Mahjong Tile Efficiency Guide | Shanten, Ukeire, and Five-Block Examples

Distance to tenpai and effective tiles

Shanten is the number of steps a hand is from tenpai. Tenpai is 0-shanten, a hand one step from tenpai is iishanten, and a complete hand is treated as minus 1.

A tile that reduces the distance by one step when drawn next is an effective tile. The total number of effective tiles remaining is called the ukeire count. If there are at most 4 3m and 3 6m remaining, the maximum ukeire is 7 tiles.

The act of choosing and discarding one tile on your turn is called dahai. When comparing discard candidates, count the distance of the entire 13-tile hand remaining after each discard. Two identical tiles form a pair (toitsu). The ukeire count helps compare candidates at the same distance, but the number alone does not determine every discard.

Seven pairs and thirteen orphans each have their own way of measuring distance, separate from a standard complete hand. If a hand contains many pairs or many terminals and honors, keep these special hand shapes in consideration instead of assuming only the standard shape.

Count the remaining tiles using visible information

There are 4 copies of each tile, including the red five. To count how many of a tile remain, subtract from 4 the copies in your hand and those visible in all players’ discards, open calls, revealed indicator tiles, and other public information. If you have 1 2m and can see 2 more 2m in the discard areas, at most 1 unseen 2m remains.

This calculation gives the maximum based on visible information. Unseen tiles may be in other players’ hands or the dead wall, so they are not necessarily all left in the live wall. Treat this as an estimate for comparing candidates using the same public information.

First list each effective tile type without duplication, then add the remaining copies of each type. In a compound shape, one tile can improve more than one block. Even if 3m improves two taatsu at once, there are still at most four copies of 3m, not eight.

Build five blocks from a complete hand

A standard complete hand requires four completed groups of three or four tiles and one pair of identical tiles. Each completed sequence, triplet, or quad is a group (mentsu), and the pair that forms the head is the pair (jantou).

An incomplete two-tile shape is also counted as one block that may later become a group. The five-block method views the hand as five blocks that will become four completed groups and one pair.

For example, with “123p, 456p, 789s, East East, 45m,” there are three completed groups, one jantou candidate, and one candidate for the final group. Adding 3m or 6m to 45m completes the fourth group, allowing East East to serve as the jantou.

If you have six block candidates, you will eventually remove one. At this stage, do not decide by tile count alone; compare how easily each block can be completed, its connection to dora and yaku, and its value as a safe tile. If you have only four candidates, leave room to form a new two-tile group from tiles not yet in a block.

Two identical tiles can serve as either the pair or part of a three-tile group. Treating every possibility as a separate completed block leads to double-counting, so reassess each tile’s role after every draw. Seven Pairs and Thirteen Orphans have different structures, so do not force them into the five-block framework.

Identifying one-shanten shapes from the tiles

Even at the same one-shanten, the effective tiles vary depending on whether the hand has a pair and how many incomplete two-tile groups it contains. In the following diagrams, first identify the completed parts, then examine the highlighted incomplete parts.

A shape with a pair and two incomplete parts

45p completes with 3p or 6p, while 56s completes with 4s or 7s. Drawing 7p lets you form a three-tile group of 7p and use the two 5s as the pair; drawing 5s reverses those roles. A shape with a pair and two possible groups that reaches tenpai when either group completes is called perfect one-shanten.

A shape without a pair

Drawing 1m or 4m completes 23m, allowing you to discard one tile from 67s and create a single-tile wait. Drawing 2m or 3m makes the matching pair your head and leaves 67s as the wait. The same changes occur with 67s, so both tiles that complete a two-tile group and tiles that pair one of its tiles are effective. This pairless shape is called headless.

A shape with three completed groups, a pair, and two unconnected tiles

A shape with three completed groups and a pair, but with the remaining two tiles not yet forming a group, is called floating-tile one-shanten. 2m through 6m connect to 4m, while 5m through 9m connect to 7m. Since 5m and 6m work with both, count them only once; because the hand contains one 4m and one 7m, 3 copies of each remain. The other 6 types have 4 copies each, giving up to 30 number tiles. Since the hand already contains 2 East tiles, 2 remain. Drawing East forms a three-tile group; discarding either 4m or 7m then creates a single-tile wait on the other. Together, the number tiles and East total up to 32 effective tiles.

