Checking a bag has gotten more expensive across the board, as airlines are increasing their fees due to rising fuel costs amid the war with Iran.

In recent months, American, Alaska, Delta, JetBlue, Southwest and United have all announced price hikes of about $10 more per bag, with most checked luggage fees for domestic flights now starting at $45 for the first bag.

With summer travel approaching, travelers could feel that financial pain — but there are solutions to avoid hurting their wallets.

Paul Stewart, founder of shipping company My Baggage, told The Post that the answer isn’t a bigger carry-on bag — it’s packing smarter with the one you already have on hand.

“Most people assume they can’t fit a week’s worth of clothes in a carry-on, so they default to checking a bag without even trying,” he explained. “But the travelers who never pay baggage fees aren’t doing anything radical. They’ve just learned a handful of techniques that genuinely double the usable space in a standard cabin bag.”

Below are some tricks of the trade that Stewart has shared for tripped-up travelers.

Get rolling

To pack smarter, Stewart suggested rolling your clothes rather than folding — but you have to know what to roll.

Rolling T-shirts, jeans and casual tops can drastically increase how much one can fit in a carry-on compared to folding things flat, he told The Post. However, more structured items, such as blazers or dress shirts, should still be folded to avoid creasing.

“The sweet spot is a hybrid approach: roll your soft items and fold your structured ones,” Stewart said.

Break up the bulk

He also said that travelers should decant everything — not just liquids.

It’s common for people to pour their liquids like shampoo and body wash into travel-sized bottles, but Steward said you should stop there.

“The average traveler can save a significant amount of space just by stripping out unnecessary packaging before they even start packing clothes,” he explained.

Rather than bringing a bulky bottle of painkillers, put them into a small Ziploc bag, and transfer your vitamins and other medications into a pill organizer.

Here’s a shoe-in

One underrated hack is utilizing the dead space inside your shoes.

They often take up the most space when packing, so Stewart suggested using them as a vessel to store other items so as not to waste the space — consider stuffing them with socks, chargers or small toiletries.

Then, pack the shoes sole-to-sole along the spine of the suitcase, which will keep the shape of the bag stable and free up a “surprising amount” of room, he said.

When packing shoes, it’s also important to be strategic about what you’re bringing, advised Leslie Coleman, founder of women-focused travel company Suitcase Gals.

“Shoes are often the most overpacked item,” she told The Post, recommending that travelers stick to versatile pairs that can be used for a variety of occasions.

Maximize mix and match

Building a capsule wardrobe for a trip will help immensely as well.

Stewart suggests packing three bottoms, five tops and one versatile layer for six or more outfits, if everything can mix and match within a single color palette.

“The travelers I see doing this consistently are the ones who never need to check a bag, no matter how long the trip. It is not about packing less — it’s about packing smarter,” he shared.

Coleman echoed that sentiment, saying that mix-and-match pieces can help travelers pack lighter while still feeling prepared for any part of their trip.

“No one notices if you repeat outfits,” Coleman noted, adding that outfits should be planned according to your itinerary. “Think about the weather, how many days you’ll be traveling, whether laundry will be available, and the types of activities or events you’ll be attending.”

Don’t delay the TSA

When packing in a carry-on, it’s also important to make sure you avoid any of the common mistakes that will make your travel journey harder at TSA checkpoints.

The most common mistake is liquids, according to Chris Harrington, managing director of airport transportation site hoppa. It’s vital not to forget to decant your liquids or bring travel-sized items that adhere to the 3-1-1 rule.

“Things like shampoo, sunscreen, skincare products and even toothpaste tend to be items that get flagged the most,” Harrington told The Post. “To avoid this, either buy mini-versions or, if you want to be more cost-effective, invest in some clear, travel-sized bottles and transfer the liquids this way.”

Any liquids and electronics should be placed on the top of your bag for easy access at security as well. That way, you won’t have to dig through your now-perfectly packed bag at security — not to mention hold up the long queue of peeved travelers behind.

“If there’s a line, this can massively slow down the screening process and lead to additional security checks. Being prepared is key here,” Harrington said. “This will help avoid delays, items being flagged for further inspection, and saving yourself time in the process.”

‘Packing smart costs nothing’

Even though current baggage fee hikes were due to jet fuel shortages caused by the current geopolitical situation, Stewart said that the increases aren’t going away, and travelers should learn how to pack smarter to save money.

“If anything, airlines are finding more creative ways to charge for what used to be standard,” he said. “Packing smart costs nothing. Just learn a few simple habits and most people will never need to check a bag again, no matter how long the trip.”

Coleman added that if you are convinced you need new travel totes anyway, at least baggage manufacturers have stepped up their game — especially regarding carry-ons.

“Luggage makers have gotten so creative, designing bags that are lighter, smarter, and somehow fit everything you think you need without the bulk,” she said. “For quick getaways, it’s a total win. I love skipping the baggage claim, avoiding extra fees, and walking straight out of the airport into my adventure.”