Carry-on bag size: how to measure before you fly

Carry-on bag size on Qantas is set by adding three measurements together, and the most common limit on its domestic flights is 115 cm in total. That is the length, height and depth of the bag, and the bag must also weigh no more than 7 kg. This guide shows you how to measure, what the main Australian airlines published by April 2018, and how to avoid a fee at the gate.

Sources for this section: Qantas, Carry-on baggage (page as archived on 2 April 2018).

How the limit is worked out

Qantas does not give one single size. It gives a total. Its page says total dimensions are measured by adding together the length, height and depth of the bag. A bag of 56 cm by 36 cm by 23 cm adds up to 115 cm. A smaller bag of 48 cm by 34 cm by 23 cm adds up to 105 cm.

That means the three numbers on a luggage tag are not the whole story. Add them up and compare the sum with the airline's limit. Weight is a second, separate limit. A bag can fit the size rule and still be too heavy.

Sources for this section: Qantas, Carry-on baggage (page as archived on 2 April 2018).

What Qantas allows

The Qantas page, as it stood in early April 2018, listed the rules below. The weight limit is 7 kg per piece in every case.

On top of this, Qantas lets you carry one small personal item. It names a handbag, a laptop, an overcoat and a small camera as examples. Infants do not get a carry-on allowance, but food and nappies for the flight can travel in addition to the adult's allowance.

The page also says your bag must fit under the seat in front of you or in an overhead locker. If a bag meets the size rules but staff think it is not safe to carry on, they may ask you to check it in.

Sources for this section: Qantas, Carry-on baggage (page as archived on 2 April 2018).

What Jetstar and Virgin Australia published

Jetstar changed its rules in late 2014. From 25 November 2014, economy passengers on its Starter, Starter Plus and Starter Max fares could bring one main item of up to 56 cm by 36 cm by 23 cm, plus one other small item. The two items together could weigh no more than 7 kg. Before that change the limit was 10 kg.

The same news report said Virgin Australia, Air New Zealand, Scoot and AirAsia X also had a 7 kg carry-on limit in economy at that time. It noted that Qantas allowed two bags of up to 7 kg each on most domestic flights. Rules can change, so treat a report from 2014 as a guide only and read each airline's own page before you fly.

The important point for planning is the weight. Across these carriers, 7 kg was the figure to pack to. Jetstar counts your main bag and your small item together, while Qantas counts each piece on its own.

Sources for this section: The Sydney Morning Herald Traveller, Cabin bag crackdown: Jetstar to reduce cabin baggage limit to seven kilograms from 10 kilograms (28 October 2014).

How to measure your bag

Use a soft tape measure and follow these steps at home.

1. Empty and zip the bag. Pack it as you will fly, then close it. A stuffed bag bulges and is bigger than an empty one.
2. Measure the height. Go from the floor to the top of the bag, including wheels and the top of any fixed handle.
3. Measure the width. Take the widest point across the front.
4. Measure the depth. Take the thickest point from front to back, including side pockets and any bulge.
5. Add the three numbers. Compare the total with your airline's limit, for example 115 cm for a Qantas domestic flight.

Measure the outside of the bag, not the space inside. A bag sold as a "carry-on" in a shop may still be over an airline's limit once the wheels and pockets are counted. If you are close to the limit, choose a smaller bag.

How to weigh your bag

Weigh the packed bag, not the empty one. A bathroom scale works. Stand on it with the bag, then stand on it alone and subtract. A small hand-held luggage scale also works.

Remember that the 7 kg limit usually counts everything in the bag, including a laptop and chargers. Qantas treats your personal item as extra to the bag allowance, but check how your own airline counts it. On Jetstar, the small item is part of the 7 kg total.

If you are over, move heavy items such as books, shoes and toiletries into your coat pockets or your personal item where the rules allow. Better still, pack less.

Avoiding gate fees

An oversize or overweight bag can be sent to the hold at the gate, and that can cost money. When Jetstar tightened its rules in 2014, it said a bag moved to the hold at the gate would cost A$50 on domestic flights and A$160 on international flights. Those were 2014 figures, and they may have changed since, so check the current fee when you book. Check-in fees paid at booking were lower than airport prices at that time.

Three habits keep you clear of fees.

• Measure and weigh at home, a few days before the trip.
• Look at the airline's own page when you book, then once more just before you leave for the airport.
• Keep your essential medication and valuables in the bag you carry on, as Qantas advises, and keep it light, because airport walks can be long.

If your bag is too big for the cabin, the cheapest answer is usually to buy checked baggage when you book, rather than pay at the airport.

Sources for this section: The Sydney Morning Herald Traveller, Cabin bag crackdown: Jetstar to reduce cabin baggage limit to seven kilograms from 10 kilograms (28 October 2014); Qantas, Carry-on baggage (page as archived on 2 April 2018).

Sources

1. Qantas, Carry-on baggage: qantas.com (archived 2 April 2018).
2. The Sydney Morning Herald Traveller, Cabin bag crackdown: Jetstar to reduce cabin baggage limit to seven kilograms from 10 kilograms, 28 October 2014: traveller.com.au.