How many years are left until oil runs out?

How many years left until oil runs out depends on reserves, consumption, and technology, but estimates vary. Proven reserves are about 1.7 trillion barrels, at current consumption of about 100 million barrels per day or 36.5 billion barrels per year, simple division suggests about 47 years left, often quoted as 40 to 60 years. However, this does not mean oil runs out completely in 47 years, as new reserves are found, extraction technology improves, and unconventional oil like shale and oil sands become recoverable, extending timeline. Also demand may decline due to electric vehicles and renewables, extending years left. Some estimates with all recoverable resources including unconventional suggest 70 to 100 years. Peak oil theory suggests production may peak before reserves run out, making oil more expensive and harder to extract. So oil will not suddenly run out, but easily accessible cheap oil will become scarcer, leading to higher prices and transition. So roughly 40 to 60 years of proven reserves at current consumption, but likely longer with new technology and reduced demand, and complete exhaustion not expected for many decades to over a century.