Paris, France
Credit: Getty Images

Summer is the time for grand travel plans.

Whether you’re determined to jet across the ocean on a Euro-trip, check off multiple destinations on an Asian excursion or trek your way through South America, this is the season to embark on your big trip. But that big trip can cost a bit less if you know how to book it.

United Airlines has a little-known perk that allows travelers to receive one leg of a multi-leg journey for free when they book with miles or points.

The United Excursionist Perk works on multi-leg journeys with at least three legs. One way to think of this is extending your trip via a “stopover” of sorts.

One example that United uses is a European jaunt from Chicago. If a traveler wanted to book a journey from Chicago to London, London to Paris and then Paris back to Chicago, they could nab the London to Paris leg of the journey for free.

But the Excursionist Perk also works for more complicated itineraries. You could go from Mexico City to New York to Las Vegas to San Diego back to Mexico City and book the New York to Las Vegas or Vegas to San Diego routes for free. The formula is widely applicable to any journey in any part of the world.

All that matters is that the journey must start and end in the same MileagePlus defined region. (Mainland U.S., Alaska and Canada is one, Europe is another, among many.) The free leg of the trip must be outside of the start/end region but that leg should take place within a single MileagePlus region.

In order to take advantage of the Excursionist Perk, you need to use the Advanced search tool when booking a ticket through United’s website. Select the multi-city option and then input your destinations. If your itinerary falls within United’s rules, one of the legs should appear costing 0 miles.