There are 1.65 trillion barrels of proven oil reserves in the world as of 2016.
The world has proven reserves equivalent to 46.6 times its annual consumption levels. This means it has about 47 years of oil left (at current consumption levels and excluding unproven reserves).
This means that the oil is going to run out in our lifetime
Source/more reading: https://www.worldometers.info/oil/
Update: It is infact not true (or just partially true), because it only considers already known oil reserves that can be pumped out with current technology.
There is more oil that can potentially be used as technology and infrastructure advances, so the estimate of 50 years is wrong.
For the correction thanks to Cephalotrocity@biglemmowski.win (their original comment)
I remember when they said there were 30 years left in the '90s.
Yeah, not trying to poke holes, but I was hearing “less than 50 years left” when I was in school in the 2000s. I do remember seeing a post here and there about new oil reservoirs being discovered but never any follow up. So I suppose that could be stretching things out. But oil use certainly hasn’t decreased in the last 25 years.
By 2050, there might even be 70 years of oil left!