There are six Grand Sumo tournaments (or honbasho) each year: three in Tokyo, and one each in Osaka, Nagoya and Fukuoka. Tournaments are held every other month starting in January. Each tournament begins on a Sunday and runs for 15 days, ending also on a Sunday. Each sekitori ranked wrestler has one match per day, while the lower ranked rikishi compete in seven bouts, approximately one every two days.

Each day is structured so the highest-ranked contestants are matched up at the end of the day. Thus, wrestling will start in the morning with the Jonokuchi wrestlers and end at around six o'clock in the evening with bouts involving the Yokozuna. The wrestler who wins the most matches over the fifteen days wins the tournament championship. If two rikishi are tied for the top, they wrestle each other and the winner takes the title. Three-way ties for the top position are rare, at least in the top Makuuchi division. In these cases the three wrestle each other in pairs with the first to win two in a row taking the tournament. More complex systems for championship playoffs involving four or more rikishi also exist, but these are usually only seen in determining the winner of one of the lower divisions.

A Makuuchi rikishi will arrive at the stadium in the afternoon and enter the changing room. There are 'East' and 'West' rooms so competing wrestlers do not meet their opponent of the day prior to the match. He will change first into his kesho-mawashi, an ornate, embroidered silk 'apron', which he will wear during the ring entering ceremony, or dohyo-iri. There are four dohyo-iri on each day, two for Juryo and two for Makuuchi ranked wrestlers. In each case there is one for those in the east changing room and one for those in the west. During the ceremony the rikishi are introduced to the crowd one by one in ascending rank order and form a circle around the ring facing outwards. Once the highest ranked wrestler is introduced they turn inwards and perform a brief ritual before filing off and returning to their changing room. Yokozuna have a separate dohyo-iri; see Yokozuna.

Once in the changing room the wrestlers change into their fighting mawashi and await their bout. The wrestlers enter the arena again two bouts prior to their own and sit down at the side of the ring. When it is their turn they will be called into the ring by a yobidashi and they will mount the dohyo. The referee or gyoji will coordinate the bout. On mounting the dohyo the rikishi performs a number of ritual moves involving leg stomps and clapping whilst facing out towards the audience. He also cleans his mouth out with so-called chikara-mizu or power water. He then throws some salt into the ring to purify it. The rikishi perform another brief ritual when facing each other and then adopt a crouch position to "charge" at each other (called the tachi-ai). The wrestlers do not need to charge on the first occasion but can instead stare and return to their corner. This can happen a number of times (about four) until on the last occasion the gyoji informs them they must start the bout. The total length of time of this preparation and attempts to psyche themselves or opponents is four minutes for all rikishi, but in the lowest divisions the wrestlers are expected to start more or less immediately.

At the tachi-ai both rikishi must jump up from the crouch simultaneously at the start of the bout, and the gyoji can restart the bout if this does not occur. Once the bout is complete the gyoji must point his gunbai or war-fan towards the winning side. The rikishi will return to their start positions and bow to each other before retiring, a winning rikishi may receive additional prize money in envelopes from the gyoji if the matchup has been sponsored. The gyoji is obliged at the end of the bout, even in bouts too close to call, to immediately designate a preliminary winner. For all matches, there are five shimpan (judges) around the ring who can query the gyoji's decision. If this happens they will meet in the centre of the ring to hold a mono-ii (lit: a talk about things). After reaching a consensus they can uphold or reverse the gyoji's decision or order a rematch, known as a torinaoshi.

In contrast to the time in bout preparation, bouts are typically very short, usually less than a minute, and often only a few seconds. Extremely rarely a bout can go on for many minutes, in which case the gyoji may call a mizu-iri or water break. The wrestlers are carefully separated, have a brief break and then return to the exact position they left off in. It is the gyoji's responsibility to do this. If after a further few minutes they are still deadlocked they can have a second break, after which they start from the very beginning. Further deadlock with no end of the bout in sight, can lead to a draw, which is an even rarer result.

The last day of the tournament is called senshuraku, which literally means the pleasure of a thousand autumns. This colorful name for the culmination of the tournament echoes the words of the playwright Zeami to represent the excitement of the decisive bouts and the celebration of the victor. The Emperor's Cup is presented to the rikishi who wins the top division (makuuchi) championship. Numerous other (mostly sponsored) prizes are also awarded to him. These prizes are often rather elaborate, ornate gifts, such as giant cups, decorative plates, and statuettes.

Promotion and demotion are determined by a wrestler's score over the 15 days. The term kachikoshi indicates a record having more wins than losses, as opposed to makekoshi, which indicates more losses than wins. In the Makuuchi division, kachikoshi means a score of 8–7 or better, while makekoshi means a score of 7–8 or worse. A wrestler who achieves kachikoshi will almost always be promoted further up the ladder, the size of promotion being higher for better scores. Similarly, makekoshi almost always results in a demotion. In the sanyaku ranks simple kachikoshi are often not sufficient to be promoted. Rikishi in this highly competitive subgroup of the highest division may require at nine, ten, or even eleven out of fifteen possible wins to gain in rank. There are special rules for Ozeki and Yokozuna promotions.

A top division wrestler who is not an Ozeki or Yokozuna and who finishes the tournament with kachikoshi is also eligible to be considered for one of the three sanshō prizes awarded for technique (ginōshō), fighting spirit (kantōshō), and for the defeating the most Yokozuna and Ōzeki (shukunshō).