The symbol to look for when buying flights that could get you money back

A NEW online booking tool could mean passengers never pay more than they should for plane tickets ever again.

There's nothing more frustrating than finding out that your airfare could have cost a lot less than what you paid for it, had you just waited a few days - but that feeling could soon be a thing of the past.

Google is trialling a new booking system that would see people refunded if the price of their flight drops after they have bought their ticket.

The search engine will monitor the prices of flights booked via their online booking system Google Flights, and then pay back the difference if there's a drop.

Currently, Google is testing the system on certain flights in the United States, on only three airlines — Alaskan, Hawaiian and Spirit.

Holidaymakers will be able to spot the qualifying flights by looking for a blue “price-guarantee” badge.

Anyone whose eligible flights dip in price will receive an email notification telling them their funds were automatically deposited in their Google Pay account.

Travellers will need to have one of those set one up in order for all the system to work.

Money from Google Pay can then be transferred to a linked bank account.

Jade Kessler, product manager at Google Flights said that they want to expand this far beyond the current trial in the future.

She : “What we’re wanting to do is to take [our] price insights to the next level.

"We have hopes to offer this to as many users as possible and expand it beyond just Book on Google.”

The new tool isn't the only way people can save money on flights using Google.

Fox News' "CyberGuy" Kurt Knutsson explained how to use the site to avoid paying too much for flights.