What is the most common language spoken worldwide?

Answer 1

English! Although 1.2 billion people speak Chinese worldwide, English is most common.

Actually, it depends on where you draw the line. How well do you have to know a language to be considered to speak it? I can say a few things in Japanese, but I'm not good enough to be counted as a "Japanese speaker."

A lot of people speak English well enough to do business with American tourists, or to read a technical article, or to place an order with a company in Another Country where they don't speak the same language, but both know enough English to mostly understand each other. But that's not the same as fluency.

So depending what your standards are, the answer could be either Mandarin Chinese, or English (if you include broken English).

Answer 2

The most common language spoken worldwide is Mandarin Chinese, with over a billion native speakers.