These rules are from the web site but have been modified for the Catholic Master Builders SUMObot events.  This change was made in order to allow the use of standard EV3 MINDSTORMS kits and to stay with the rule of only being able to construct with LEGO branded parts on your EV3 MINDSTORMS SUMObot.

Section 1: SUMObot

The overall SUMObot contest is structured using a double elimination tournament format, where each robot must lose two matches to be eliminated from the tournament.
A SUMObot match involves two contestants whose robots operate in the sumo ring according to the game rules presented here.
The match continues until four SUMObot points are scored by one of the contestants over several games.

Section 2: Playing Field Specifications

The playing field is a raised circle with the dimensions as shown below.

  • Diameter: 36 Inches

  • Border line: 1.25 Inches

  • Starting line width: 0.5 Inches

  • Starting line length: 4 Inches

The top surface is flat and smooth. The surface will be gloss-white in color. 
The starting lines are two parallel red lines centered on the field. 
The outer edge of the field, the border line, is a black circular ring. 


Fields may be constructed using painted sheet materials, purchased online as a sticker, or as a completed field with supports.

Section 3: SUMObot Robot Specifications (common)

  • The robot must be able to fit inside a 7" x 7" square box with no height limit.

  • The Robot must be made ENTIRELY out of LEGO Bricks and LEGO branded pieces.

  • A maximum of 1 EV3 Mindstorm brick for control, 3 motors for movement or for an optional tool can be used.

  • All actions must be totally pre-programmed. The use of any form of remote control is prohibited.

  • The robot must be designed to wait five seconds after the contestant presses the robot's RUN button.

  • The robot will not include any parts that might damage or deface the playing field.

  • The robot will not include any part that fixes the robot to the playing field surface. 

  • The robot must always move after the beginning 5 seconds wait time..

See the definition of different SUMObot classes.

Section 4: Game Principles

A standard match consists of three games of up to three minutes each. The first contestant to win four SUMObot points is the winner of the match.
If no player has 4 SUMObot points at the end of three games, the player with the most points wins.
If both players have the same number of points after three games the referee can call a winner, or choose to run one additional game.

Section 5: Game Procedure

Beginning of the Game

  • Before the game, the contestants greet each other outside the playing field following the chief referee's instructions, and then enter the playing field. The contestants can place their robot anywhere behind their starting line. No part of the robot can be in front of the starting line before the match begins.

  • At the referee’s signal, the contestant presses a single button on the EV3 robot. The game begins five seconds after the referee’s signal. The contestants must exit the playing field during this 5 second period.

  • Prior to the start of a match, the entire robot must still meet the size to fit in the square box as defined for the weight class. At any time after the start of the match, the robot can expand outside these dimensions.

End of the Game

  • The game ends when the referee calls the winner. Both contestants should thank each other for a fair and competitive match after removing their robots.

A Game will be stopped and a rematch will be started under the following conditions:

  • The robots are locked together in such a way that no more action appears to be possible, i.e. they have rotated in circles for 30 seconds or more.

  • Both robots touch the exterior of the playing field at the same time.

  • Any other conditions under which the referee judges that no winner can be decided.

  • In case of a rematch, maintenance of competing robots is prohibited, and the robots must be immediately placed in the designated starting position.

  • If neither of the competing robots win, or lose, after a rematch, the referee may reposition both robots to a specified location and restart. If that does not yield a winner, the match may continue at any location decided by the referee, until the time limit is reached.

Section 6: Scoring SUMObot Points

Two SUMObot points are awarded for a Victory. The following conditions define a Victory:

  • When a robot ejects its opponent from the playing field with a fair action. The robot is considered ejected the moment ANY part of the robot touches the exterior of the playing field. A robot hanging over the edge of the playing field or only touching any part of the cylindrical side of the playing field is not considered ejected, and the robot is still in play.

  • When the opponent's robot goes out of the playing field on its own for any reason.

  • When the opponent's robot stops moving on the playing field for more than 10 seconds.

  • If the opponent's operator interferes with either robot, or the field, during the match.

One SUMObot point is awarded for an Advantage. The following conditions define an Advantage:

  • An opponent's operator fails to start their robot at the referee’s command (false start),

  • The opponent's preparation for the start of the next match takes more than 30 seconds.

  • Parts of the opponent's robot (weighing more than 1 ounce), are separated and dropped from the robot.

  • Any other actions which occur that are deemed unfair by the judge.


Section 7: Violations

A contestant who takes any of the following actions will be disqualified from the game:

  • A contestant does not attend the appointed playing field when called at the beginning of the game.

  • A contestant ruins the game, such as by intentionally breaking, damaging, or defacing the playing field.

  • A contestant's robot does not meet the robot specifications.

  • A contestant displays unsportsmanlike behavior.

  • A contestant intentionally injures the opponent’s operator.


SUMObot Classes and Rules

Depending on the resources available at your particular SUMObot competition, your SUMObot will have to conform to one or more specific "Class" specifications. These classes are set up to permit fair competitions between all the teams.

The specific classes all share a set of "common rules" as follows:

Common Class Rules

  • The Robot must be made ENTIRELY out of LEGO parts.

  • A maximum of 1 EV3 Minstorm brick for control and 3 motors for movement/actuation can be used.

  • The robot must fit inside a 7" x 7" square box (no height limit) when it is in it's starting configuration.

  • The robot must weigh no more than 2 pounds when in it's starting configuration.

  • The robot must be designed to wait five seconds, after the contestant presses a start button, before it moves.

  • The robot must use the standard LEGO programming provided for the LEGO MINDSTORMS EV3 kit.

  • All actions must be totally pre-programmed. The use of any form of remote control is prohibited.

  • The robot will not include a device that obstructs the control of the opponent’s operation, such as a jamming device or strobe light.

  • The robot will not include any parts that might damage or deface the playing field.

  • The robot will not include any part that fixes the robot to the playing field surface. 

  • The robot must always move after the five second waiting period of the start of the match.

In addition, each SUMObot Class adds one or more extra rules, as follows:

Limited Parts Sub-Class:

  • The robot may only be constructed from a specific subset of LEGO parts. This subset is defined by the event organizer prior to the competition. An example might be: "Only those LEGO items found in a retail LEGO MINDSTORMS EV3 kit" or perhaps "any component located on the Parts Table".

Common Program Sub-Class:

  • The robot must use the specific program provided by the event organizer. Any strategy options must be identical for all participants (eg: different speeds, and turn rates)

Open Program Sub-Class:

  • The robot can use the standard LEGO program provided for the LEGO MINDSTORMS EV3 kit and/or additional programming methods.

Open Weight Sub-Class:

  • The robot can weigh whatever weight when in it's starting configuration as determined by the tournament organizer.


We are grateful that the web site has so many resources and passion for Sumo Bots. Please visit their web site to get ideas and to see what they are up too. Note that our Catholic Master Builders SUMObot events will use our modified sumo bot rules and guidelines for the purpose of teaching and guiding EV3 MINDSTORMS owners with a fun activity and promoting STEM learning towards being part of a FIRST LEGO LEAGUE team.