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

“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.”

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.

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.