The slug is defined as the mass which would accelerate at a rate of 1 ft/s² under a force of one pound-force (lbf). Since 1 lbf is the force exerted on a mass of one pound by a standard gravitational field (of exactly 9.80665 meters per square second), a slug is thus exactly equal to 196133/6096 pounds (about 32.1740485564 lb or 14.593902937206 kg).
Source: wiktionary