Car Seat Guide Calculator
Find the right car seat type for your child based on their age, weight, and height.
Covers rear-facing, forward-facing, and booster seats.
Car seat sizing matches a child’s weight, height, and age to the correct car seat category and installation method. Using the wrong seat — or improperly installing the right one — is the leading cause of child injury in vehicle crashes.
Seat Categories by Size:
| Seat Type | Child Weight | Child Height | Age |
|---|---|---|---|
| Infant (rear-facing only) | Up to 13 kg (30 lbs) | Up to 83 cm (32.5 in) | Birth–12 months |
| Convertible (rear-facing) | Up to 18–23 kg | Up to 110 cm (43 in) | 0–2+ years |
| Convertible (forward-facing) | 9–29 kg (20–65 lbs) | Up to 127 cm (50 in) | 2–7 years |
| Booster seat | 18–36 kg (40–80 lbs) | 95–145 cm | 4–12 years |
| Seat belt only (vehicle belt) | 36+ kg and 145+ cm | Over 145 cm | 8–12+ years |
Weight and Height Check Formula:
Child is ready to advance when EITHER:
- Weight exceeds the seat’s rated maximum, OR
- Head is within 2.5 cm (1 inch) of the top of the seat shell
Worked Example:
Child: 3 years old, 16 kg, 95 cm tall.
- Not yet at convertible rear-facing weight limit (18–23 kg)
- Head below top of shell
- Keep rear-facing — this is the safest position even at age 3
At 18 kg or when head reaches limit: switch to forward-facing with 5-point harness.
LATCH Weight Limit:
The LATCH system (Lower Anchors and Tethers for Children) is rated to child + seat weight of 29 kg (65 lbs). Above this, use the seatbelt to install even if LATCH hardware is present.
Practical Tips:
- Rear-facing is always safer until the child outgrows the rear-facing weight/height limit
- Harness straps should be snug: you should not be able to pinch the webbing at the shoulder
- Get a certified car seat technician to check your installation — errors are extremely common