Darts checkout chart and calculator

How to use the calculator

Type the score you have left and pick the finish rule. The big line is the route the app suggests for that score, with the number of darts it takes. Under it, the calculator lists up to five other finishes, found by trying every combination of one, two and three darts. Set Darts in hand to 2 or 1 when you have already thrown part of your visit: you then see only the finishes that fit, or a setup shot for your next visit, leaving a double when one is in reach.

How to read a route: T is a treble (three times the number), D is a double (twice the number), 25 is the outer bull and Bull is the inner bull, worth 50. A plain number is a single. So T20, 11, Bull means treble 20, single 11, then the bullseye: 60 + 11 + 50 = 121.

The rules a checkout has to follow

• Double out. The dart that takes you to exactly 0 must land in the double ring or the inner bull. The inner bull counts as double 25 for finishing; the outer bull, worth 25, does not.
• Bust. Going below 0, leaving 1 or reaching 0 without a double wipes out the whole visit, and the turn passes. Nobody can be left on 1, because no double is worth 1. Checkouts 2 to 40 shows how busts happen at the end of a leg.
• Three darts a visit. The most one visit can check out is 170: two treble 20s and the Bull.

The full checkout chart, 2 to 170

Every double-out score, with the finish the app suggests and the darts it takes. The chart runs a line-for-line copy of the app's route code, so it shows the same finish as the scoreboard.

Of the 169 scores from 2 to 170, 21 go out with one dart (the 20 doubles and the Bull), 81 need two darts at best, 60 need all three, and 7 cannot be finished in one visit.

How the chart picks a route

Most scores can be finished in many ways; 68 alone has hundreds of dart combinations. The chart picks one with four rules, the same rules the app uses:

1. One dart if you can. An even score up to 40 is its own double: 32 is D16 and 40 is D20. The exception is 50: the Bull finishes it, but the chart plays 18, D16 and keeps the Bull as the last resort.
2. Otherwise a single, then a double. The single bed is the biggest target on the board, so the first choice is a single that leaves a good double: 41 is 9, D16 and 60 is 20, D20. From 61 to 70 a single cannot leave a double in the ring, so it sets up the Bull instead: 70 is 20, Bull.
3. Then a treble, then a double, for 71 to 98 and for 100: 81 is T15, D18 and 100 is T20, D20. 101, 104, 107 and 110 go out with a treble and the Bull.
4. Then three darts, starting with T20 and followed by the best two-dart finish for what is left: 121 is T20, 11, Bull and 170 is T20, T20, Bull.

When more than one double is within reach, the chart takes them in a fixed order: D16 (32) first, then D20 (40), D18 (36) and D12 (24), then D8, D4, D10, D6, D14 and D2, the other doubles after that, and the Bull last.

D16 comes first because it halves cleanly: miss it into the single 16 and you are on 16, another double. Checkouts from 2 to 40 follows the chain all the way down.

How the calculator ranks the other routes

The alternatives come from brute force: every one, two and three dart combination that reaches exactly 0 with the last dart on a double or the Bull. They are ranked by the fewest darts, then the fewest hard setup darts (a treble, a double or either bull is harder to hit than a plain single), then the fewest setup darts on a double or the Bull (a miss just outside the double ring scores nothing), then the double they finish on, in the order above. The calculator takes the best route on each double first, so the list covers several doubles, with one more route on the double the app uses. It never repeats the route the app suggests, and stops at five. With darts in hand set to 2 or 1, longer routes drop out.

Bogey numbers: 159, 162, 163, 165, 166, 168 and 169

Seven scores of 170 or less have no one-visit finish, so the chart has no route for them: 159, 162, 163, 165, 166, 168, 169. In short, above 160 only the Bull is big enough to finish, and the first two darts can leave it only from 161, 164, 167 and 170. 159 falls in the gap: two darts cannot make 109 for the Bull or 119 for D20. Bogey numbers explained goes through the reasoning.

On a bogey number, use the visit to leave a double. The calculator suggests a setup: on 169 it is T20, T20, 17, leaving 32 for D16 next time. Checkouts 131 to 170 lists the setup for each one.

Straight out: what changes

Straight out changes one rule. Any dart that reaches exactly 0 wins, whatever bed it lands in. Singles and trebles can finish, you can go out on 1, and the only bust is scoring more than you need. The highest checkout becomes 180 (three treble 20s), four of the seven bogey numbers (159, 162, 165 and 168) become finishes, and the only scores up to 180 that one visit cannot finish are the nine totals three darts cannot make: 163, 166, 169, 172, 173, 175, 176, 178, 179.

Switch the calculator to Straight out to check any score from 1 to 180. When a score cannot be finished, its setup never leaves 1: only a single 1 would finish that, and every other bed busts. The full comparison is in double out vs straight out.

Checkout tables by range

• Checkouts 2 to 40: one dart at a double, what to do on an odd number, and the D16 halving chain.
• Checkouts 41 to 60: a single, then a double, and where a missed single leaves you.
• Checkouts 61 to 100: a treble, then a double, 100 as T20, D20, and when to go for the Bull.
• Checkouts 101 to 130: three-dart finishes and setup shots.
• Checkouts 131 to 170: 170, 167, 164 and 161, and the bogey numbers.