Car Seat Fitting & Installing Instructions

Fit & Installation

Just as every child is a different shape and size, so are vehicles. Certain car seats fit better in some vehicles more than others. What fits your neighbor’s vehicle may not fit yours. This is why we don’t encourage using second-hand seats.

It’s important you select a car seat that will accommodate your child’s growth needs, fits tightly in your vehicle and is easy to use. See the “Car Seats & Boosters” section for help choosing a car seat.

Below are tips on proper fit and installation of a car seat.


Consult your manual Always refer to the vehicle and child restraint owner’s manuals. Click on the links here to be taken to more information on that topic below:

  • Rear-facing seats for infants and toddlers up to age two
  • Forward-facing seats for preschoolers
  • Booster seats for children under 4 feet 9 inches tall
  • Seat belts for older children
  • Installing a car seat using seat belt
  • Installing a car seat using lower anchors and tethers: LATCH systems
  • Testing the tightness of a car seat installation
  • Common installation issues

How a child restraint should fit your child?

All car seats with a harness:

How a child restraint should fit your child?
  • The harness should lie flat and be snug on the child.
  • You should not be able to pinch any excess webbing.
  • Harness clip height
  • The harness clip should be positioned at armpit level.
  • Do not add padding or put heavy clothing on the child, creating extra space between the harness and child.

Infants – Rear-facing Car Seats

Infants – Rear-facing Car Seats
  • Check the instructions/seat label for the minimum and maximum weight limits allowed. Premature or low-birth-weight infants may need a seat built for their smaller size. Consult your manual
  • Children are five times safer riding rear facing until age two.* Most seats can be used rear facing beyond age one and 22 pounds. Consult your manual. *”Getting the Message Right,” Pediatrics, March 2008, 121:619-620

AAP Issues Updated Policy Statement

The American Academy of Pediatric updated policy statement provides 5 basic evidence based best-practice recommendations (5 steps) to optimize safety in the car for children from birth through adolescence.

AAP Issues Updated Policy Statement
  • 1. Infant-only or convertible CSS used rear-facing
    All infants and toddlers should ride in a rear-facing car safety seat (CSS) until they are 2 yrs of age or until they reach the highest weight or height allowed by the manufacturer of their CSS.
  • 2. Convertible or combination CSS used forward-facing
    All children 2 yrs or older, or those younger than 2, who have outgrown the RF weight or height limit for their CSS, should use a forward-facing CSS with a harness for as long as possible.
  • 3. Belt-positioning booster seat
    All children whose weight or height is above the forward-facing limit for their CSS should use a belt-positioning booster seat until the vehicle lap-and-shoulder belt fits properly, typically when they have reached 4 feet 9 inches in height and are between 8 and 12 years of age.
  • 4. Lap-and-shoulder vehicle seat belt
    When children are old enough and large enough to use the vehicle seat belt alone, they should always use lap-and-shoulder belts for optimal protection.
  • 5. All children younger than 13 years should be restrained in the rear seats of vehicles for optimal protection.

Click here to download the policy statement.

Learn more by reading the Technical Report on Child Passenger Safety by the Committee on Injury Poison & Violence Prevention.

  • The harness straps must come through the slots at or below the child’s shoulders. If the straps are above baby’s shoulders when in the lowest slots, then that car seat is not appropriate for your child. Consult your manual
  • Rear-facing car seats recline to prevent the baby’s head from falling forward and blocking their airway. Use the leveling device on the car seat if one is available—or a rolled towel—to assure the seat is properly reclined. Consult your manual
  • Once infants outgrow a carrier-style car seat, they should use a rear-facing convertible seat. Keep your child rear-facing until they reach the convertible seat’s rear-facing upper weight/height limits.
  • Do not move your child into a forward-facing seat until:

Preschoolers – Forward-facing Car Seats

Preschoolers – Forward-facing Car Seats
  • The harness must come through the slots at or above your child’s shoulders. The appropriate harness slot for a child can vary by manufacturer. Consult your manual
  • You will probably need to make some adjustments for the harness to fit properly whether the seat is used or new. Consult your manual
  • Convertible seats recline. Be sure it’s at the appropriate angle when used forward facing. Consult your manual
  • Children should ride forward facing in a seat with a harness until:
  • the child reaches the maximum height or weight limit for the seat, or
  • the harness straps are no longer at or above the child's shoulders.

