80/20

80/20 or 80-20 may refer to:
 * 80/20 housing, housing of which 20% is "affordable", encouraged by regulation in the U.S.
 * 80-20 rule or the Pareto principle
 * 80-20 Initiative, an Asian American political organization
 * 80/20 Thinking, a UK Privacy consultancy firm
 * T-slot structural framing, a framing system sometimes known as "80/20 framing" (80 by 20 mm) after one manufacturer