6 Best Websites for Booking Cheap Flights

The desire to get a good deal unites practically all travelers. Whether you're looking for a cheap getaway or a luxury vacation, no one wants to spend more than necessary. When it comes to booking flights, travelers may naturally head to an airline's website. However, that's not always the best site to book flights.

Whether it's taking advantage of credit card perks, earning bonus miles or saving money, the best flight booking site can vary depending on your situation and willingness to get creative. Let's take a look at six of the best sites to book flights and when each is the best option.

» Learn more: The best travel credit cards right now

The best flight booking sites

1. Google Flights

For ease, speed and features, Google Flights is arguably the best website for flight searches. Search results appear almost instantly. Filters let you narrow down to nonstop options, select a subset of airlines, limit by price or factor in the price of a bag. Similarly, you can use Google Flights filters to avoid certain airlines, multi-stop itineraries, long layovers, early flights or pretty much whatever you might want to avoid.

You can easily check flexible dates, and if you're flexible on where you go you can use the Explore map to see prices for a variety of destinations for certain dates, a certain month or anytime in the next six months.

Google Flights partners with hundreds of airlines and online travel agencies (OTAs) to pull current flight prices. That way you don't have to search each of these sites to be able to see the options. Once you select your preferred trip, Google Flights links you to the top booking options for actually booking your flight — including the airline itself and the best OTA booking options.

The downsides of Google Flights are few. One is the lack of Southwest flight prices. Although Southwest flight schedules will show in flight search results, Southwest flight prices aren't available. That's because Southwest chooses to publish flight prices only on its website.

» Learn more: Why Southwest is not on Google Flights

Another downside is that Google Flights doesn't always show the cheapest prices — particularly for international flights. That means it's worth double-checking prices on another site before booking through Google Flights.

2. Kayak

Like Google Flights, Kayak searches hundreds of other websites and flight booking platforms to find the best deal. Kayak generally doesn't let you book flights directly. However, one benefit of Kayak is the streamlined process. Rather than having to click through several pages to confirm your selection, clicking "view deal" on the results page can take you right to the cheapest booking option.

Also, some travelers may find Kayak's flexible date search a bit easier to work with as you can see results from several days in the search results — eliminating the need to check each day's results separately.

But perhaps the most important reason to use Kayak instead of Google Flights is that it can catch better deals. For example, we found a $550 round-trip flight from Los Angeles to Barcelona using Google Flights. Kayak found a way to lower that price to just $472 round-trip — at least once you scroll past an advertisement.

Note that Kayak manages other flight search sites — including Momondo and Cheapflights — so the results may be very similar between these sister sites.

» Learn more: Is Kayak legit?

3. Expedia

So far, we've focused on ease in flight searching, and that's going to be enough for many travelers. However, now let's add in some additional elements to consider when choosing the best flight booking site: earning rewards and saving by booking packages. Expedia excels at both of these.

Through the new One Key rewards program, travelers can earn 0.2% in OneKeyCash from flight bookings made through Expedia. That's not much, but it can stack on top of the awards you earn from the airline and those that you earn on your credit card purchase.

Even better, you'll earn credits toward One Key elite status by booking your flight through Expedia. As you climb up the tiers, you'll unlock up to 20% savings on hotels, get hotel upgrades, priority support and even price drop protection.

Plus, Expedia boasts that travelers can "save up to 30%" when bundling a hotel with a flight booking — although actual discounts are likely to vary.

» Learn more: The pros and cons of Expedia

4. Capital One Travel

For many Capital One cardholders, Capital One Travel might just be the best flight booking site. Part of this is to take advantage of cardholder benefits.

For example, Capital One Venture X Rewards Credit Card holders earn 5x Capital One miles when booking flights through the Capital One Travel portal. Plus, Capital One Venture X Rewards Credit Card holders get up to $300 off travel booked through the Capital One Travel portal each cardholder year.

» Learn more: How to maximize the Capital One Venture X Rewards Credit Card

Also, Capital One Travel can help you truly get the best price for your flight. Capital One partnered with travel data company Hopper to show suggestions about when it's the best time to book.

Capital One backs up these recommendations with money. If you book a flight through Capital One Travel when Hopper recommends doing so, you'll get up to a $50 credit toward future travel if the price drops within the next 10 days.

» Learn more: How the Capital One Travel portal works

5. Kiwi

Would you be willing to book a trip as two separate tickets in order to save money? That's the idea behind Kiwi. Instead of simply searching flights from your home airport to your destination, Kiwi checks all potential options to get between A and B. That could mean taking a bus or train from your home city to another to catch a flight to your destination. Or, Kiwi might pair a low-cost domestic flight with a cheap international flight from another city to lower your total cost.

For example, when we priced out a round-trip flight from Phoenix to Tokyo, the cheapest option when booked as one ticket cost $1,353 round-trip — and that's with an overnight stay in Vancouver.

Pricing out the same itinerary and dates through Kiwi drops the price to just $789 round-trip. The secret? Booking this as two round-trip flights: One from Phoenix to Los Angeles on Frontier and a separate round-trip from Los Angeles to Tokyo on Zipair.

Keep in mind that there are risks with booking separate tickets to get where you want to go. If a delay or cancellation causes you to miss your connection, the second airline/bus/train company isn't obligated to honor your ticket and rebook you on the next option. So make sure to factor in all of the risks of booking travel like this.

» Learn more: When to use Kiwi for your next flight booking

6. BookWithMatrix

ITA Matrix is a very powerful and ultra-customizable search platform for finding exactly the flight itinerary you want — whether that's booking a longer layover, avoiding certain aircraft types or booking nerdy trips such as the Alaska Milk Run.

The catch: Travelers can't actually book flights through ITA Matrix. And, unlike Google Flights, ITA Matrix doesn't even link to the best flight booking site for that itinerary. Instead, travelers are left to attempt to re-create the same itinerary through another flight booking website — which can be hard in the case of certain complex itineraries.

Enter BookWithMatrix. Travelers can copy-paste their perfect itinerary from ITA Matrix into BookWithMatrix to get bookable links through the airline or select OTAs.

Alternatively, travelers have the option to install the PowerTools extension in Google Chrome.

This extension adds booking links right on the ITA Matrix itinerary page, avoiding the need to browse to another page.

Final thoughts on the best flight booking site

There's not a one-size-fits-all best website for booking flights. Instead, the best flight booking site for you is going to depend on how simple you want the process to be, whether you're willing to get creative with your booking, and even which credit cards you have.

For most travelers, the simplicity of Google Flights is going to make it the best one-stop shop for searching and booking flights. However, it's worth considering other options if you're flying internationally, want to book a flight-and-hotel package or have a Capital One Venture X Rewards Credit Card.