Amazon Prime comes with plenty of perks, the main one being the free, fast shipping offered on most purchases. But would customers be willing to pay extra for the service? We'll soon find out, as the price is going up in the US from $99 to $119.

Amazon chief financial officer Brian Olsavsky revealed the hike in an earnings call yesterday. It's the first time in four years that the annual subscription has gone up, though monthly Prime members, who have the benefit of being able to cancel whenever they want, saw their fees increase from $11 to $13 in January.

The updated price will come into effect for new members on May 11. Current subscribers whose annual renewal date is before June 16 can get another year of Prime at the current lower rate, but if renewal lands on or after that date then it will cost $119.

Following its introduction in 2005, Prime's annual membership fee has seen only one increase, going from $79 to $99 in 2014.

The news comes just a week after Jeff Bezos revealed for the first time the official number of worldwide Prime subscribers. Previously, it had been left to analysts and market research firms to estimate the figure, which was put somewhere between 60 million and 90 million last year, but the CEO said there are actually over 100 million paid Prime members worldwide. With the US being Prime's biggest market, tens of millions of people can expect to see their annual fee go up.

While the new price works out at under $2 extra per month, it'll be interesting to see how many people now decide not to renew their membership as a result of the increase.