Overview

A single-elimination tournament, often called a knockout or sudden-death format, is a competition in which a participant is removed from contention after losing one match. Competitors are paired in rounds and winners advance while losers are eliminated, continuing until a single champion remains. The simplicity and decisive progression make this format widely used across sports, games and elimination cups.

Format and mechanics

Brackets are organized so that the number of entrants fits into successive rounds. The number of rounds is the smallest integer r for which 2^r is at least the number of entrants (often written as ceil(log2(n))). If the field is not a power of two, byes are assigned in the first round so some participants automatically advance. Pairings may be determined by seeding (ranking participants to spread stronger competitors) or by random draw. Ties are resolved according to the sport’s rules (extra time, penalty shootouts, tie-break games).

Uses and examples

Knockout stages appear in many sporting events and tournaments: cup competitions in team sports, the elimination phase of multi-stage tournaments, and many individual-sport championships. Examples include national cup tournaments, the final stages of international competitions after group play, and single-elimination brackets in amateur and e-sports events.

Advantages and disadvantages

  • Advantages: fast resolution, easy scheduling, clear drama and high stakes in each match.
  • Disadvantages: a single bad performance eliminates a competitor, which can reduce fairness for assessing overall ability; fewer matches mean less revenue or practice opportunities.

Variations and notable facts

Common variations include double-elimination (players must lose twice to be eliminated), consolation brackets for ranking lower places, and reseeding between rounds to match highest remaining against lowest remaining. Seeding and byes are important tools to balance competitive integrity and logistical constraints. Because of its directness, single-elimination remains a popular choice when organizers need decisive results with limited time or resources.