Book fast! Frontier is having a promo code sale valid for purchase through today. Save 90% off the base fare for travel through May 16. Fares start at just $37 round-trip.

Use promo code SAVE90 when booking on to take 90% off the base fare for nonstop domestic flights. Travel is valid on Tuesdays and Wednesdays through May 16.

The discount does not apply to taxes nor Frontier's online booking fee, which they label a "Carrier Interface Charge". This means some routes still won't have a very big price drop even with the big sticker shock of 90% off. However, there are plenty of routes where we are seeing very large discounts so you may be able to save big if you can travel in the middle of the week.

There is a long list of specific routes excluded from the promo code sale. Frontier operates about half of their markets on limited days each week. Click on the fare details for more info.

Tickets must be booked by 11:59pm ET, on April 10.

A sample of nonstop fares include:

Detroit to Long Island-Islip $37 round-trip

Minneapolis to Long Island-Islip $37 round-trip

Salt Lake City to Las Vegas $50 round-trip

Cincinnati to Raleigh $50 round-trip

Philadelphia to Charleston $51 round-trip

Madison to Philadelphia $51 round-trip

Denver to Boise $63 round-trip

New York to Cincinnati $68 round-trip

Charlotte to Austin $68 round-trip

Seattle to Colorado Springs $69 round-trip

St. Louis to Orlando $70 round-trip

Cleveland to Portland, OR $70 round-trip

Trenton to Nashville $70 round-trip

Raleigh to Las Vegas $72 round-trip

Las Vegas to Tampa $72 round-trip

Providence to Denver $74 round-trip

Philadelphia to Kansas City $75 round-trip

Atlanta to San Jose, CA $75 round-trip

Philadelphia to Miami $76 round-trip

Los Angeles to Atlanta $76 round-trip

Washington D.C. to Las Vegas $78 round-trip

Austin to Washington D.C. $84 round-trip

Atlanta to San Juan $98 round-trip

Many more routes are available and these fares all work in reverse as well. Lowest fares may not be available throughout the entire travel period. Check our pages for all flights to DenverLas Vegas, OrlandoTampaPhiladelphia, Cleveland, Austin, Raleigh, and San Jose to see more of today's finds. This is not a full list of Frontier cities, so check flights from your city to see what's available.

Keep in mind that Frontier charges extra for any bags larger than a small personal item (small backpack, large purse, etc.). Pack super light to get the lowest price. Checked bag fees start at $25 each way. Larger carry-on bag fees start at $30 each way.

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