Children Under 4 Feet 9 Inches Tall – Booster Seats

Children Under 4 Feet 9 Inches Tall – Booster Seats
Children Under 4 Feet 9 Inches Tall – Booster Seats 2
  • Booster seats must ALWAYS be used with a lap and shoulder belt.
  • A booster seat raises your child up so the adult lap and shoulder belt can be properly worn:
  • across the center of the shoulder and chest—not rubbing the neck, and
  • across the thighs—not over the abdomen.
  • Never allow the child to move the shoulder part of the belt under their arm or behind their back.
  • A child should use a booster seat until they outgrow it by height or weight.
  • In Washington, vehicles with only lap belts are exempt from the requirement to use a booster seat for children weighing more than 40 pounds.
  • When the child is not riding in their booster seat, make sure you buckle up the booster seat so it doesn't become a projectile in a crash.
  • Twinkie Physics Card for download and printing
  • Use Twinkie® Physics to understand proper seat belt fit and how a misplaced seat belt can injure a child in a crash. Download, print and fold the card on the right which also includes the 5-Step Test below to help decide when the seat belt fits properly.

Older Children – Seat Belts

If you can say YES to all five parts of the test below your child is ready to use a seat belt, which is usually around 8 years of age and 4 feet 9 inches tall:

Older Children – Seat Belts
  • 1. Does the child sit all the way back against the vehicle seat?
  • 2. Do the child’s knees bend comfortably at the edge of the vehicle seat without slouching?
  • 3. Does the lap belt stay on the top part of the child’s thighs, not over the abdomen?
  • 4. Is the shoulder belt centered on the chest and shoulder?
  • 5. Can the child stay seated this way for the whole trip?

If the answer is NO to any of these questions, or if your child puts the shoulder part of the seat belt under their arm or behind their back, your child still needs to use a booster seat. 

For example, Washington law requires children to ride in the back seat of the vehicle until their 13th birthday whenever it is practical to do so.

Choosing the safest seating location for your child

Choosing the safest seating location for your child
  • 1. Never place a rear-facing seat in front of an active front passenger airbag.
  • 2. Car seats must be installed on a vehicle seat that faces forward, not sideways or backwards.

The safest seating location is generally the center-rear seat, unless the child restraint is too wide for the location, or a pronounced hump or abutment compromises the fit of the child restraint.

Properly installing your car seat in your vehicle

Properly installing your car seat in your vehicle

To provide proper protection for your child a car seat with a harness must be held tightly into your vehicle with a seat belt or lower anchors.

If you cannot get a tight installation using the information in your owner's manuals and provided here, contact your local Child Passenger Safety Technician to schedule a car seat check-up where you can learn how to properly install your car seat.

Installing a car seat using a seat belt

Lap-only seat belts:

Many seat belts in the center-rear seating position work similarly to an airplane seat belt. When you buckle the seat belt and pull on the webbing tail the belt tightens and stays tight. This is called a lap-only belt with a locking latch plate. To install a car seat, feed the webbing through the appropriate seat belt path on the car seat, buckle and, while applying downward pressure on the car seat, pull the webbing tail to tighten.

Lap-shoulder belts work in one of three ways:

Lap-only seat belts
  • 1. Switchable retractor (most common): Slowly pull the lap-shoulder belt webbing out all the way. If when you retract the seat belt you hear a ratcheting sound (like a zipper) and the webbing is locked when you pull on it, you have a switchable seat belt. To install a car seat, feed the lap/shoulder belt through the proper belt path on the car seat and buckle. Pull the belt webbing all the way out to switch it into its locked mode. Apply downward pressure on the child restraint while steadily pulling the shoulder belt toward the retractor. NOTE: The seat belt will not hold the car seat in place unless you switch the seat belt into its locked mode.
Lap-shoulder belts work in one of three ways
  • 2. Locking latch plate: If, when you pull the lap-shoulder belt all the way out, it does not switch into a locked mode, then it’s likely the latch plate is what locks the seat belt. To install a car seat, feed the seat belt through the proper belt path on the car seat and buckle. Apply downward pressure on the child restraint while you pull the shoulder belt to tighten.

