Master 501

Master 501 is an advanced variant of standard 501 in which players must reduce their score from exactly 501 to exactly zero, with two additional constraints: no scoring begins until a player "masters in" by hitting a double, treble, or bullseye, and the final dart must also land in a double, treble, or bullseye to "master out." The combined master-in and master-out requirements make this format significantly more demanding than the conventional double-in/double-out game.

Each player begins with a score of 501. A standard bristle dartboard and a set of three darts per player are required. The scoreboard should display 501 beside each player's name, along with a clear notation that the format is Master In / Master Out so all participants and any scorer or adjudicator are aware of the entry and exit conditions.

Throwing order is determined in the usual manner — each player throws a single dart at the bullseye, and the player whose dart lands closest to the inner bull throws first. In the event of a tie (e.g., both darts in the outer bull), those players re-throw.

Before play commences, confirm with all players that the Master In rule is in effect (first scoring dart must be a double, treble, or bullseye) and that the Master Out rule is in effect (final dart must be a double, treble, or bullseye). Two or more players may compete.

Players take turns throwing three darts per visit. The fundamental turn-by-turn mechanics follow standard 501, with the critical additions of the master-in and master-out requirements described below.

Master In: No darts count toward reducing a player's score until that player has landed a dart in a double segment, a treble segment, or the bullseye (outer or inner). Any darts that land in a single segment before a player has mastered in are void and do not score. Once a qualifying dart is thrown, the player is "in," and that dart and any remaining darts in the visit score normally.

• For example, if your first dart lands in single 20 (void — you are not yet in), your second dart lands in treble 19 (57 — you are now in), and your third dart lands in single 18 (18), your total deduction for the visit is 75 (57 + 18), bringing your score from 501 to 426.
• If all three darts land in single segments, your score remains at 501 and you have not mastered in.

Scoring after mastering in: Once a player has mastered in, all subsequent darts in that visit and in all future visits score at their standard values:

• Single segment = face value (1–20)
• Double ring (outer narrow band) = 2× face value
• Treble ring (inner narrow band) = 3× face value
• Outer bullseye = 25
• Inner bullseye = 50

Master Out: To finish, the final dart of the game must land in a double, treble, or the bullseye. This is the key distinction from standard double-out 501 — trebles are also valid finishing darts. For instance, if a player has 57 remaining, treble 19 is a legitimate one-dart checkout. Similarly, a remaining score of 60 can be finished with treble 20.

Bust rule: A player's turn is void — and the score reverts to what it was at the start of that visit — if any of the following occur:

• The player's remaining score goes below zero.
• The player's remaining score reaches exactly 1 (since no double, treble, or bullseye equals 1).
• The player's remaining score reaches exactly zero, but the final dart did not land in a double, treble, or bullseye.

For example, if a player has 40 remaining and throws single 20 (leaving 20), then single 20 again (leaving 0), this is a bust because the final dart was a single, not a double, treble, or bullseye. The score reverts to 40. Had the player instead thrown double 20 on the first dart, the leg would be won.

Standard dartboard point values apply throughout the game:

• Single: 1–20 points (face value of the segment)
• Double: 2–40 points (2× the segment number)
• Treble: 3–60 points (3× the segment number)
• Outer bullseye: 25 points
• Inner bullseye: 50 points (counts as both a valid master-in and a valid master-out dart)

The maximum score per three-dart visit is 180 — three treble 20s. Note, however, that during the master-in visit, any singles thrown before the qualifying dart do not count. For instance, if your first two darts are single 20 and single 20 (both void because you have not mastered in), and your third dart is double 20 (40), your deduction for that visit is only 40, not 100.

Because trebles are valid finishing darts under master-out rules, the highest possible checkout is 180 (treble 20, treble 20, treble 20 — if the remaining score is exactly 180). This exceeds the highest standard double-out checkout of 170.

The first player to reduce their score to exactly zero wins the leg, provided the final dart lands in a double, treble, or bullseye. If a match format is used, players compete over multiple legs (e.g., best of 5 or best of 7 legs). In the event that throwing order alternates each leg, the player who did not throw first in the previous leg throws first in the next.

Standard bust rules govern all attempts at a finish: any visit that reduces the score below zero, to exactly 1, or to zero without a valid master-out dart is void, and the player's score returns to its value at the start of that visit.

Double In / Double Out: The most common tournament format for 501. Only doubles and the bullseye qualify for starting and finishing — trebles do not count as valid in or out darts. This is the standard in PDC, WDF, and most league competitions.

Master In / Open Out: A player must master in (double, treble, or bullseye) to begin scoring, but may finish on any segment — no special out dart is required. This eases the finishing phase while preserving the difficulty of getting started.

Open In / Master Out: Any dart scores from the first throw (no in requirement), but the final dart must be a double, treble, or bullseye. This variant focuses the additional challenge entirely on the checkout.

Alternate starting scores: The master-in/master-out format can be applied to any x01 game. Master 301 and Master 701 follow identical rules with starting scores of 301 and 701, respectively. The shorter 301 format intensifies the impact of the master-in requirement, as fewer total darts are thrown and a slow start is more costly.

Prioritize high-value master-in targets: When attempting to master in, aim for treble 20 (60) rather than a low double. If you hit it, you start with maximum deduction; if you miss into single 20, you are no worse off (the single simply does not count). Aiming at a low double like double 3 wastes scoring potential even when you hit it.

Expand your checkout knowledge beyond doubles: Under master-out rules, trebles open up finishing combinations that do not exist in standard double-out play. Treble 20 (60), treble 19 (57), treble 18 (54), treble 17 (51), and the inner bull (50) are all single-dart finishes at those scores. Familiarize yourself with these additional paths — they can save you entire visits.

Leave yourself flexible finishes: Because both doubles and trebles are valid out darts, try to leave scores that offer multiple checkout options. For example, leaving 40 gives you double 20 or — if you prefer a safety net — you can set up treble routes with your earlier darts. A score of 51 is now a single-dart finish (treble 17), whereas in standard double-out it would require two darts.

Don't waste darts chasing master-in on marginal targets: If your first dart misses the treble and lands in a single, reassess your second dart. Continuing to aim at treble 20 is generally correct because even a missed treble yields useful board position once you are in. Switching to a low-percentage bullseye attempt out of frustration often wastes the visit.

Practice treble finishing under pressure: Most players drill double finishes extensively but neglect treble checkouts. Dedicate practice time to hitting treble 17, treble 19, and treble 20 as finishing darts. The ability to check out on a treble when your remaining score is odd (e.g., 57 via treble 19) is a significant advantage unique to the master-out format.