How many Lego bricks have been made?

How to get close to this number

Work from sets and households. Hundreds of millions of households have owned a set, a typical set contains hundreds of pieces, and production has run for six decades. Households times pieces times repeat purchases produces a figure in the hundreds of billions, which is the right scale.

The per-person framing is the sanity check: more than a hundred bricks for every person on Earth. That is the kind of number that sounds impossible until you consider that a single large set exceeds it on its own, and that production has been continuous since the 1950s. Cumulative manufacturing totals for a long-lived product always outstrip intuition.

The compatibility fact in the explanation is the one worth keeping, and it is a genuine engineering achievement rather than a marketing claim. A brick moulded in 1958 still clutches a brick moulded today, which requires holding a moulding tolerance of a few hundredths of a millimetre across six decades and dozens of factories. No software platform has maintained backward compatibility for anything like that long.