Looking for the Best Deal on Airfares? Consider a Price Freeze.

To buy or to wait? Given the wild fluctuations of airfare prices, that is a frugal flier’s persistent dilemma. A fare found today may tick up tomorrow, double next week or fall.

Now Google and other online travel platforms aim to take the uncertainty out of the equation by offering guarantees or freezes, often on fares they predict won’t shrink.

Sitting on mountains of data, these platforms say they have a good grasp on predicting price fluctuations. On fares where guarantees are offered, “our algorithms are confident that the price is unlikely to drop between booking and departure,” said Jade Kessler, a product manager for Google Flights, which recently launched its Price Guarantee pilot program. “Our goal really is to help travelers avoid that feeling of buyer’s remorse and help them to know that no matter what happens after they book, they’re getting the best deal possible.”

Like Google Flights, Kayak already allows travel shoppers to track flights for insights on pricing trends and recommendations on when to book. Though not necessarily available on every flight, guarantee and price-hold programs go a step further, and often cover hotel and car rental reservations, too.

But how do they work, and are they worthwhile? To find out, we analyzed the leading programs in price freezes and guarantees that don’t require a membership to access.

Google Flights

This month, Google Flights announced a pilot Price Guarantee program that will monitor an eligible flight from purchase to take off and refund the difference between the airfare paid and the lowest fare found in that period, as long as it is more than $5.

How it works: Travelers must book their tickets on Google Flights, which, unlike online travel agencies, acts like a pass-through sales portal so that fliers can still accrue loyalty points and hear directly from an airline about schedule changes. Eligible flights must originate in the United States. To date, there are relatively few that qualify. The platform is primarily working with Alaska, Hawaiian and Spirit.

Searching popular routes on those airlines on Google Flights, I recently found a $144 round-trip in May between Chicago and Las Vegas operated by Spirit that had the Price Guarantee badge. I had the option to Book on Google to get the Price Guarantee at the same price as booking on Spirit. Google’s price analysis showed the fare was $90 cheaper than usual, so I did not expect it to fall.

Google Flights then monitors the price fluctuations of that ticket between purchase and takeoff and sends a status update at the halfway date. If a fare has dropped at any point after purchase, Google will refund the difference if it is more than $5. Since fliers must take the trip to qualify for a refund, Google Flights deposits any refund to a Google pay account. Those who use Price Guarantee must have a Google Pay account, and the company provides instructions for setting one up.

Cost: Participation is free. User refunds are capped at $500 annually.

Bottom line: Google Flights’ Price Guarantee goes a long way to providing assurance that travelers can buy with confidence. Its chief problem is its limited availability, which the company says it hopes to expand after the trial phase is over, though it didn’t specify a date.

Hopper

The travel booking app Hopper offers a Price Freeze feature that allows users to lock in an airfare for a fee and book later. If the price goes up before booking, the consumer pays the lower frozen price; if it goes down, the consumer pays the lower price. Hopper offers a similar program with hotel and car rental reservations.

How it works: Travelers searching for flights can choose to hold a price for a fee and a set period. Fees depend on the ticket price and the hold length; the company said the average freeze costs $47 and that most users freeze a fare for seven days. Within that window, if a fare rises, Hopper pays the difference up to a cap of $300 a ticket. If it falls, users pay the lower fare and forfeit the fee.

You don’t have to pay anything to get Hopper’s insights into pricing. Hopper already analyzes airfares during searches, indicating whether you should “wait for a better price” or “book now.” In a recent search for a flight from Newark to Miami in late May, I found a $76 round-trip ticket with the advice to wait for a lower fare. It also offered the option to pay $12 to freeze the fare and wait one day, $13 for three days, $21 for a week or $27 for two weeks. If the price went up on a frozen fare within the hold period, Hopper would pay the difference. If the price goes down, the user would pay the lower fare.

Price freezes on hotels and cars work similarly, though in the case of hotels the fee is applied as a deposit on the booking.

Cost: Freeze fees, which are nonrefundable, vary by length and reservation price.

Bottom line: Hopper provides advice on whether to book flights based on its analysis of more than 65 trillion data points and says it’s able to predict future prices with 95 percent accuracy. (It says it saves users an average of $65 a trip.) Price Freeze on flights provides assurance for those who don’t want to gamble, though the fees can be budget-busters.