Middle number tiles offer more possible changes, but which tiles to keep depends on visible tile counts, dora, and potential yaku.

The 556s above can be used as either 55s or 56s. A shape that can be divided in two or more ways is called a compound taatsu. It accepts 4s or 7s to form a three-tile group, as well as 5s to make a pair, so list the tiles without counting any twice. The specific names for these shapes are introduced in the following comparison.

34567m can also be divided in two ways: “345m and 67m” or “34m and 567m.” In this five-tile run, fixing 345m as the completed part overlooks the 2m and 5m side, while fixing 567m overlooks the 5m and 8m side. Read the tile sequence first, re-evaluate the remaining 13 tiles for each possible split, and only then name the shape to avoid counting errors.

Incomplete shapes and maximum tile counts

A consecutive two-tile group such as 45 completes with either outside tile and is called a ryanmen. A gapped group such as 46 completes with the tile in the middle and is called a kanchan. An edge group such as 12 or 89 completes only on the inside and is called a penchan. A tile not connected to any group is an isolated tile.

The following four examples are 13-tile tenpai shapes with three complete groups and a pair. Only the final incomplete part changes, and unless otherwise noted, no copies of the tiles are visible outside the hand. In each diagram, check the colored section and the maximum number of tiles remaining that complete it.

45m: up to 8 tiles, 3m and 6m

Because it can accept two outer tile types, it has more acceptance than a single-tile wait when the same number of tiles are visible. The 556s in the complete iishanten shape above is a ryanmen pair, serving as both a 55s pair and a 56s ryanmen.

46m: up to 3 copies of 5m

The colored 46m is completed only by 5m. In this example, one 5m is visible, so at most 3 remain. A red 5m also counts as one 5m and is not added as a separate tile type.

12m: up to 4 copies of 3m

The colored 12m can only be completed by 3m. While 23m can accept 1m and 4m, 12m cannot accept 0m because no such tile exists. An 89 shape likewise waits only for 7. Although both are single-tile waits, their potential changes after drawing nearby tiles and their connections to yaku differ from a kanchan.

Two pairs: up to 4 tiles, East and 5m

Draw either East or 5m to make a three-tile group, leaving the other as the pair. Although there are two tile types, two copies of each are already used, so at most 4 tiles remain in total. If East is your seat wind or the prevailing wind, it may provide a yaku, changing its value beyond tile count alone.

Tiles closer to the center have more ways to develop

Early in the hand, before you have five blocks, compare how easily isolated tiles can form two-tile groups. An isolated 5m connects with 3m, 4m, 5m, 6m, and 7m. With one 5m in hand and no exposed tiles, four copies each of 3m, 4m, 6m, and 7m remain, plus three copies of 5m, for a total of 19 improving tiles.

For an isolated 1m, another 1m forms a pair, 2m creates a 1m2m penchan, and 3m creates a 1m3m kanchan. If you hold one 1m and none of these tiles are otherwise visible, up to three 1m, four 2m, and four 3m remain, for 11 useful tiles in total. Middle tiles connect to more neighboring numbers and generally offer more ways to improve.

The 19 and 11 tiles counted here are improving tiles that let an isolated tile form a two-tile shape. They are distinct from strict ukeire because they do not necessarily reduce the shanten of the whole hand. If you already have five blocks, a tile that creates a new taatsu may not advance the hand and may instead leave you with six blocks.

The order for comparing candidates in actual play

First, determine whether a standard hand, chiitoitsu, or kokushi musou is realistic. For a standard hand, split consecutive tile sequences in multiple ways to identify candidates for five blocks. Then compare the following four factors in order.

1. Distance to tenpai: Compare the shanten count after discarding each candidate.
2. Number of tiles accepted: For candidates at the same shanten, list all effective tiles without duplicates, then subtract the copies visible in your hand and public information from four of each.
3. Quality after improvement: Compare the wait, yaku, and value when the hand reaches tenpai.
4. Current situation: Check tiles usable for defense, opponents’ calls, turns remaining, dealer/non-dealer status, and the score gap.

