Microwave Oven Invented
Percy Spencer accidentally discovered microwave cooking while working on radar technology
October 08, 1945
An Accidental Discovery in a Lab
The microwave oven was invented by accident. In 1945, Percy Spencer, an engineer at Raytheon Corporation working on radar technology, noticed that a chocolate bar in his pocket had melted while he was standing near an active magnetron — the device that generates microwave radiation. Intrigued, he experimented with other foods, including popcorn and an egg (which exploded). Spencer realized that microwave radiation could heat food far faster than conventional methods. He quickly filed for a patent, and Raytheon introduced the first commercial microwave oven in 1947.
From Industrial Machine to Kitchen Appliance
The first commercial microwave oven, called the Radarange, was enormous — about 6 feet tall and weighing nearly 750 pounds. It cost about $5,000, making it practical only for restaurants, railroads, and large food service operations. Through the 1950s and 1960s, the technology was refined and costs fell. The introduction of compact countertop models in the late 1960s, priced under $500, began the appliance's journey into home kitchens. By the mid-1970s, prices had dropped below $200 and sales were taking off. By 1975, more microwave ovens were being sold in the United States than gas ranges.
Changing How the World Eats
The microwave oven fundamentally changed food culture. It enabled the frozen food industry to grow dramatically, making convenience meals a staple of modern life. It changed home cooking habits, reduced reliance on stovetops for reheating, and accelerated the pace of daily life. Today microwave ovens are found in about 90 percent of American households and are common worldwide. The technology itself — microwave radiation for heating — has also found applications in industrial drying, wood treatment, and medical procedures. Use the date calculator to see how many decades have passed since Spencer's accidental discovery.