How to Measure Your Carry‑On Bag (Correctly)

By Carry‑On Checker Editorial •

At a glance: Measure external length × width × height (wheels and handles included). If an airline uses a single “linear” limit, add L + W + H.

What counts toward size

Unless your airline states otherwise, use external dimensions—that means wheels, side pockets, and the top handle are included. Telescoping handles count at their lowest stored position.

Tools you’ll need

Step‑by‑step measurement

  1. Prepare the bag — Empty or pack lightly so bulges don’t distort measurements. Close all zippers.
  2. Length (L) — With the bag upright, measure from the floor to the topmost point (usually the top handle housing).
  3. Width (W) — Measure the side‑to‑side distance at the widest point (include side pockets).
  4. Height (H) — Rotate the bag and measure front‑to‑back depth at the thickest area (include wheels).
  5. Record the largest values — Soft‑sided bags compress, but use the uncompressed dimensions for policy comparisons.
Tip: If your bag has rounded corners, measure to the farthest edge, not the seam. Airline sizers use straight edges.

Linear dimensions (L + W + H)

Some airlines publish a single “linear” maximum (e.g., L + W + H ≤ N). Add your three measurements and compare the sum to the airline’s limit. If your sum is equal to or below the posted maximum, you’re within policy.

Personal item sizing

Under‑seat items are smaller than carry‑ons and must fit beneath the seat in front of you. Limits vary by airline and aircraft. Check your airline’s posted size and use the same method above to measure.

Record & check your measurements

MeasurementInchesCentimeters
Length (L)____ in____ cm
Width (W)____ in____ cm
Height (H)____ in____ cm
L + W + H____ in____ cm

Switch units in the checker if needed—conversions use 1 inch = 2.54 cm.

Open the Carry‑On Checker

Common mistakes to avoid

Questions or corrections? Email customerservice@carryonchecker.net.

Measuring irregular shapes

Not all bags are perfect rectangles. Duffels taper toward the top, backpacks bulge when stuffed, and expandable suitcases can add an inch or two of depth when you unzip the expansion gusset. To capture these nuances, identify the bag’s farthest points in each direction. When measuring height, include molded handles and any protruding feet. For width and depth, run your tape around side pockets and wheels. If your bag has an expandable section, measure both with the expansion closed and open—and plan your packing around the smaller figure.

Why precise measurements matter

Gate sizers are unforgiving; if your bag doesn’t slide into the metal frame without force, staff may insist on checking it. Product tags and retailer listings often advertise internal packing dimensions, not the external size the airline cares about. Even a one‑inch overage can be the difference between sailing on and waiting at baggage claim. Accurate measurements let you compare apples to apples when reading airline policies and avoid the stress of last‑minute repacking at the airport.

What if my bag is slightly over?

If your L × W × H sum is a half‑inch or a couple centimetres over an airline’s limit, consider the risk. Some carriers allow minor leeway, while others enforce strict measurements. You can mitigate border‑line cases by packing less so your bag compresses, choosing a softer bag that can squeeze into a sizer, or selecting a lower‑profile personal item to free overhead volume. When in doubt, size down; travel is stressful enough without worrying whether your roller will be tagged.

Additional FAQs

Do soft bags get a pass? Soft‑sided bags can compress into sizers more easily, but they must still fit without force. Hard‑sided suitcases offer more protection but have zero flexibility.

Does compression matter? Compression straps and cubes help keep dimensions consistent. But remember: airlines measure the bag itself, not its packed contents.

Should I pack with the bag partially collapsed? Some soft duffels have fold‑over tops that add height when stuffed. Measure the bag fully loaded to understand its real footprint.

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