026-09-13. https://www.shopraddl.com/shop/babies-kids/car-seats/convertible-car-seats/radian-3rxt-safeplus-4-in-1-convertible-car-seat-copy/
[^5]: CarSeatSite, accessed 2026-09-13. https://carseatsite.com/true3fitlx/