Measure length, width, and height with a tape measure, then add them together to find the total inches — that's what airlines and baggage fees use
Luggage dimensions are the three measurements of your bag: length (longest side), width (side to side), and height (top to bottom). You measure each one in inches or centimetres, then add all three numbers together to get your total linear inches — the single number that airlines use to decide whether your bag fits in the overhead bin or counts as a carry-on, and whether you pay an oversized baggage fee.
The process takes five minutes and a tape measure. Most luggage tags and airline websites list the maximum allowed dimensions, so you need to know your bag's exact measurements before you book or pack.
Key Takeaways
- Measure the length, width, and height of your bag at its widest points, then add the three numbers to get total linear inches.
- Measure from the outside of the bag, including wheels, handles, and pockets that stick out.
- Airlines enforce dimension limits differently — some measure carry-on bags strictly, others only check checked bags, so look up your airline's policy before you pack.
- A standard carry-on bag is usually around 22 × 14 × 9 inches (45 linear inches), but this varies by airline.
- If your bag is close to the limit, measure it when it is fully packed, because a stuffed bag may be slightly larger than an empty one.
What you need to measure luggage
You need a tape measure — cloth, metal, or plastic all work equally well. A ruler works if your bag is small, but a tape measure is faster for larger suitcases. You also need to know which airline you are flying with, because dimension limits vary.
Measure your bag when it is empty and sitting on a flat surface. If you are worried about how it will fit when packed, measure it again after you have packed it — a full bag can be slightly larger than an empty one, especially if the fabric stretches.
How to measure length, width, and height
Length is the longest side of the bag. Place the tape measure at one end and stretch it to the other end, running along the longest edge. Write down the number in inches.
Width is the measurement from left to right when the bag is facing you. Measure across the widest part of the bag from one side to the other. This is usually the depth of the bag — how far it sticks out from front to back.
Height is the measurement from the bottom to the top. Measure from the lowest point of the bag (including wheels if it has them) to the highest point (including the handle if it extends above the bag).
Write all three numbers down. Then add them together. If your bag measures 24 inches long, 16 inches wide, and 10 inches high, your total linear inches is 24 + 16 + 10 = 50 inches.
Measuring bags with wheels, handles, and pockets
Include wheels, handles, and any pockets or straps that stick out from the bag. Airlines measure the overall footprint of what you are bringing, not just the fabric box. If your rolling suitcase has wheels that add 1 inch to the height, measure from the bottom of the wheels to the top of the handle.
Soft-sided bags with expandable pockets are trickier. Measure them in their normal, non-expanded state — the way you would actually carry them. If the pockets are zipped closed, measure the bag as it sits. If you plan to use the expansion, measure with the pockets expanded.
Why airlines measure this way
Airlines use linear inches (the sum of length, width, and height) because it is a single number that tells them whether a bag will fit in the overhead bin or under the seat in front of you. A bag that is 22 × 14 × 9 inches totals 45 linear inches and fits most airline carry-on limits. A bag that is 26 × 18 × 12 inches totals 56 linear inches and will likely be checked or charged as oversized.
Different airlines set different limits. Most major carriers allow carry-on bags up to 22 × 14 × 9 inches (45 linear inches), but budget airlines like Spirit and Frontier are stricter — sometimes as low as 21 × 13 × 8 inches (42 linear inches). Checked bags usually have a limit of 62 linear inches (roughly 28 × 20 × 14 inches) before an oversized fee kicks in.
Common luggage sizes and their linear inches
| Bag Type | Typical Dimensions | Linear Inches | Best For |
|---|---|---|---|
| Personal item | 18 × 14 × 8 inches | 40 inches | Fits under seat; no overhead bin needed |
| Carry-on (standard) | 22 × 14 × 9 inches | 45 inches | Overhead bin on most airlines |
| Carry-on (oversized) | 24 × 16 × 10 inches | 50 inches | May be checked or charged on some airlines |
| Checked bag (standard) | 28 × 20 × 12 inches | 60 inches | Checked baggage on most airlines |
| Checked bag (oversized) | 30 × 22 × 14 inches | 66 inches | Oversized fee applies; check airline policy |
What to do if your bag is too large
If your bag exceeds the carry-on limit, you have three options: check it (if you are willing to pay the fee and wait at baggage claim), buy a smaller bag, or pack less. If your bag is only slightly over — say, 47 linear inches instead of 45 — some airlines will still let it through, especially if it is soft-sided and compresses easily. But do not count on it.
If your checked bag is over the standard limit (usually 62 linear inches), you will pay an oversized baggage fee, typically $50 to $100 depending on the airline. Measure before you pack to avoid a surprise charge at the airport.
Frequently Asked Questions
Do I measure the inside or outside of the bag?
Measure the outside. Airlines care about the space your bag takes up in the plane, not how much stuff fits inside. Include wheels, handles, and any pockets that stick out.
What if my bag is soft-sided and compresses?
Measure it in its normal, unpacked state. If it compresses when you pack it, that is fine — airlines usually do not re-measure at the gate unless the bag looks obviously oversized. But measure it the way you plan to carry it, not in a compressed state.
Do all airlines use the same dimension limits?
No. Most major carriers (United, American, Delta) allow 22 × 14 × 9 inches for carry-on, but budget airlines are stricter. Always check your specific airline's website before you pack, because fees for oversized bags range from $35 to $100.
Can I measure in centimetres instead of inches?
Yes. One inch equals 2.54 centimetres. If you measure in centimetres, add them up and divide by 2.54 to convert to linear inches, or look up your airline's centimetre limit (usually around 115 centimetres for carry-on).
What if the airline's website does not list dimension limits?
Call the airline directly or check their baggage policy page. Most post limits clearly, but some bury them. Having the exact number before you pack saves time and money.