    It’s not very common (Volvo, Saab, Chrysler, Jeep), but you may also have a seat belt that locks by switching a button on the back of the latch plate. In either situation, the latch plate is what locks the car seat in tight.
  • 3. Vehicles manufactured before 1996 may need a locking clip, which comes with your car seat, because neither the retractor nor latch plate lock to hold a car seat in tight. Refer to your owner's manual for installation instructions.

Installing a car seat using lower anchors

Lower Anchors Tethers for Children: LATCH is a method of securing child restraints into a vehicle using two lower anchors and a tether, without using a seat belt.

Lower anchors: required in most vehicles beginning with 2002 models.

Installing a car seat using lower anchors
Lower Anchors Tethers for Children

Anchors are located where the upper and lower seat cushions meet. If not visible they can be located by a symbol on your seat cushions. Consult your manual

Lower anchors are not more or less safe than installing a car seat with a seat belt. Proper fit and installation is the key to safety.

Regulations require 11 inches/280mm between the two lower anchors. Due to this requirement, many vehicles do not permit a center-rear installation using lower anchors. If this is the case and the child restraint fits the center-rear seating position, it should be installed with the seat belt. Consult your manual

There are three types of lower anchor attachments on car seats. Consult your car seat owner’s manual for the proper way to attach to the lower anchors. Consult your manual

Push to latch with a rigid bar

Push to latch with a rigid bar: Clek, Baby Trend Latch-Loc

Push to latch with flexible webbing

Push to latch with flexible webbing: Britax, Chicco, Peg Perego, some Evenflo

Hook on with flexible webbing

Hook on with flexible webbing: Dorel, Graco, some Evenflo

Lower anchors are available for retrofit in only a few vehicles (Audi, VW, Volvo), check with the vehicle manufacturer.

check with the vehicle manufacturer.

Tethers: required in most vehicles beginning with model year 1999. Consult your manual

Tethering a forward-facing car seat is important because it reduces the forward movement of the car seat and child’s head during a crash.

Most vehicles with lower anchors also have a top tether anchor. Exemptions include sports cars and convertibles.

Do not confuse cargo anchors with tether anchors. You MUST check your vehicle manual. Consult your manual

Tether anchors can be retrofitted in many older vehicles. Call the Safety Restraint Coalition 1-800-282-5587 to learn more.

Testing tightness of a car seat installation

  • Check child restraint movement from side-to-side (in relation to the vehicle), not front to back.
  • Use one hand placed at the seat belt path. Push and pull using only the force of a firm handshake.
  • Up to one inch of side-to-side movement is acceptable.
  • The car seat should be level and not tipped to one side.

Common installation issues

The width of the child restraint must fit between the seat belt buckle and where the webbing comes out of the seat cushion. If the restraint is wider than the seating position, you will not be able to get a safe, tight fit. This frequently happens in the center-rear seat position.

With the driver’s seat positioned comfortably for the driver, a rear-facing car seat must be able to be installed in the back seat without the driver or front passenger seats pushing on the child restraint.

The seat belt webbing needs to be long enough to properly install the child restraint. Some smaller vehicles have difficulty accommodating large car seats due to the routing of the seat belt.

Some car seats that accommodate higher weight limits are significantly taller than regular seats and may not fit in smaller vehicles.

School Buses

The question: How can school buses possibly be safe, they’re big, there are few if any seat belts, children are small- if there was a crash the children would be hurled all around the inside of the bus? Explain to me why I should feel my child is safe riding a school bus.

