Darts scoreboard

How to use the darts scoreboard

1. Open Game settings, pick 301, 501 or 701, the number of players (one player is handy for practice) and type the names. Leave Double-out on for standard rules.
2. Choose the match length. "Legs: first to 3" is a best-of-five match. For a set format, choose for example sets first to 3 with legs first to 3, as in televised events.
3. Press Start new game. The highlighted player is the one at the oche.
4. After each visit (three darts), add up the darts and enter the total on the keypad, or tap one of the common scores such as 60, 100 or 140. On a laptop you can type the number and press Enter.
5. When a visit takes a player to exactly zero, the scoreboard asks whether the last dart was a double and how many darts were used. Answer and the leg is scored.
6. Made a typo? Undo last visit steps back one visit at a time, even across the end of a leg.

The rules this scorer follows

Each player starts on the same score and subtracts what they hit in each visit of three darts. The first player to reach exactly zero wins the leg. With double-out, the dart that reaches zero must land in the outer double ring or the bullseye (the bull counts as double 25 = 50).

A visit is a bust when it would take you below zero, leave you on 1 (you cannot finish 1 with a double), or reach zero with a dart that is not a double. On a bust the score returns to what it was at the start of the visit and your turn ends.

The highest possible visit is 180 (three treble 20s). Some totals below that cannot be made with three darts at all: 163, 166, 169, 172, 173, 175, 176, 178 and 179. The scoreboard rejects these as typing errors instead of quietly accepting them.

Checkouts and bogey numbers

When a player has 170 or less, the card shows a recommended checkout. The tool always picks a route with the fewest darts, then prefers the targets most players aim at: treble 20 and treble 19 for scoring, and double 20, double 16 or double 8 to finish, because a miss on those often leaves another double. Many routes are possible for most scores, so see the suggestion as a sensible default, not the only answer.

Seven scores of 170 or less cannot be finished in three darts with double-out: 169, 168, 166, 165, 163, 162 and 159. Darts players call these bogey numbers. If you are on one, the card says "no checkout": score enough to leave a finish for your next visit, ideally an even number such as 40 or 32.

Worked example: a 501 leg

Anna and Ben play 501, double-out. Anna scores 100, 140 and 100, leaving 161. The card suggests T20 T17 Bull. She hits 81 and has 80 left; the card now shows T20 D10. Meanwhile Ben has 32 left and throws 33 – the scoreboard tells him it is a bust and keeps him on 32. On her next visit Anna hits treble 20 with her first dart and double 10 with her second. She enters 80, confirms "finished on a double" and picks 2 darts. Anna threw 4 full visits plus 2 darts = 14 darts for 501 points, so her 3-dart average for the leg is 501 ÷ 14 × 3 = 107.4.

Tips for scoring a match

• Let the thrower call it. In most leagues the player says their score before pulling the darts; the scorer enters it. Use Undo straight away if it was wrong.
• Practise checkouts solo. Pick one player and 101 or 121 and play leg after leg against your average.
• Busts still count as darts. A bust visit adds three darts and no points, which is why busting hurts the average as well as the leg.
• For Cricket instead of X01, use our cricket darts scoreboard.

How we tested it

We wrote automated tests for the scoring code and ran them with Node. A brute-force check of every combination of three darts confirmed that exactly 163, 166, 169, 172, 173, 175, 176, 178 and 179 are impossible, and the scorer accepts every other total from 0 to 180. For every score from 2 to 170 the suggested checkout was checked to add up to the score, end on a double and use no more than three darts; it returned T20 T20 Bull for 170, T20 D20 for 100 and D1 for 2, and no checkout for all seven bogey numbers. Bust tests covered going below zero, leaving 1, and reaching zero without a double. Match tests played full 301 and 101 legs and checked that the thrower rotates each leg, that legs and sets are won at the right moment, and that the 3-dart average equals points ÷ darts × 3.