Booster cushions under R129: the 125 cm rule explained
Backless booster cushions are allowed under R129 — but only from 125 cm, and only if they lift the child high enough. Here’s how the rule works.
The rule
A booster cushion may not be approved, or declared for use, below a stature of 125 cm (§6.1.3.6). High-back booster seats start at 100 cm and must give side protection up to 135 cm — cushions have no backrest and are not tested in lateral impact (§7.1.3(b)).
The head-height test
A cushion must place the top of the child’s head at or above a horizontal plane 770 mm above the Cr axis of the test bench. A measuring device on a simulated bench reads the sitting height the cushion provides, and Table 3 converts it into the smallest stature the cushion may be declared for:
| Sitting height (cm) | 66.2 | 67.9 | 69.7 | 71.6 | 73.6 | 75.9 |
|---|---|---|---|---|---|---|
| Minimum stature (cm) | 125 | 130 | 135 | 140 | 145 | 150 |
Values in between are interpolated and rounded up: 70.1 cm gives 136.05 cm, so the cushion cannot be declared below 137 cm. A thin cushion therefore ends up with a higher minimum stature.
Staying under the child
A 250 ± 5 N pull test with a lower-torso body block checks the cushion is not pulled out from under the child or out of the belt (§7.1.3.7). Belt guidance rules for the lap belt (through the pelvis, angles over 10°) apply as for all non-integral seats (§6.2.1.5).
Labels
Cushions carry a label of at least 60 × 40 mm showing the lower stature limit; if the cushion is part of a booster seat with a removable backrest, the label is visible only in cushion mode (§4.8.5), and the backrest itself carries a product label (§4.11).
More: R129 booster seats and cushions.
Can a 6-year-old use a booster cushion?
Only if they are at least as tall as the cushion’s declared minimum, which is never below 125 cm under R129. Most 6-year-olds are shorter, so a high-back booster seat is the R129 option.
Guidance only. Check the authentic UN/ECE text and your Technical Service before relying on any requirement for approval.