Answer: 1.5 Tons

Over half a century ago, Popular Mechanics offered what was, for the time, a generous estimate of the future state of computing. In the March 1949 edition of the magazine, they predicted:

Where a calculator like ENIAC today is equipped with 18,000 vacuum tubes and weighs 30 tons, computers in the future may have only 1,000 vacuum tubes and perhaps weigh only 1.5 tons.

Although it’s easy to chuckle at the technological predictions of yesteryear, we can forgive the writers of Popular Mechanics for their overly conservative weight estimate. In 1949, computer calculations were performed by vacuum tube arrays. Reducing an array from 18,000 components to 1,000 components while maintaining similar computational power (or even increasing it) would require more than a few advances—the future of computing looked bright to the writers, albeit still a bit bulky. What they couldn’t have foreseen then was the advent of the microprocessor.

The invention and widespread commercial deployment of the microprocessor in the 1970s changed the volume of space required for computing and touched off a race to continually increase the amount of computing power on the tiny silicon chips. Now a single microprocessor, millions of times more powerful than ENIAC, can be balanced upon a fingertip and ultra-light computers and smartphones can be slipped right into our bags and pockets—no crane required.