Travelers are booking open-jaw flights to Europe to save money and extend trips. A travel advisor explains how it works.

• Travelers can save on airfare by booking open-jaw flights for European trips.
• The flights land in one city and depart from another, making it easy to visit multiple destinations.
• Open-jaw flights offer flexibility and are typically cheaper than round-trip options.

When traveling through Europe, many tourists like to maximize their trip by hitting more than one destination. It's easy to visit multiple countries in one trip thanks to the continent's massive, convenient train system.

According to Sonia Bhagwan, the owner and senior travel agent at Dreaming of Sun — Dream Vacations, vacationers can save a lot on airfare by booking open-jaw flights — a method of traveling where you fly into one city and out of another, rather than booking a round-trip flight and returning to the first destination.

"In past years, round-trip flights were the most economical," she told BI. "But in the past nine months, open-jaw flights have been less expensive and offer additional flexibility for seeing multiple destinations without being rushed."

Bhagwan told BI that she often suggests open-jaw flights for clients, especially those traveling to Europe. She said they're most popular for trips to England, Spain, and Italy.

"A solid 75% of my families traveling to Europe use this method to maximize their time and money spent," Bhagwan said. "Most times, it will save them a few thousand dollars."

How to book an open-jaw flight

When searching for an open-jaw flight, don't hit the "one-way" tab. Instead, on most search engines, you'll find an option labeled "multi-city."

BI previously reported that these flights are typically cheaper than one-way flights.

According to a Google Flights search for about six months in advance, it costs about $700 with the multi-city tool to fly from NYC to Rome and then from Barcelona back to NYC. But with the one-way tool, it's nearly $1,000. And a train from Rome to Barcelona may cost around $80, according to Rail Europe, so open-jaw flights would save $220.

Some savings can be even greater. In another search in the same timeframe, flying from Indianapolis to Paris and then from Madrid back to Indianapolis would cost about $930 with the multi-city tool and $1,600 with the one-way tool. Factor in a $65 train ticket, according to Rail Europe, and you'd save about $600.

Considering that these prices reflect just one person, it's easy to see how families can save thousands.

How to maximize money saved

According to Bhagwan, the best way to book an open-jaw flight is to start searching between four and six months in advance.

"Eyeball the flight prices for a few days to get a sense of the going rate. Then start looking at those same routes weekly," she said. "You will get a sense of when prices increase and decrease."

Bhagwan says it's usually cheapest to book on a Sunday night.

"This is when new flights get added into the rotation, and prices typically are at their lowest — but not always," she said. "If the price seems high, wait a week and search again."

Bhagwan also suggests booking flexible or refundable rates directly through the airline's website.

"This is best because that allows you to change flights if you see a price drop a few weeks later," she added.

Traveling to Europe can be expensive, but open-jaw flights can make them more affordable when visiting multiple cities.