How to Measure Your Suitcase Against an Airline's Checked-Baggage Size Limit

Most travellers check the weight of a suitcase and never measure it. The weight limit is the one everybody knows about. The size limit sits further down the airline's baggage page, and it is not the number printed on the swing tag. A case sold as "28-inch" tells you roughly how tall the shell is, not whether the packed case, wheels and handle included, sits inside the airline's limit. This post shows how that limit is worked out, how to measure your own case in ten minutes, and where people go wrong.

We sell luggage, so we are not neutral. Every VOX figure below is copied from the published specifications on our own shop pages, and where those pages say nothing we say so rather than guess.

The short answer

• Many airlines limit the total, not each side. Singapore Airlines, for example, says the sum of the length, width and height of each checked bag must not exceed 158 cm (62 inches). Your own airline may use a different number, so read its page for your ticket.
• Measure the whole bag, not the shell. Include the wheels underneath, the handle and any side or top grips, and measure the case packed, not empty.
• An expandable case is measured the way you fly it. If you unzip the expansion for the trip home, the depth changes and so does the total.
• Size and weight are two separate limits. A bag can pass one and fail the other.

What the rule actually says

The wording on Singapore Airlines' checked baggage page reads: "The sum of length, width and height of each checked baggage must not exceed 158cm (62 inches)." That is a total of three measurements, not three separate limits. A bag can be a little long and still pass, as long as it is slim enough to bring the total down. It can also be unremarkable in each direction and fail because all three are generous.

Other airlines publish their own figures, and some state them differently, as a limit per side or as a total that depends on the fare. We have not compared them for this post, and we are not going to quote a number we have not read on the airline's own page. The method below works for any airline that states a total. If yours states a limit per side instead, measure the same three directions and compare each one against its number.

How to measure a suitcase for the total

1. Pack it first. A soft or expandable case grows when it is full, and the packed bag is what the airline measures. An empty case gives a best-case figure.
2. Stand it upright on a hard floor with the handle fully retracted, and use a tape measure rather than judging by eye.
3. Height: from the floor, under the wheels, to the top of the case. If a top grip sticks out above the shell, measure to the top of the grip.
4. Width: across the widest point, which may be the shell, a side handle or a hard corner.
5. Depth: across the thickest point, front to back, including any bulge from a packed front pocket or an expansion gusset that has been opened.
6. Add the three numbers and keep the total on your phone next to your booking, so you do not have to remember it at the counter.

Do it once at home, not at the airport. At home, a total that is two centimetres over is a decision you can make in your own time, by taking out a bulky item or by not expanding the case. At the counter it is not.

A worked example, with a made-up case

This is an illustration with invented numbers, not a VOX case. Say a packed case measures 76 cm tall including the wheels, 50 cm wide and 30 cm deep. The total is 76 + 50 + 30 = 156 cm, which is under a 158 cm limit. Now open the expansion for the trip home and the depth becomes 35 cm. The total is 76 + 50 + 35 = 161 cm, which is over it. The same bag, on the same airline, goes from passing to failing because of one zip. That is why we say to measure the case the way you will actually fly it.

What goes wrong most often

• Measuring the shell and forgetting the wheels. Wheels add height. A listing that gives a height without saying whether it includes the wheels has not given you the number you need.
• Trusting the inch label. "28-inch" is a size class, and different makers put different external sizes behind it, which is why the centimetres matter. We work through this in how big a 28-inch suitcase really is, in litres and kilos.
• Measuring empty and flying full. A packed front pocket or a case stuffed past its shape adds depth.
• Forgetting the return leg. Most people buy something. A case that was comfortably under the limit on the way out is the one that has been expanded on the way back. We look at that trade in is an expandable suitcase worth the extra 5 cm.
• Checking one airline and flying three. On a trip with several legs, each operating carrier sets its own rules. See when your baggage allowance changes mid-journey.
• Mixing up size and weight. A bag that passes the tape measure can still be overweight, and the other way round. The weight side is in avoiding the overweight surprise at check-in.

Trains have their own number

An airline's limit is not the only one. On the Tokaido, Sanyo, Kyushu and Nishi Kyushu Shinkansen, JR Central uses the same length-plus-width-plus-height method with a different line, and a bag over it needs a reserved seat with an oversized baggage area. The details, and what happens if you board without one, are in taking a big suitcase on the Shinkansen. The habit is the same: measure with the wheels and handle, measure it packed, and write the total down.

What VOX publishes, and what it does not

These are the manufacturer's external figures for the two VOX cases, as published on our shop pages:

• The VOX Magnesium Aluminium Voyage Box (S$590 at the founders' price, S$690 retail): external 70 × 45.5 × 27 cm.
• The VOX RPET Voyage Box (S$290 at the founders' price, S$390 retail): external 69 × 50 × 30 cm, and 35 cm deep when expanded.

What we have not published is an overall size with the wheels and the handle included, so we have no total to give you, and we are not going to add the numbers above and call the result a fit. We also make no claim about any particular airline's limit. If an exact measurement matters for your flight, email hello@voxjourney.com and we will measure the actual case for you. Whatever case you own, a tape measure in your own hallway gives you a better answer than any listing.

Before you leave for the airport

1. Find the size rule on your airline's baggage page for your fare and route, and note whether it is a total or a limit per side.
2. Measure the packed case, wheels and handles included, and add it up.
3. If you use an expansion, measure it expanded, because that is how it will fly home.
4. Weigh the case too. Size and weight are checked separately.
5. Keep the numbers on your phone, with a photo of the tape against the case.

The first-use checks for a new case, including the lock, the zips and the wheels, are in your new suitcase has arrived: what to check before its first trip.

Not sure what to check for your airline? Message us on WhatsApp, tell us your airline and your usual trip, and we will tell you honestly what we can and cannot say about it.