How To Measure Linear Inches For Luggage: A Simple Guide

Posted by U.N. Luggage on Jul 24, 2025

Let’s face it: Figuring out airline luggage size restrictions can feel like solving a puzzle, especially when they toss around terms like “linear inches.” What are they measuring, and why does it matter?

At U.N. Luggage (Canada’s oldest luggage store, proudly serving travellers since 1940), we’ve helped thousands of customers avoid surprise fees and packing frustration. So we’re breaking it down in a simple, Canadian-friendly way.

This guide will walk you through what linear inches actually are, how to measure luggage properly, and tips for keeping your carry-on bags and checked luggage well within the airline limits, without sacrificing space or style.

What Are Linear Inches?

Linear inches refer to the total sum of your bag’s exterior dimensions: Length + width + height.

It’s the standard measurement airlines use to determine if your luggage fits within their size limits. While weight limits are also crucial, going over the size limit in linear inches is what often triggers those pesky oversized baggage fees.

For example: If your bag is 28" tall, 20" wide, and 10" deep, then: 28 + 20 + 10 = 58 linear inches.

Easy enough? Let’s dive deeper so you can measure your own luggage like a pro:

Step-By-Step Measurement Guide

Before you begin, place your suitcase on a flat surface and make sure it’s empty. Fully zipped. Upright. Ready to go.

Now you’ll measure three sides of the bag: Length, width, and height. And yes, wheels and handles count!

Length Measurement

Length is the longest side of your luggage when it’s lying flat on its back (usually from top to bottom). If you’re measuring a suitcase upright, it’s the vertical dimension.

• Use a measuring tape and go from the bottom of the wheels to the top of the carry handle (if fixed).
• Round up to the nearest half inch; most airlines aren’t dealing in decimals.

Width Measurement

Next up: Width. That’s the side-to-side dimension when your suitcase is standing upright.

• Measure across the widest part, including any protruding external pockets or zippers.
• If you’re using expandable luggage, measure it fully expanded.

Height Measurement

Now measure the depth, or the front-to-back height, when the suitcase is lying on its wheels.

• This includes handles, feet, or any bumper pads.
• Don’t forget curved areas; measure to the furthest edge.

Common Airline Requirements

Every airline has its own version of "standard size," and these size limits can vary slightly between carriers, especially when comparing domestic to international flights.

Domestic Flights

Most Canadian airlines, like Air Canada and WestJet, allow carry-on bags with a maximum of 21.5 x 15.5 x 9 inches, which equals 46 linear inches. Your checked luggage is typically limited to 62 linear inches.

Here’s a quick breakdown:

Always check the airline’s current policy before you pack, as it can change.

International Flights

International airlines follow similar limits, but they can vary more drastically. For example:

• Lufthansa and British Airways allow slightly smaller carry-on baggage.
• Southwest Airlines, known for its generous policies, still uses a 62 linear inch rule for checked bags.

Size limits for carry-ons on international flights are often around 45 linear inches, but the weight limit may be stricter (7kg is common).

Pro tip: If you’re taking multiple flights with different airlines, always pack to meet the most restrictive policy.

Tools Needed For Accurate Measurement

You don’t need much to measure luggage, just a little time and the right tools:

• Soft measuring tape: Best for flexible bags or duffel bags
• Rigid measuring tape: Ideal for structured luggage or hard cases
• Flat surface: Use the floor or a low table for accurate readings
• Luggage scale (optional): Helps keep you under airline weight restrictions, especially with checked baggage

Tips For Staying Within Limits

Here are a few tricks to help you stay within luggage size limits and avoid those dreaded baggage fees:

1. Watch The Wheels

Always include wheels and handles in your measurements. Some brands list dimensions without them, but the airline won’t. Even a couple of extra inches can push your bag into oversized territory.

2. Avoid Overpacking Expandable Luggage

It might still zip closed, but expanded bags can easily exceed carry-on or checked luggage limits. Check dimensions again after packing, especially if you've used the expansion zipper.

3. Go Soft-Sided

Soft materials like canvas or nylon give you more flexibility than hard shells when it comes to stuffing and squeezing into overhead bins. They’re also more forgiving if you need to squish your bag under the seat.

4. Know What Counts As A Personal Item

Most airlines allow one carry-on and one personal item (like a backpack, purse, or laptop bag). Personal items must fit under the seat in front of you, usually under 17 x 13 x 6 inches.

5. Use Packing Cubes

Packing cubes don’t reduce your bag’s size, but they can help distribute weight better and reduce bulk, meaning less risk of accidentally going over.

6. Test Before You Travel

Once packed, set your bag on a flat surface and re-measure to confirm it still meets airline requirements. It's easy to overlook how much a few extra layers or souvenirs can affect your final dimensions, particularly with soft-sided or expandable luggage.

7. Choose The Right Luggage For The Job

Consider investing in a suitcase specifically designed for carry-on luggage or international travel. Many brands now create bags that intentionally stay below most airline size limits, giving you peace of mind at the gate and more room for shopping on the way home.

Double-Checking Your Measurements

Before you leave for the airport, double-check the total linear inches of your luggage. This simple step can save you time, stress, and unexpected oversized baggage fees at check-in. You can do this by following these simple steps: 

1. Add the length, width, and height together (including wheels and handles).
2. Compare your measurement to the airline’s published limits.
3. Weigh your bag to ensure it’s also under the maximum weight.

If you’re on the edge, play it safe. Airlines don’t hesitate to tag oversized luggage and charge you extra.

And remember, some smaller carriers (especially low-cost international ones) have tighter limits for carry-ons and checked bags. Don’t assume all airlines are the same!

Why This Matters

Oversized baggage fees can run anywhere from $50 to $200, depending on the airline and route. That’s money better spent on dinner when you land (or an upgrade to your next bag).

Accurate measurements help you:

• Pack more efficiently
• Avoid last-minute surprises at the gate
• Choose the right luggage for each trip
• Stay within airline size and weight restrictions
• Travel with confidence

Contact U.N. Luggage Today

Need help picking the perfect carry-on luggage or finding a sleek new checked bag that meets size limits for most airlines? That’s what we’re here for.

At U.N. Luggage, we specialize in premium travel gear, expert packing advice, and personal service that big-box stores just can’t match. Our team knows which brands and styles work best for frequent fliers, leisure travellers, and everyone in between.

Contact U.N. Luggage today or visit our Winnipeg store, and let’s make sure your next trip starts off on the right foot (and with the right suitcase).