12 popular myths about buying plane tickets to stop believing if you want to save money

• Plane tickets aren't always cheapest on Tuesdays and booking early won't always save you more money.
• Layovers can save you money and some non-refundable tickets can be refunded.
• You may want to buy tickets online while in incognito mode to save more money.

From regional pricing to flight search engines, there are many variables that determine how much you pay for air travel.

Here are 12 misconceptions about plane tickets, plus how you can save money when booking your next trip:

MYTH: Tuesday is the cheapest day of the week to purchase tickets

Tuesday isn't always the cheapest day to buy plane tickets, but prices can be more affordable on certain weekdays.

According to a 2017 report by Bloomberg that analyzed data from the airfare-forecasting company Hopper, the Tuesday rule only applies to 1.6% of domestic US flights, and only if you book right at midnight. Even if you complete the sale at 12 on the dot, you're going to save just $18 on average.

Larger discounts do exist, but they're more common for international flights. Nine hundred of the 3,500 global routes Hopper examined offered an average discount of $20 per ticket on Thursdays, and 600 shaved off $30 on Mondays.

Thursdays are also a good bet for cheaper domestic flights. Hopper found that, on average, 3,500 out of 7,500 domestic routes lowered prices by $12 that day. On Wednesdays, 3,000 US routes offered a similar discount.

Plus the 2019 CheapAir.com Annual Airfare Study, which looked at 917 million airfares across over 8,000 markets and found that the day of the week you purchase your tickets "has a negligible effect on flight cost" with rates varying by about $1 within a week.

MYTH: The earlier you book tickets, the more money you'll save

The same study from CheapAir.com noted if you book between 203 and 315 days in advance, you'll have the most options for airlines and seats - but you'll pay an average of $50 more per ticket.

According to CheapAir, the prime booking window (the time frame during which you'll save the most) is 21 to 115 days before your departure.

MYTH: Some destinations are always pricey

In 2018, using data from the flight search-engine Hipmunk, GoBankingRates determined the cheapest destination to visit every month of the year.

If you time your trip right - and are open to smaller cities like Lille, France, and Comporta, Portugal - the savings can be worthwhile. For instance, if you plan to go in May, you may be able to fly to Sao Paulo for as little as $750, instead of $2,000 or more.

MYTH: You have to book all legs of a long-haul trip through the same airline

If you book multiple legs of an international trip separately and are open to budget airlines such as Wow Air and Norwegian, long-haul flights can be more wallet-friendly.

According to the budget travel blog Thrifty Nomads, Kiwi.com (which also calculates affordable train and bus options) is one of the best resources for mixing and matching long-haul routes.

Likewise, booking separately can save you money on domestic flights.

MYTH: If you and your friends are booking seats on the same flight, you should purchase your tickets in one transaction

In other scenarios, like when a grocery store is running a two-for-one sale, buying in bulk will save you money. But airlines sometimes charge more per ticket if you book seats for multiple passengers.

Due to booking algorithms, there can be up to 10 different prices for the same seat on a domestic flight.

To avoid paying more than necessary for multiple tickets, Consumer Reports recommended splitting your ticket purchase among members of your party or finding airlines that take group reservations, which works for parties of 10 or more people.

MYTH: Layovers are a nuisance ― and should be avoided at all costs

Flights with layovers are known to be cheaper than direct routes. Layovers also offer another benefit called "hidden city ticketing."

In a 2018 interview with Insider, Scott Keyes, CEO and cofounder of Scott's Cheap Flights, explained the concept with the following example: If you want to travel between two major cities, such as Chicago and New York, you could book a flight from Chicago to Burlington, Vermont, that stops in New York, and skip the connecting flight.

Although the practice is legal, there are a few caveats to keep in mind.

"It is 100% legal, but it is against the airline's contract of carriage, meaning that they don't like it when passengers do this," Keyes said. "If the airline knows that you are doing it, then they might not let you on that plane, or they can kick you off."

If you want to take your chances with hidden city ticketing, he advises not purchasing a round-trip ticket and only bringing carry-on luggage.

MYTH: Your browsing history doesn't matter when it comes to buying tickets

Thanks to dynamic pricing, ticket prices can increase just by repeatedly searching for certain routes. To avoid fare hikes, clear your browser's cookies or search in an incognito tab.

MYTH: You always have to pay for an upgrade

To improve your chances of a free upgrade, you can try buying a full-fare economy ticket with a Y or B booking code.

If there are available spots in the next service class, you'll receive a complimentary upgrade, Amy Lee of TravelNerd.com told Insider in 2013.

This trick is the most effective if you're a frequent flyer and are loyal to a particular carrier.

MYTH: All flight search engines are created equal

If you look up the same route on various flight search engines, don't be surprised if the prices vary.

To illustrate that not all airfare search sites are created equal, Frommer's compared and contrasted 10 booking engines and aggregators, including Priceline and Kayak, based on last-minute and advance-purchase fares for major gateways (NYC to LAX), secondary gateways (Philadelphia to Rome), and less-common routes (Denver to New Delhi). The travel-guidebook company learned that only some search engines identified the cheapest routes.

Overall, each site had its own pros and cons, so it's worth experimenting with search engines until you find one you like.

MYTH: Regional pricing doesn't exist

Flight prices can vary depending on your location, especially for international flights. Thankfully, there are a few ways to get around this hitch.

You can either fake your computer's IP address by using a virtual private network or purchase tickets from the airline's foreign site in the local currency. For instance, if you're flying to India from somewhere in the United States, you can book your tickets through www.airindia.in instead of www.airindia.com.

If you opt for the local currency solution, make sure to purchase the tickets with a card that doesn't impose a foreign transaction fee.

MYTH: Non-refundable tickets are never refundable

Flight change fees are notoriously expensive, but there's actually a change/cancellation window built into all non-refundable tickets that's regulated by the US Department of Transportation.

If you've booked your ticket seven or more days before your scheduled departure, the DOT mandates a free change or cancellation within a 24-hour period.

The only catch is that airlines are not required to offer both options. This also only applies to a flight going to or from the US.

MYTH: Frequent-flyer miles aren't that useful

You might think airline rewards programs are just a gimmick, but they're quite useful if you do your research.

Some programs allow travelers to earn and redeem rewards by booking through other airlines within the same alliance network or partnership, such as the Star Alliance (members include United, Lufthansa, and Singapore Airlines, among other major carriers).