There are about 800 logs in a cord of firewood. The exact number varies with the size of logs. If the logs are larger then there may be 400, and if smaller there may be 1200.
A Cord is a volume measurement, 4ft x 8ft x 4ft deep. A log is usually 16 inches long, so 3 make 4ft.
A face cord is 4ft x 4ft x 16 inches or 1/3 of a full cord and is about the same a rick of wood, has about 300 pieces.
A bundle has about 6 pieces.
The word cord dates back hundreds of years when a rope was used.