Many hotels and car rental companies offer generous cancellation policies, so check those companies for direct bookings before freezing a price, since Hopper’s fees are nonrefundable.

Expedia

On its app, the online travel agency Expedia offers Price Drop Protection on most flights. For a nonrefundable fee, the service will monitor the price of a flight booked through Expedia. If the price drops, the service will refund the difference.

How it works: Using the Expedia app, a flight search turns up a price-tracking screen with insights into past price fluctuations and future predictions — insights it began offering last year — along with current fares and the option to hedge against them falling. On a recent search, the lowest round-trip in late May between New York and Los Angeles came up at $219, which Expedia predicted would be the “best price we expect to see between now and takeoff.” Nevertheless, it offered Price Drop Protection at $21, meaning that if the fare fell between purchase and take off, Expedia would refund me the difference.

Cost: Fees, which are nonrefundable, vary based on the ticket price, but there’s no annual limit on refunds.

Bottom line: Expedia’s price insights offer a guide on whether buying Price Drop Protection might be worth it. In the previous example, I would be betting $21 that my fare would drop more than $21, or to below $198, which seemed unlikely.

Airline price holds

When searching for flights on the websites of a few major carriers, including American and United Airlines, consumers can opt to freeze a fare for a while.

How it works: United’s FairLock program allows users to hold a fare for a fee, which varies based on ticket price and length of the hold. Using a recent search for a round trip in May between Chicago and San Francisco, a $372 fare would cost $5.99 to hold for three days, $8.99 for a week and $12.99 for two weeks. Within the hold period, users can pay the guaranteed price for the flight or let it expire. Either way, the fee is nonrefundable.

American Airlines says it offers free 24-hour holds and extended hold options with nonrefundable fees on select flights. A recent search for a round-trip flight in May from Dallas-Fort Worth to Los Angeles turned up a $366 round-trip fare. After clicking through to the final payment page, I was offered a 24-hour complimentary hold. Despite numerous other searches, I was unable to find an extended hold offer.

Cost: When applied, fees are nonrefundable and vary with the ticket price and hold term.

Bottom line: Regardless of hold offers, all carriers are required to refund any airline reservation canceled within 24 hours of purchase. So, if it’s just a matter of syncing schedules with fellow travelers or getting a quick approval at work, you’re better off buying a United fare knowing that it is fully refundable up to 24 hours rather than paying for the hold. American’s free 24-hour hold offers a grace period without the hassle of having to cancel a new reservation and request a refund.

If you need more than 24 hours to decide, a price hold might be worth it. Look for advice from Kayak, Google Flights or Expedia on whether to book or wait.

Booking.com

Through its We Price Match guarantee, the online reservation service will meet a lower price on a hotel room found on another booking site.

How it works: When users who have made a hotel reservation at Booking.com find a cheaper price for the same hotel and accommodation type with the same terms — including check-in and checkout dates and cancellation policy — at least 24 hours before their stay, they can request a refund by filing a claim on the website.

In this case, the onus is on the user to search for lower prices. There are exceptions that exclude cheaper prices found, including those that use a discount code or are generated by a hotel loyalty membership.

Cost: Free.

Bottom line: Many hotel companies, including Marriott and online agencies like Orbitz, offer price guarantees for lower rates found elsewhere within 24 hours of booking. Booking.com extends that assurance for the entire pre-travel term, though consumers will have to do their own digging to find cheaper rates.

AutoSlash

AutoSlash monitors existing car rental reservations, letting users know when the price for a rental drops, allowing them to cancel the old reservation and to rebook at the lower rate.

How it works: AutoSlash takes advantage of the generous cancellation policies of car rental companies, which generally don’t charge a penalty if you cancel a booking (excluding nonrefundable prepaid bookings). Travelers holding reservations can engage the online platform AutoSlash by providing their confirmation number, price quote and any memberships they might have to organizations like AAA or AARP or retail clubs like Costco that can trigger discounts. The service then tracks the booking and will notify users when the price drops. If it does, AutoSlash will notify the reservation holder who can cancel and rebook at the lower prevailing rate.

Cost: Free.

Bottom line: AutoSlash does the price-tracking legwork, but you’ll have to act quickly on its advice to cancel and rebook, lest the rates change again.