United celebrates 'Pi Day' with one-way flights for $31.40 or 3,140 miles

We could all use something to celebrate — this weekend, "Pi Day" will have to do. This particular event acknowledges the alignment of today's date, March 14 (3/14), with the mathematical constant pi, roughly equivalent to 3.14159. (Unfortunately pi only dates back to the 18th century, but I'd otherwise agree that there was a huge missed opportunity in the year 159.)

Anyway, let's talk travel, and save the math for calculating the number of miles you'll save with United's latest themed sale!

To mark the occasion, United is selling one-way flights for $31.40 or 3,140 miles. Note that most of the discounted paid flights will book into basic economy, and exclude seat assignments, carry-on bags and more. While we value United miles above the 1-cent valuation United's attached here, you'll have much more flexibility — and added benefits — by booking this sale as an award.

The lowest fares are typically only available on shorter United flights, though the carrier is also offering discounts on certain longer flights, so it's definitely worth looking around. Depending on the route, you'll likely encounter one of the following fare-redemption pairings:

Airline: United
Routes: between DEN/EWR/IAD/IAH/LAX/ORD/SFO and more
Cost: $31.40 or 3,140 miles one-way
Dates: Valid for travel from March 28, 2021, to June 5, 2021
Pay With: The Platinum Card® from American Express (5x on airfare booked directly with the airline or through American Express Travel ; earn 5x points on up to $500,000 on these purchases per calendar year), Citi Prestige® Card (5x on airfare), Citi Premier® Card, Chase Sapphire Reserve (3x on airfare), American Express® Gold Card (3x on airfare when booked directly with the airline) or Chase Sapphire Preferred Card (2x on travel)

The information for the Citi Prestige Card has been collected independently by The Points Guy. The card details on this page have not been reviewed or provided by the card issuer.

I found it easiest to search on Google Flights. From there, once you zero in on a "$32" fare, you can head over to United's website to book.

Once you click through, you'll see that the final price drops to $31.40, as long as you've selected an eligible flight.

There actually appears to be more availability for discounted awards, which may price out at the reduced rate every day of the week.

Once you click through to check out, you'll see the 3,140-mile rate reflected, plus the TSA security fee of $5.60 each way.

There are discounted flights available from all of United's hubs, with significantly lower fares on certain routes.

Day-of-departure restrictions may apply — on some routes, you might only see mid-week flights priced at the "Pi Day" rate.

There are many more options available at slightly higher price points, too, like Houston (IAH) to Los Angeles (LAX) for $49 in basic economy (or just $10 more for regular coach).

The award equivalent actually prices out a bit lower than advertised, at 5,000 miles each way.

Maximize your purchase

Don’t forget to use a card that earns additional points on airfare purchases, such as The Platinum Card® from American Express (5x on flights booked directly with airlines or American Express Travel), Chase Sapphire Reserve, Citi Premier® Card (3x on airfare), American Express® Gold Card (3x on airfare booked direct or via Amextravel.com), Citi Prestige Card (5x on airfare) or the Chase Sapphire Preferred Card (2x on all travel purchases). Check out this guide for more on maximizing airfare purchases.