Weightlifting athletes compete in bodyweight categories, or weight classes, for competitive fairness. In 2018, the International Weightlifting Federation announced a new slate of weight classes for the Tokyo Olympics. The seven men’s and women’s weightlifting classes of the Olympic program are as follows: 

Two hours before the start of a competition, every participating athlete must weigh in to ensure they do not exceed the weight limit for their class. At the weigh-in, a coach writes on the competitor's card how many kilograms his or her initial attempt will be for each round (the snatch and the clean and jerk).

Fourteen athletes compete in each weight class, split into two groups based on previous combined personal record. Those with higher PRs make up Group A, while remaining athletes make up Group B. Group B completes both rounds of competition before Group A begins.  

For either group, the athlete who requests the lowest starting weight is called to the platform first. Weight is added to the bar progressively and can only be increased, never decreased. Athletes lift in order of requested weight until each lifter has made three attempts.  

Often, the weaker lifters in the group complete all three of their attempts before the top contenders make any of theirs, if the top contenders request a starting weight greater than what the weaker lifters are comfortable attempting. Except for the first attempt, which must be declared at the weigh-in, athletes (or their coaches) can alter the requested weight right up until the athlete's name is called for the platform.  

Once an athlete’s name is called, he or she has one minute in which to make a good lift. In the event when an athlete must make two attempts in a row, a two-minute time period is allotted. There is a 10-minute break in between the snatch and clean and jerk rounds.

The final ranking is tabulated by adding each weightlifter’s best snatch and clean and jerk lifts. Because it is a combined event, a lifter may finish in a position other than first in either or both of the disciplines and still come away as the overall champion.  However, it is most common that the overall winner has the best lift in at least one of the disciplines. 

In the event of a tie for a medal, the athlete with the higher snatch total is ranked higher. If the snatch totals are equal, the athlete who achieved the clean and jerk result in the fewest attempts gets priority.  

In Olympic weightlifting, three referees evaluate each lift. Once a referee makes a decision, he or she presses a white (good lift) or red (no lift) button on the scoring device. When a button is pressed, a light appears, corresponding to the color of the button. As soon as two of the three referees have made the same decision (white or red), a visible and an audible signal is given to the lifter, indicating he or she can lower the barbell.

During the Olympic weightlifting competition, a five-member jury monitors the referees to ensure that the rules are correctly adhered to. The jury may reverse a referee's decision only if the following occurs: 

1.  The jury unanimously agrees that there has been a rule breach. 
2.  The jury unanimously agrees to reverse the decision. 

If the jury is not unanimous on both accounts, then the referee's decision stands.