The answer: Student transportation in the form of motorized vehicles has been around for just short of a hundred years. Statistically a child is safer being transported in a school bus than in a family vehicle. Consider this:

Annual school bus transportation statistics:

school bus transportation statistics
  • 450,000 public school buses
  • 24 million students transported
  • 4 billion miles traveled
  • 10 billion student trips
  • 20 billion times a student gets on or off

While catastrophic school bus crashes have occurred, they are rare events. Most school bus crashes are minor, and in most crashes involving passenger cars and light trucks, the school bus has the advantage of its larger size and weight.

As a result, many more people are killed or injured each year in vehicles that crash into school buses than are killed or injured in the school buses. It is difficult, if not impossible, to develop ways to protect school bus occupants in catastrophic crashes, such as those involving trains and heavy trucks.

The crash forces in those crashes are so great that any reasonable structural design cannot maintain the integrity of the vehicle, which is one critical component of occupant crash protection. (COPY: 2000 National Association of State Directors of Pupil Transportation Services.)

The question still exists: Why do school buses protect? This answer gets a little more complicated. Very often the basic explanation revolves around a term “compartmentalization,” comparing the students in a school bus to eggs in a carton. There is more to why a school bus protects.

Why do school buses protect

There are Federal standards that apply to school buses. As a result of the passage of the National Traffic and Motor Vehicle Safety Act of 1966 and the School Bus Safety Amendments of 1974, the National Highway Traffic Safety Administration, an agency of the U.S. Department of Transportation, has issued 36 Federal Motor Vehicle Safety Standards (FMVSS) which apply to school buses. 

These standards cover a range of components and systems, e.g., brakes, steering, glazing, lights, fuel system integrity, mirrors, heaters/defrosters, compressed natural gas containers, etc., and apply to all types of motor vehicles. Many of these federal standards have unique requirements for school buses.

The design and construction of today's school buses are a direct result of both the FMVSSs which apply to school buses and the guidelines adopted by the National Conferences on School Transportation, as well as some requirements that are unique to particular states or local school districts. While today's school buses do not look much different than their predecessors of 30-40 years ago, they are dramatically different. 

The improvements made to school buses in the past decades, as well as improvements in driver training, school bus maintenance, and school bus operating procedures, have been responsible for the outstanding safety record of school transportation. Well-trained school bus drivers avoid many crashes. (COPY: 2000 National Association of State Directors of Pupil Transportation Services.)

The following four standards are unique to school buses.

Why should I feel my child is safe riding in a school bus?

FMVSS No. 220, "School Bus Rollover Protection," which specifies the minimum structural strength of buses in rollover-type accidents;

FMVSS No. 221, "School Bus Body Joint Strength," which specifies the minimum strength of the joints between panels that comprise the bus body and the body structure;

FMVSS No. 222, "School Bus Passenger Seating and Crash Protection," which establishes requirements for school bus seating systems for all sizes of school buses, and provides minimum performance requirements for wheelchair securement/occupant restraint devices and establishes a requirement that wheelchair locations be forward facing; and

FMVSS No. 131, "School Bus Pedestrian Safety Devices," which requires school buses be equipped with an automatic stop signal arm on the left side of the bus to help alert motorists that they should stop their vehicles because children are boarding or leaving a stopped school bus.

FMVSS No. 222 brings us full circle to the term “compartmentalization.” Think back to your days on the good ol' school bus. Remember how those rigid green seats were wedged closer together than on even the cheapest no-frills airline? That's compartmentalization in action.

Sitting in "strong, closely-spaced seats that have energy-absorbing high seat backs," passengers are effectively protected from crashes. Of course, the method can't prevent all injuries, but the NHTSA argues it's the best possible solution. Several studies have shown seat belts would provide "little, if any, added protection."

So the initial question, Why should I feel my child is safe riding in a school bus? The answer is as simple as it is complex. The data available confirms and statistics support the fact that children are safe riding in school buses.

National Association of State Directors of Pupil Transportation Services

National Highway Traffic Safety Administration

Avatar of Kathy Warner

Kathy Warner

Kathy is a busy mother of two and a CPS technician for more than eight years. Her mission is to awaken parents to the importance of child passenger safety and show them the right practice. You can read more about her here

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