Southwest Low Fare Calendar: How It Works and the Cheapest Days to Fly in 2026

I priced Las Vegas to Chicago last month. Friday morning came back at $166. I shifted the same trip two days earlier and it fell to $79. Same airline, same route, almost the same flight time.

Finding that took about eight seconds, not thirty searches, because the Southwest Low Fare Calendar puts a whole month of prices on one screen.

Here is how the tool works, what the prices actually cover in 2026, and answers to the questions travelers ask most often.

What the Low Fare Calendar Is

It's a free feature on southwest.com and in the Southwest app. Pick a route, pick a month, and you get a grid of dates with the lowest starting fare for each day.

No account. No login. No fee.

You can switch the grid between dollars and Rapid Rewards points, and it handles one way as well as round trip.

One thing catches almost every first-time user. That number on each date is a starting-from price. It belongs to one flight, at one time, with a limited number of seats behind it. Often it's the 5:40 a.m. departure or the one connecting through Denver. Click into the date and the flight you actually want may cost $30 or $50 more.

How to Use It

On the website: 

1. Open southwest.com and go to the Flight booking section
2. Choose Low Fare Calendar
3. Enter your departure city, destination, trip type, and passenger count
4. Pick your travel month
5. Search, then read the grid

The app follows the same path. Tap Flight, tap Low Fare Calendar, enter your route and month.

That's the easy part. Reading the grid well is where the money is.

What Changed in 2026

This is where older blog posts will steer you wrong. Plenty still claim Southwest gives you two free checked bags and lets you sit wherever you like. Both of those ended.

Southwest now sells four fare bundles:

Bundle	Your seat	Checked bags
Basic	Standard seat assigned at check-in	You pay
Choice	Pick a Standard seat when you book	You pay
Choice Preferred	Pick a Preferred seat near the front	You pay
Choice Extra	Pick an Extra Legroom seat, or any seat	Two included

 

The calendar nearly always shows the Basic fare, because that's the cheapest option on the date.

Bags cost money now on Basic, Choice, and Choice Preferred. Fees have changed more than once, so check the current amount on southwest.com rather than trusting any blog post, including this one. The math matters. Two travelers checking one bag each, round trip, can add well over a hundred dollars to a fare that looked like a steal on the grid.

Seats are assigned. Open seating ended January 27, 2026. Boarding now runs in numbered groups, one through eight. On a Basic fare your seat is handed to you at check-in, which often means a middle seat toward the back. Flying with kids? That's the detail to watch.

EarlyBird Check-In is retired. A paid Priority Boarding option replaced it, bought closer to departure.

So: traveling light with a carry-on, Basic straight off the calendar is still strong value. Checking two bags, price it against Choice Extra first. Two included bags can make the pricier bundle the cheaper trip.

Reading the Grid Like a Regular

Check the months on either side. Takes seconds, and I've seen $60 to $100 swings between the last week of one month and the first week of the next.

Midweek usually wins. Tuesday and Wednesday beat Friday and Sunday on most routes. Early morning and late evening flights sit lower still. Thanksgiving and spring break break the rule completely.

Watch for schedule releases. Southwest doesn't open eleven months of inventory the way most carriers do. It publishes flights in batches, generally six to eight months out. Right after a batch opens, the cheapest fare buckets are still full and the calendar looks noticeably better than it will two weeks later.

Track your fare after booking. Southwest still charges nothing to change a flight. If the price drops, rebook and keep the difference as credit or points. No other major U.S. airline does this, and hardly anyone uses it.