If you’ve ever flown Frontier Airlines, you probably know one thing right away – their baggage rules can feel like a trap for the unprepared. Frontier is famous for ultra-low base fares, but the catch is that almost everything beyond your seat costs extra. That includes your carry-on bag.
Here’s the kicker: unlike most airlines that let you bring a free carry-on, Frontier only includes one personal item in your ticket price. If you show up with a bag that doesn’t fit their strict size box, be ready for a fee that could cost more than your ticket.
That’s why knowing Frontier’s exact carry-on rules is so important. A little preparation can save you from stress at the gate and a big dent in your wallet. In this guide, we’ll break down the official carry-on and personal item policies, the fees you’ll face if you go over, and practical packing tips to make sure you travel smarter.
Frontier Airlines Carry-On Size & Weight Policy
When it comes to Frontier, the rules are crystal clear but very strict. Unlike most airlines, Frontier does not include a standard carry-on bag in your ticket price. Instead, you’re only allowed a personal item for free. Anything bigger is considered a carry-on, and you’ll have to pay for it.
Here are the official limits:
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Personal Item (Free):
Must fit under the seat in front of you.
Maximum size: 14 x 18 x 8 inches (35 x 46 x 20 cm).
Think small backpack, purse, or laptop bag. -
Carry-On Bag (Paid):
Must fit in the overhead bin.
Maximum size: 24 x 16 x 10 inches (61 x 41 x 25 cm), including handles and wheels.
Weight limit: 35 lbs (15.8 kg). -
Checked Bags (Paid):
While this article is focused on carry-ons, it’s worth noting that checked bags have their own limits (62 linear inches, 40 lbs).
👉 The tricky part: Frontier is known for checking bag sizes aggressively. If your “personal item” is even slightly bigger than the 14 x 18 x 8 box, they’ll make you pay for a carry-on at the gate – and that’s the most expensive place to pay for it.
Frontier Airlines Carry-On Fees
Here’s where Frontier makes most of its money – from the bags. Since the airline follows an ultra-low-cost model, the ticket price looks cheap at first, but bags (especially carry-ons) quickly add up.
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Personal Item (Free):
No charge, as long as it fits under the seat (14 x 18 x 8 inches). -
Carry-On Bag (Paid):
The price depends on when and how you pay for it:-
Adding at the time of booking: $39–$57 (varies by route).
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Adding later (like through “Manage Booking”): $49–$63.
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Paying at the airport: $79.
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Paying at the gate (ouch!): $99.
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Checked Bag (Paid):
Typically cheaper than carry-ons if paid at booking. Usually starts around $34–$55 and goes up if added later.
💡 Pro Tip: Always pay for your bag when booking your ticket. Waiting until you’re at the airport – or worse, at the gate – means you’ll pay almost double.
Personal Item Rules
Frontier includes one personal item with every ticket. It must fit under the seat in front of you and it must not exceed 14 x 18 x 8 inches including handles, wheels, and straps. Typical examples are a small backpack, purse, briefcase, or laptop bag. Gate agents check this carefully, so measure at home and avoid overstuffing that makes the bag bulge beyond the box.
What counts as a personal item
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Small backpack that fits fully under the seat
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Purse or tote
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Slim briefcase or laptop bag
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Diaper bag when traveling with an infant
Quick tip
Keep medications, documents, and electronics in the personal item in case your larger bag is gate checked for a full flight.
Special Items and Exceptions
Frontier makes a few important exceptions that can save you money and stress.
Infant and child items
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Strollers and car seats are checked free of charge. You can use the stroller in the airport and gate check it. These do not count toward your baggage allowance. A diaper bag for a traveling infant is also exempt from fees.
Medical devices
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Bags that contain only medical devices and supplies are exempt from carry on and checked bag fees. Devices like CPAP and portable oxygen concentrators are allowed, but they must stay within carry on dimensions and follow usage rules. Label the device bag and do not mix non medical items inside it.
Assistive devices
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Mobility aids and the batteries that power them are exempt from charges. Follow airline instructions for handling and battery safety.
Personal Item Bags That Fit 14 x 18 x 8
Direct Amazon links only, as requested. Each of these is designed to meet Frontier’s under seat size.
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WANDF Travel Backpack 18 x 14 x 8
Lightweight, many pockets, slips over suitcase handle. -
ECOHUB Travel Backpack 18 x 14 x 8
Water resistant, organized layout, comfortable straps. -
Labitree 18 x 14 x 8 Foldable Personal Item Duffel
Packs flat, opens large, sized for Frontier and Spirit. -
Bago Personal Item Travel Duffel 17 x 14 x 7
A touch slimmer for easier under seat fit, very light. -
18 x 14 x 8 Hardside Personal Item Suitcase
Under seat mini roller with removable wheels and TSA lock. -
Frontier Sized Underseat Shoulder Bag 17.3 x 13.8 x 7.9
Soft sided and sized for the sizer with room to spare.
Frontier vs. Competitors
Airline | What is free | Carry on included | What to watch |
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Frontier | One personal item up to 14 x 18 x 8 under seat | No, you pay for overhead carry on | Strict checks at gate, buy bags early to save. (Frontier Airlines) |
Spirit | One personal item under seat | No, overhead carry on is paid | Similar strictness to Frontier. |
Southwest | Personal item and carry on are free | Yes | Two checked bags are free which is unique among US majors. |
American, Delta, United | Personal item free | Yes on standard fares | Basic Economy rules can vary, always check fare details. |
Frontier’s Strictness & Enforcement
Frontier is known for being one of the strictest airlines when it comes to carry-on and personal items. If you’ve flown them before, you probably noticed the bright green bag sizers placed at nearly every gate. And unlike some airlines that let borderline bags slide, Frontier agents often check — and if your bag doesn’t fit, you’ll be charged the steep gate fee.
