Sub-$100 Roundtrip Flights: How to Find and Book the Cheapest Domestic Fares

Cheap flights are great — but scoring a roundtrip for under $100? That’s unbeatable.

We search for cheap flights all day, every day for our Thrifty Traveler Premium members. Lately, a clear trend has emerged: Sub-$100 roundtrip flights within the U.S. are back in a big way.

It’s a welcome win for travelers hoping to get away without blowing their budget. While these ultra-cheap fares never disappeared entirely, we’re seeing more and more of them pop up for destinations across the country this winter in particular.

Why now? Simple: Airlines need to fill seats during one of the slowest travel periods of the year.

Why Are Domestic Flights Getting Cheaper?

To save on airfare any time of year, we’ve long encouraged travelers to use every trick in the book: cashing in credit card points, burning those SkyMiles, or even skipping domestic travel altogether and looking abroad for the best deals.

But now that cheap domestic fares have returned with a vengeance, you don’t have to try nearly as hard to score a great price within the U.S. So what’s driving this trend?

A big piece of the puzzle comes down to the natural ebb and flow of travel demand throughout the year. Winter is almost always a slower season for U.S. travelers, which means January and February are typically some of the cheapest months to fly. April and May also tend to offer lower prices. Travelers tied to the academic calendar often can’t – or don’t think to – travel during these shoulder-season months, saving up instead for spring break or summer vacations.

The result? Thousands of half-empty planes crisscrossing the country. And how do you fill a half-empty plane? With a $58 roundtrip fare to Florida.

Ask my coworkers and friends to gather everyone they know for a photoshop project, and they'd pick their dogs first. But this isn’t photoshop – this is an actual fare Southwest will sell you.

And it’s not just a one-off. On the domestic routes we search every day, we’re routinely seeing the lowest fares drop into double digits. For destinations like Florida, Boston, Phoenix, Las Vegas, Chicago, and more, sub-$100 – even sub-$50 – roundtrip prices are becoming increasingly common.

Here’s where we’re seeing the lowest fares right now.

Roundtrip Flights for Under $100

You're going to notice a trend in many of these flight deals, and that trend is Southwest Airlines. Importantly, that doesn't mean you have to fly Southwest, because not every low fare on this list is a Southwest flight. But most of these routes include Southwest service because Southwest's competition always drives the best airfare sales … on any airline. 

Let's say you want to fly down to Florida this winter. When Southwest ran its most recent sale, it offered up that $57 roundtrip fare from Austin (AUS) to Fort Lauderdale (FLL) I showed you above, but Southwest also flies between many of these other cities, too. 

That dropped these fares on American Airlines flights to Miami (MIA) into the $70s, $80s, and $90s roundtrip! 

The same thing happened on the west coast for this recent flight deal we sent with service to Southern California. Southwest swooped in with some ridiculous fares to SoCal, and then Alaska Airlines and Delta had to match them to remain competitive. 

San Diego (SAN) to Phoenix (PHX) is a route Southwest dominates. In order to get travelers looking elsewhere, Alaska had to sink their rates down to just $79 roundtrip! 

We see it all the time. Southwest's hub airport in Chicago (MDW) is also a catalyst for this, bringing roundtrip flights into Chicago down into the $70s or $90s. 

Southwest's flash sale into Midway (MDW) even forced airlines like American to match prices on flights into Chicago-O'Hare (ORD). 

All over the country, Southwest's influence has led to plummeting flight prices. There are more sub-$100 fares out there than you probably think … you just have to know where to look. 

These flights from Charlotte (CLT) to Nashville (BNA) and back were less than $100

As were these longer West Coast flights between Vegas (LAS) and Seattle (SEA). 

Bottom Line

If you have $99 to spend on flights, a recent run of domestic flight deals means you might not need to scrap a winter trip after all! 

Whether it’s a quick getaway to the Sunshine State, a visit to Southern California, or any of the hundreds of other routes we’ve found for under $100 roundtrip, consider this your excuse to book the trip.