Do not maximize ukeire alone

Tile efficiency measures how quickly a hand approaches completion, but the goal is not to maximize ukeire on every turn. Among candidates at the same shanten, the widest option is often a strong starting point, but hand value, deal-in risk, and the game state can change the decision.

Hand value and yaku

If discarding dora adds two effective tiles but keeping it preserves mangan potential, you are trading speed for value. The tiles you keep also affect yaku such as tanyao, pinfu, sanshoku doujun, ittsuu, and honitsu. Use the Riichi Mahjong Yaku Guide to check closed-hand requirements and open-hand reductions.

Safety and game state

Late in the hand or after an opponent declares riichi, avoiding a deal-in matters alongside speed. Discarding honor and edge tiles early may improve efficiency but leave fewer safe tiles later. Base push-fold decisions on shanten, wait quality, hand value, the hand number, dealer status, and point gaps; see the Mahjong Defense and Push-Fold Guide.

Calls and the yaku that remain afterward

A yakuhai pair has only two remaining copies, but you may pon one when another player discards it, completing both a group and a yaku. A closed ryanmen taatsu may have wide ukeire, yet calling chii can remove a closed-hand-only yaku. Consider live-wall draws, tiles you can call from other players, and the yaku that remain after a call as separate factors.

Shape after effective tiles

Also consider the shape left after drawing an effective tile. Two candidates may each accept eight tiles now, yet one may lead mostly to ryanmen waits while the other leads to tanki or edge waits. Compare both current ukeire and the quality of the next shape.

Treating tile efficiency as “always choose the largest count” can conflict with practical goals. Narrow the candidates by shanten and tile count, compare their quality after improvement, then factor in value, defense, visible tiles, turns remaining, and the hand and score situation.

How to practice tile efficiency

Start by counting waits in tenpai shapes. A ryanmen has two tile types, a kanchan or penchan has one, and a wait from two pairs has two types but no more than two copies of each. Subtract visible copies in your hand and the discard area every time. Once you can count waits quickly, move on to discard candidates at 1-shanten.

Next, save one discard decision that made you hesitate and rearrange the 14 tiles after the game. For each candidate, write down the shanten after discarding, the effective tile types and remaining copies, the resulting wait after improvement, and any yaku or dora you would lose. The useful result is not a single universal answer, but an explanation of which conditions change the choice.

After recording the acceptance count, do not judge the choice solely by whether the hand actually won. Record the tiles visible when you discarded, the resulting shape, value, and safety, then review which conditions changed the order of the candidates.

Common counting mistakes

• Failing to subtract tiles in your hand: A pair can become a triplet with at most two remaining copies because two are already in your hand.
• Ignoring visible tiles: Two effective tile types do not always mean eight remaining tiles; subtract copies visible in hands, discard areas, open melds, and indicators.
• Counting a red five as a fifth copy: A red five is one of the four copies of that five.
• Counting the same tile twice in a compound shape: Even if 3m improves two blocks, there are still at most four copies of 3m.
• Calling every improving tile an effective tile: Separate tiles that make the shape more flexible from strict ukeire that reduces the shanten of the whole hand.
• Fixing the five blocks too early: Consecutive shapes can be split in several ways, and a pair may serve as either the head or a triplet candidate.
• Choosing a discard by tile count alone: Ignoring yaku, hand value, safety, and the game state can produce a choice that does not serve the hand’s purpose.

Summary: Think in the order of distance, number, quality, and situation

The starting point for tile efficiency is to reduce the shanten after discarding. If candidates leave the same shanten, list each effective tile type, subtract the copies in your hand and visible in public information from four, and compare the remaining ukeire. Organizing a standard hand as five blocks—four groups and one pair—makes extra or missing blocks easier to spot.

45m accepts up to eight tiles—3m and 6m; 46m accepts up to four 5m; and 12m accepts up to four 3m. A wait from two pairs has at most four tiles total because two copies of each are already used. Subtract any visible copies, then factor in the resulting shape, value, yaku, defense, turns remaining, and score situation.