Darts 501 Score Calculator

What this calculator does

Keep score for a game of 501 (or 301, or 701) and see who wins, with averages and finishing tips. Most darts matches are x01 legs (single games). Each player starts on 501 and races to bring the score down to exactly zero. The rules that trip people up come at the end. The last dart has to land in a double, the thin outer ring worth twice the number. And a visit (one turn of three darts) that goes past zero, or leaves 1, is a bust that doesn't count at all.

This scorer works like a chalkboard. Type each visit as the darts thrown, such as T20 T20 S5, or just the total, such as 100. It keeps the score left and applies the bust rule. It finds the winner of a two-player leg and works out the 3-dart and first-9 averages. When the next thrower is close enough to finish, it suggests a checkout (a way to finish). It also warns about bogey numbers, the scores that can't be finished in one visit.

Where it's used

Why this math matters outside the classroom:

• Pub league chalking. A chalker takes a visit of 85 off 501 to write 416 on the board, then 140 off that to leave 276.
• Spotting a bust. A player on 32 who throws S20 then D8 would go to −4, so the visit is a bust and the board stays on 32.
• Tracking an average. A player who checks out 501 in 17 darts works out 501 ÷ 17 × 3 to get a 3-dart average of 88.41.
• Classroom subtraction. Teachers run a 301 game in class so pupils subtract two- and three-digit visit totals, such as 301 − 85 = 216.
• Practice targets. A club player compares first-9 averages week to week, such as 108.33 from opening visits of 100, 85 and 140.

Grade level and standards: Grade 3; Common Core State Standards for Mathematics 3.NBT.A.2. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

1. Pick the game (501, 301, 701 or a custom start), the finishing rule, and whether double-in applies.
2. Choose one or two players. In a two-player leg, player 1 throws first and visits alternate.
3. Type each player's visits in order, separated by commas. Use darts such as T20 S20 S5 or D16, or a visit total such as 100.
4. Read the result, the score left and the averages. Below them are the visit-by-visit sheet and the suggested checkout for whoever throws next.

What the inputs mean

Finish

Double-out is the standard rule in professional and league darts. Master-out also lets a treble finish. Straight-out lets any dart finish and only busts below zero. It's common for beginners.

Double-in (scoring starts with a double)

With double-in, a player's darts score nothing until they hit a double or the bullseye. The dart that hits the double counts. Some 301 leagues use it.

Player 1 visits

Write each dart as S (single), D (double) or T (treble, worth three times) plus a number from 1 to 20: S20, D16, T19. A plain number is a single. 25 or SB is the outer bull, and 50, DB or BULL is the bullseye. 0, M or MISS is a miss. A visit written as one number on its own (like 100 or 60) is read as that visit's total.

Player names

Optional labels for the results, such as Jo, Sam. They never change the scores.

Formula and method

score left = starting score − sum of the visits that counted
bust (double-out): the visit would go below 0, leave 1, or reach 0 without a double or the bullseye; the visit scores 0
darts thrown = 3 per visit, except the checkout visit, which counts only the darts up to the finish
3-dart average = points scored ÷ darts thrown × 3
first-9 average = points in the first three visits ÷ 9 × 3

Each dart is taken off the score in turn. Under the double-out rule, the leg can only end on a double, and the bullseye counts as double 25. A dart might take the score below zero, leave exactly 1 (which no double can finish), or reach zero on a single or treble. Then the whole visit is a bust. The score goes back to what it was before the visit, and the rest of that visit's darts aren't thrown.

Totals are handy when you only write down what each visit scored. The scorer can still spot a total that goes below zero or leaves 1. But it can't see which dart finished a leg, so a checkout typed as a total is accepted and flagged. Type the darts of the last visit, such as T13 D16, to have the double checked.

Averages follow the usual custom. Every visit counts as three darts, including busts and visits where darts missed. The winning visit counts only the darts actually needed. The first-9 average looks only at the first three visits (nine darts), when players are scoring heavily and haven't started aiming at doubles yet.

Worked example

An invented two-player 501 leg. Rosa Kettering scores 100, 85, 140, 60 and 45, then throws T13 D16. Milo Tanaka-Price, throwing second, scores 81, 60, 100, 41 and 26.

1. Rosa: 100 + 85 + 140 + 60 + 45 = 430, which leaves 501 − 430 = 71.
2. Her sixth visit, treble 13 (39) and double 16 (32), makes exactly 71 and ends on a double. So she checks out (finishes) with her second dart.
3. Rosa threw 5 × 3 + 2 = 17 darts, so her 3-dart average is 501 ÷ 17 × 3 = 88.41. Her first-9 average is (100 + 85 + 140) ÷ 9 × 3 = 108.33.
4. Milo: 81 + 60 + 100 + 41 + 26 = 308, leaving 193 after 15 darts, an average of 61.60.

Result: Rosa wins the leg with a 71 checkout. Milo was left on 193.

Understanding the result

The score left is what a chalker (the person keeping score) would write on the board after each visit. A bust leaves it unchanged. That's why busts show 0 scored in the sheet.

The 3-dart average is the standard way to compare scoring across legs and players, because it doesn't depend on how long a leg lasted. The first-9 average is usually higher than the full average, because the darts aimed at finishing pull the full figure down.

When the next thrower has 170 or less and a finish exists, the suggested checkout uses the same routes as the darts checkout calculator. A bogey-number warning means there's no three-dart double-out finish from that score. So the next visit should set up a finish instead.

Assumptions and limitations

• Standard board values: singles 1–20, doubles and trebles of those, the outer bull 25 and the bullseye 50 (a double).
• In a two-player leg, player 1 throws first and the players alternate visits. The first player to reach exactly zero wins.
• A visit with fewer than three darts typed (other than a checkout) counts as three darts. The missing darts are treated as misses.
• It scores one leg at a time. Sets and legs of a whole match aren't tracked.
• Checkouts entered as totals can't be checked for the finishing double.
• The suggested route is for double-out. Under master-out, a treble finish may be shorter.
• Text is limited to 200 characters per player, enough for a typical leg written as totals.

Frequently asked questions

Sources

• WDF Playing and Tournament Rules, 20th revised edition, rules 2.01–2.05 and 2.09 (World Darts Federation) (checked 2026-10-19)

How this calculator is checked

Method: World Darts Federation Playing and Tournament Rules (20th revised edition): straight start, double finish with the bull counting as double 25, the bust rule, first to finish wins. Double-in, master-out and straight-out are common format options. Averages per the standard 3-dart convention. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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