A trillion is commonly defined as a million millions. It is written as 1,000,000,000,000, or 1012. The original definition of a trillion, that is still used in some non-English-speaking countries, defines the trillion as 1018. In American and British English however, trillion refers to the former definition of 1012. In scientific notation, this is written as 1 × 1012.

How big is a trillion?

A trillion is a number so large that it can be difficult to relate to our everyday lives. For example, when saying "1 trillion" or seeing 1,000,000,000,000, although we know that it is a large number, it may not necessarily feel that way. If we think about it in terms of seconds, we may get a better sense of how large a trillion actually is.

1 trillion seconds is equivalent to 16,666,666,666.667 minutes, which is equivalent to 277,777,777.778 hours, which is equivalent to 11,574,074.074 days, which is equivalent to 31,709.79 years, which is quite a long time. In terms of human lifespan, no human can live anywhere near as long as 1 trillion seconds.


A Boeing 737-800, one of the more common types of planes that you may have seen or flown on, is considered an average sized plane. It weighs around 90,000 pounds when empty. Assuming they are empty, how many 737s would it take to make up 1 trillion pounds?

1,000,000,000,000 pounds ÷ 90,000 pounds per plane ≈ 11,111,111 planes

That's over 11 million planes! It may still be difficult to imagine how much space this many planes would take up, so let's look at it another way. Total movements is one of the measurements of how busy an airport is. A "movement" in this context refers to an aircraft taking off or landing. In 2017, the busiest airport in the world was Hartsfield-Jackson Atlanta International Airport, which had 879,560 total movements that year. If this number stays the same, how long would it take for over 11 million planes to take off or land from the airport?

11,111,111 planes ÷ 879,560 total movements per year ≈ 12.63 years

So, to put how large a trillion is into perspective, it would take over twelve and a half years for the equivalent of 1 trillion pounds of planes to fly in or out of the busiest airport in the world. Think about all the things you can do in twelve years!