Spirit and Frontier Are Cracking Down on Luggage: Here's Why It Pays to Size Bags Before You Fly

If you're flying Spirit or Frontier this summer and have chosen to carry only a personal item (without checking a bag or paying for a carry-on beforehand) then brace yourself: If it's not the right size, you might be in for an expensive surprise.

Both Spirit and Frontier are requiring all passengers to test personal items in sizing racks at boarding to determine if it meets the appropriate dimensions. If your bag does not fit within the sizer, you will be charged an additional $99 to upgrade to a carry-on or checked bag.

And trust me -- If your personal item is even a little bit too big, you'll have to pay the $99 fee.

I recently flew Frontier from Portland to Nashville (with a layover in Denver) and Spirit from Nashville to Portland (layover in Las Vegas) and each flight I was instructed to size my bag before boarding. Though mine was the right dimensions, I witnessed numerous passengers whose luggage didn't fit and were required to pay the $99 fee.

In Las Vegas, I even saw a family of six miss their flight to Los Angeles because they argued with the airline personnel and waited too long to pay the fee. By the time they had finally come around to it, the jet bridge was drawn back, the gatehouse door closed, and they had missed their flight.

What are the dimensions for personal items?

For both Frontier and Spirit, your bag (including wheels and handles) can be no taller than 14 inches, no wider than 18 inches, and no longer than 8 inches.

This would be a small backpack or duffle bag. For example, here are some appropriately sized bags you can buy on Amazon:

• Travel duffel bag designed for Spirit Airlines ($9.99)
• Laptop backpack ($36.99)
• Travel backpack ($36.99)

If you're not flying Frontier or Spirit, check your airline's guidelines regarding dimensions for personal items, as they might be different.

How much does luggage cost?

Spirit and Frontier charge different prices for luggage. But they both levy the same fee when you upgrade a personal item at the gate: $99. For perspective, here's how much both airlines currently charge for luggage:

Spirit luggage pricing

Frontier luggage pricing

Keep in mind that both airlines offer discount programs that might reduce the cost of baggage. For instance, if you're a part of Spirit's "Saver$ Club," you'll get $1 off luggage. You won't, however, get a discount if you're required to upgrade at the ticketing counter or gate.

Credit cards that reimburse you for baggage

Both Spirit and Frontier have travel credit cards, but unfortunately neither one offers free checked bags on its rewards program. If you're interested in covering baggage fees with credit card rewards, here are a few travel cards worth considering:

• Chase Sapphire Reserve®: This card will credit you up to $300 for travel purchases, which includes luggage fees. You'll receive the $300 as a statement credit on your card's anniversary.
• Capital One Venture X Rewards Credit Card: Though it doesn't offer a statement credit, this card has a super generous welcome bonus of 75,000 miles when you spend $4,000 in the card's first three months.
• The Platinum Card® from American Express: The card offers an annual statement credit of up to $200 for airport incidental fees, which includes checked bags. (Terms apply; enrollment may be required).

In the past, you may have gotten away with questionably sized personal items (I know I have). But discount airlines like Spirit and Frontier are cracking down on luggage and will charge you $99 at the gate if your bag isn't the right size. My advice: Don't take a risk. Size your bag beforehand and save money at the gate by packing an appropriately sized personal item.