Want to make sure the seat next to you on your next flight is open?

The only way to do that on U.S. airlines is to buy that adjacent seat at full price.

But overseas, a number of airlines will block the seat next to you — or an entire row — for a nominal upgrade fee.

In Australia, Qantas now offers a neighbor free seating option — the fee varies by route but it’s only about $30 to $60.

Air New Zealand has a similar program.

Emirates allows travelers to buy up to three adjoining seats — but only at the airport counter right before departure. The fee is between $55 and $165.

Keep in mind that while you buy these open seats in advance, there’s no guarantee they will stay free until you depart.

If another passenger buys a ticket at the last minute, and your seat — or row — fills, you’ll get a refund.