Car Rental Travel

Renting a Car in Guam with Kids | Child Seat Laws and Family Guide

(Updated )

Sort out child seats before a family road trip in Guam. Don’t choose by age alone: check your child’s height and weight, the seat maker’s limits, and whether your vehicle class can fit every seat you need. This guide covers everything from booking to driving off.

Key points
  • Under Guam law, kids younger than 4 ride in a federally approved car seat, and 4- to 11-year-olds shorter than 144 cm need a booster or a seat that fits them.
  • ONE’S offers three types: an infant seat (about ages 0–1), a child seat (about ages 1–4) and a junior/booster seat (about age 4 and older), at $5 per child per day.
  • You install the seat yourself, and child seats must go in the back seat.
  • Three child seats won’t fit across the back seat of AS-, A- and RV-class vehicles, so confirm a suitable vehicle class and availability before booking if you need three.
  • Age bands are only a guide: give each child’s age, height and weight when booking and choose a seat within its stated limits.

Family loading travel supplies into a dark gray Mazda3 in a Guam hotel parking area
Think about how many kids and how much luggage you’ll have when choosing a vehicle class and planning your days.

Guam’s child-restraint law

Guam law requires a child under age 4 to be secured in a federally compliant child passenger restraint used according to the manufacturer’s instructions. A child age 4 through 11 who is under 144 cm tall must use a booster seat or an appropriately fitting child restraint.

That doesn’t mean every child up to age 11 uses the same seat. Check your child’s age, height, and weight against the limits of the actual seat. Everyone else in the car must wear a seat belt.

Three seat types at ONE’S

ONE’S currently lists three options:

  • Infant seat: approximately ages 0–1
  • Child seat: approximately ages 1–4
  • Junior/booster seat: approximately age 4 and older

These age bands are only a guide. Provide each child’s age, height, and weight when booking and choose a restraint within its stated limits. The current terms list a fee of $5 per child per day. Confirm the latest price and availability in the booking process.

Rear-facing infant seat, forward-facing harness child seat, and booster seat displayed side by side
Choose according to the child’s size and the limits printed for the specific restraint—not age alone.

You install the seat yourself, in the back

At ONE’S, you install the seat yourself, and child seats must go in the back seat. Follow the labels and instructions on the seat and in the vehicle, then double-check the installation before driving.

  1. Park in a safe location and switch off the engine
  2. Secure the restraint in the rear seat exactly as instructed
  3. Make sure the installed seat doesn’t shift excessively
  4. Seat the child and check the harness or seat belt for twists and slack
Parent installing a child restraint in the rear seat of a parked dark gray Mazda3
Before driving, check the rear-seat attachment and the belt path.

Confirm the vehicle class when three seats are needed

ONE’S says three child seats won’t fit across the back seat of AS-, A- and RV-class vehicles. If you require three seats—or several restraints of different sizes—confirm a suitable vehicle class and availability before booking. Reservations are by class; a specific model or color cannot be guaranteed.

Family pre-drive checklist

  • Provide the age, height, and weight of every child
  • Confirm each restraint type, quantity, price, and availability
  • Confirm that the vehicle class can safely accommodate all seats
  • Keep drinks, snacks, spare clothes, and wipes accessible
  • Plan realistic driving times and rest stops
  • Never leave a child alone in a vehicle, even briefly
Parent checking a child's harness in the rear seat of a parked dark gray Mazda3
Before departure, remove twists and check the harness, buckle, and fit.

Frequently asked questions

Does every child age 11 or younger need a child seat?

Children under age 4 need a child restraint. Children age 4 through 11 need a booster or suitable child restraint when they are under 144 cm tall.

Will ONE’S staff install the seat?

No, you install it yourself. Put it in the back seat and follow the seat and vehicle instructions before you head out.

Can three child seats fit across the rear seat?

Not in ONE’S AS-, A- and RV-class vehicles. Space also varies by restraint type, so ask ONE’S which vehicle class can accommodate your combination before booking.

Summary

For a family rental in Guam, check the legal age and height thresholds and reserve a restraint suited to each child’s size. You install it in the back seat yourself and check the fit and harness before driving. If you need more than one seat, confirm which vehicle class works before booking.

Information checked September 13, 2026. Laws, prices, availability, and procedures may change. Review the current Guam code, ONE’S official website, and booking instructions before use.

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