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Bag Sizers: You’ll find them at check-in, security, and the gate. If your bag looks bulky, expect to be asked to prove it fits.
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Overstuffing = Risky: Even if your personal item technically fits the size limits, if it looks too stuffed, they may still make you test it.
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Carry-On Checks at Gate: This is the biggest trap for unprepared travelers. If your bag doesn’t pass, the fee can jump as high as $99.
💡 Traveler Insight: Many passengers on forums say they’ve seen dozens of people caught off guard at the gate, forced to pay the high last-minute fees. If you’re flying Frontier, it’s best to play by the rules and measure your bag before heading to the airport.
Tips to Avoid Extra Fees on Frontier
Flying Frontier can be cheap, but only if you dodge the sneaky bag fees. Here are some smart ways to keep costs low and avoid surprise charges:
1. Measure Before You Go
Frontier is strict, so don’t eyeball it. Measure your personal item (14 x 18 x 8 inches) and make sure it fits. Even a small bulge can get flagged.
2. Invest in a True Personal Item Bag
Many brands now sell “Frontier-approved personal item bags” designed to fit exactly in their sizers. Buying one of these once can save you hundreds in fees if you fly them often.
3. Pay for Carry-On or Checked Bag Early
If you need extra space, buy it during booking. Waiting until the airport or gate can double or even triple the price.
4. Don’t Overpack
It’s tempting to squeeze in just a little more, but Frontier agents are trained to spot overstuffed bags. A cleaner fit = less risk of being stopped.
5. Use Frontier’s Discount Den (if you fly often)
Sometimes, Discount Den members get lower bag fees compared to regular pricing. Worth it if you’re a frequent Frontier flyer.
6. Layer Up
If you’re stuck with a heavy personal item, wear your heaviest jacket and shoes. It saves space and weight in your bag.
💡 Pro Tip: Always assume you’ll be asked to test your bag. If you’re not confident it will fit without a fight, it’s better to pay early than to gamble at the gate.
Frontier’s Strictness Scale Compared to Other Airlines
When it comes to carry-on enforcement, not all airlines are created equal. Some turn a blind eye as long as your bag looks reasonable, while others (like Frontier) keep a laser focus on every inch. Here’s how Frontier stacks up against other major US carriers:
Frontier Airlines – Very Strict
Frontier is notorious for being one of the most unforgiving. Agents almost always ask questionable bags to go in the sizer, and if it doesn’t fit, you’ll be charged a hefty fee right on the spot.
Spirit Airlines – Equally Strict
Spirit operates almost identically to Frontier, with tight personal item rules and aggressive fee enforcement. Both are ultra-low-cost carriers, and their profits come heavily from baggage fees.
American, Delta, United – Moderately Strict
The big three (American, Delta, United) are generally more relaxed. As long as your personal item looks like it belongs under the seat, you’ll usually pass without inspection. Carry-on bags are included in standard fares, which reduces their incentive to nickel-and-dime.
Southwest Airlines – The Most Lenient
Southwest allows two free checked bags and a carry-on plus personal item. They’re hands down the most generous US airline when it comes to luggage.
💡 Bottom line: Frontier sits at the top of the strictness scale alongside Spirit. If you’re flying them, assume every bag will be checked and every extra inch could cost you.
Real Traveler Experiences with Frontier’s Carry-On Rules
One of the best ways to get a feel for how strict Frontier really is comes from people who’ve already been through it. Traveler stories show just how consistently Frontier enforces its rules:
The Surprise Fee at the Gate
Many passengers report being stopped at boarding when they thought their bag was fine. A common complaint is being forced to pay $60–$99 right there at the gate for a bag that didn’t fit Frontier’s personal item dimensions. It’s a stressful moment and often leaves people feeling tricked.
The “Soft Bag vs Hard Bag” Debate
Some travelers say they’ve been able to sneak through with a soft-sided backpack that bulges a little, while others with rigid bags of the same size were forced to pay. The flexibility of your bag can make a big difference.
Consistency Varies by Airport
Reviews show that strictness can depend on where you’re flying from. Smaller airports sometimes appear a bit more lenient, while big-city airports like Denver or Las Vegas (Frontier hubs) are often much stricter.
Positive Experiences Exist Too
Not everyone has horror stories. Some passengers who stayed well within the size rules said they had zero issues and appreciated the cheap base fares. They view it as a “pay less, follow the rules” system that works fine if you’re careful.
💬 Overall takeaway: Frontier’s carry-on policy is enforced so often that you shouldn’t expect to get away with bending the rules. If your bag even looks questionable, plan on paying the fee.
Conclusion
Frontier can be a great value when you understand the rules and prepare for them. Travel with a true under seat personal item, measure and weigh at home, and buy any extra bag allowance during booking. If you are traveling with an infant or medical equipment, use the fee exemptions that Frontier publishes so you do not pay for items that are meant to be free. With the right bag and a little planning, you can fly Frontier for a very low total cost and skip the stress at the gate.

Horace Dupuy is a seasoned traveler and luggage reviewer who has spent years flying with both major and regional airlines across the United States and abroad. His first-hand travel experience has taught him exactly what works (and what doesn’t) when it comes to carry-on rules, baggage fees, and packing strategies.
At CarryOnSizes.com, Horace combines personal travel knowledge with in-depth research to provide accurate, up-to-date guides for travelers who want to fly stress-free. When he is not writing about luggage, you will probably find him exploring new destinations with only a compact backpack in tow.