How to Adjust the AVARO Infant Car Seat Harness

Posted by Angie Hough on March 25, 2026

Adjusting the harness correctly helps keep your baby properly positioned in the AVARO infant car seat during vehicle travel.

AVARO is approved under UN R129 / i-Size for rearward-facing infant vehicle travel from 40 to 87 cm and up to 13 kg. Harness fit should be checked before every journey and adjusted as your baby grows.

See how to adjust the AVARO infant car seat harness.

Quick Answer

To adjust the AVARO harness correctly:

Place your baby fully back in the car seat.
Adjust the headrest so the harness sits correctly for your baby’s size.
For rearward-facing use, position the shoulder straps at or just below your baby’s shoulders.
Fasten the buckle securely.
Tighten the harness until it is snug against your baby’s body.
Check that the straps lie flat and are not twisted.

A correctly fitted harness should sit close to the body, with no loose slack and no twisted straps.

Why Harness Fit Matters

The harness is part of the infant car seat’s restraint system.

If the harness is too loose, twisted or positioned incorrectly, it may not perform as intended during vehicle travel.

Correct harness use helps with:

Keeping your baby positioned correctly in the seat.
Maintaining the intended restraint path across the shoulders and body.
Supporting proper fit as your baby grows.
Making the pre-journey safety check more consistent.

This guide focuses on the AVARO infant car seat harness. The LUNO stroller harness uses a different adjustment system and should be checked separately according to the stroller manual.

Before You Start

Before adjusting the harness, make sure your baby is positioned correctly in the seat.

Place the car seat on a stable surface or ensure it is correctly locked onto the ISOFIX base.
Place your baby fully back in the seat.
Make sure your baby’s back and bottom are supported by the seat shell.
Remove bulky clothing that may prevent a snug harness fit.
Check that no blankets, toys or accessories interfere with the harness.
Use only the approved AVARO insert and components according to the manual.

Do not add unapproved inserts, padding, strap covers or accessories to the car seat.

Step-by-Step Harness Adjustment

1. Position Your Baby Correctly

Place your baby fully back in the car seat.
Check that their back and bottom are properly supported.
Make sure the baby is centred in the seat.

2. Adjust the Headrest

Adjust the headrest height to suit your baby’s size.
The harness height adjusts with the headrest.
For rearward-facing use, check that the harness sits at or just below shoulder level.

The headrest should support your baby correctly without pushing the head forward or leaving the harness too high above the shoulders.

3. Position the Shoulder Straps

Lay the shoulder straps flat over your baby’s shoulders.
Check that the straps are not twisted.
Make sure the straps sit evenly on both sides.

4. Fasten the Buckle

Bring both buckle tongues together where required.
Insert them into the central buckle.
Push until the buckle clicks securely into place.
Check that the buckle is properly fastened before tightening.

5. Tighten the Harness

Pull the adjustment strap at the front of the car seat.
Tighten until the harness sits snugly against your baby’s body.
Check that there is no loose slack around the shoulders or hips.
Do not over-tighten to the point of discomfort.

6. Check the Fit

The harness should lie close to your baby’s body.
The straps should remain flat and untwisted.
You should not be able to pinch excess strap at the shoulder.
The buckle should remain securely fastened.
Your baby should remain properly positioned in the seat.

Correct Shoulder Strap Position

For rearward-facing infant car seat use, the shoulder straps should sit at or just below the baby’s shoulders.

Check:

The headrest is adjusted to the correct height.
The shoulder straps are not above the shoulders.
The straps lie flat over the shoulders.
The harness does not twist, gap or sag.

If the shoulder straps are too high or too low, adjust the headrest and check the harness position again before travelling.

Clothing and Harness Fit

Bulky clothing can make a harness look tight while leaving hidden slack underneath.

Before driving:

Avoid thick jackets or bulky layers under the harness.
Use thinner layers where possible.
Tighten the harness against the baby’s body, not against bulky clothing.
Use blankets over the secured harness if warmth is needed, rather than under the straps.

Always recheck the harness fit when clothing thickness changes.

Newborn Insert and Harness Fit

The AVARO newborn insert is used according to the product manual to support smaller babies during the early stage of use.

Use the insert only as instructed by the AVARO manual.
Do not add extra padding or unapproved inserts.
Check that the insert does not create harness slack.
Remove or adjust the insert only when instructed by the manual and when your baby’s fit requires it.

The harness must still sit snugly and correctly when the insert is being used.

Common Harness Mistakes to Avoid

Leaving the harness too loose.
Allowing shoulder straps to twist.
Using bulky clothing under the harness.
Positioning the shoulder straps above the shoulders for rearward-facing use.
Adding unapproved padding or accessories.
Forgetting to adjust the harness as your baby grows.
Driving before checking that the buckle is fully fastened.

Before Every Journey

Before driving, complete a quick harness and seat check.

Check that AVARO is correctly locked onto the ISOFIX base.
Check that the ISOFIX base indicators show correct installation where applicable.
Check that the support leg is positioned correctly.
Check that your baby is sitting fully back in the seat.
Check that the harness is flat, snug and untwisted.
Check that the buckle is securely fastened.

Correct base installation and correct harness fit both matter. One does not replace the other.

Important Safety Notes

Always use the harness when your baby is in AVARO.
Always use AVARO rearward-facing only.
Never leave straps loose or twisted.
Adjust the harness as your baby grows.
Do not add unapproved inserts, padding or accessories.
Always confirm the buckle is securely fastened.
Ensure the harness is snug before every journey.
Do not use AVARO once your baby has outgrown the approved range of 40 to 87 cm or 13 kg.

Practical Tips for Parents

Check the harness before every trip.
Recheck the fit when clothing thickness changes.
Adjust the headrest as your baby grows.
Look for twisted straps before fastening.
Use the pinch check at the shoulder to check for excess slack.
Ask for help if you are unsure whether the harness is positioned correctly.

Frequently Asked Questions

How tight should the AVARO harness be?
It should be snug against your baby’s body, with no loose slack and no excess strap to pinch at the shoulder.

Can the straps sit above the shoulders?
For rearward-facing infant car seat use, the shoulder straps should sit at or just below the shoulders.

Do I need to adjust the harness often?
Yes. Adjustments may be needed as your baby grows or when clothing thickness changes.

Can my baby wear a thick jacket under the harness?
Avoid bulky clothing under the harness because it can create hidden slack. Use thinner layers and place warmth over the secured harness if needed.

Does the stroller harness adjust the same way?
No. This guide covers the AVARO infant car seat harness. The LUNO stroller harness uses a separate adjustment system.

Explore the Full System

AVARO forms part of selected Mimi LUNO travel system setups. Compare the available configurations to choose the setup that fits your family’s routine.

Explore the Mimi LUNO Range

Important Note for Parents

This guide provides general harness adjustment support for the AVARO infant car seat.

It does not replace the AVARO manual, product-specific instructions, vehicle information, formal safety standards or professional guidance where needed.

Always use AVARO only for its intended context: rearward-facing infant vehicle travel from 40 to 87 cm and up to 13 kg, according to the product manual.

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