Darts · Rules explained
Double out vs straight out in darts
Double out means the dart that takes your score to exactly 0 must land in a double or the bullseye; straight out means any dart that reaches exactly 0 wins. Double out is the rule for 501 at WDF and PDC events, and it is the harder of the two: leaving 1 is a bust, and more scores have no one-visit finish.
What changes between double out and straight out?
Only the finish. Start scores, visits of three darts and legs work the same way under both rules; the scoring guide covers them. Here is what the finishing rule changes:
| Double out | Straight out | |
|---|---|---|
| The winning dart | A double or the bullseye | Any dart |
| A visit is a bust if you | Score more than you have left, leave 1, or reach 0 without a double | Score more than you have left |
| Left on 1 | Not allowed: no double is worth 1 | Fine: a single 1 wins |
| Highest one-visit finish | 170 | 180 |
| Scores up to 180 with no one-visit finish | The seven bogey numbers and everything from 171 to 180 | Only the nine totals three darts cannot make |
| Where it is played | The standard for 501, including WDF and PDC events | A house rule, mostly in casual games |
What is straight out in darts?
Straight out, sometimes called single out or open out, lets any dart finish the leg. A single, a treble, the outer bull and the bullseye all count, as long as the score lands on exactly 0. The only bust left is scoring more than you need.
It makes legs shorter and friendlier for beginners, because there is no double to hit at the end. It also changes finishing strategy. Under double out you plan a route to a double; under straight out you just need the right total, so many finishes take fewer darts.
The same scores under each rule
These are the same eleven scores checked out both ways, with the finish the app suggests under each rule:
| Left | Finish the app suggests | Darts | Note |
|---|---|---|---|
| 1 | No finish in one visit | – | Leaving 1 is a bust |
| 3 | 1 · D1 | 2 | An odd score needs a single first |
| 25 | 1 · D12 | 2 | The outer bull is not a double |
| 50 | 18 · D16 | 2 | The bullseye also finishes it |
| 61 | 11 · Bull | 2 | The bullseye is the double here |
| 99 | T20 · 7 · D16 | 3 | Three darts |
| 121 | T20 · 11 · Bull | 3 | Three darts |
| 162 | No finish in one visit | – | A bogey number |
| 169 | No finish in one visit | – | A bogey number |
| 171 | No finish in one visit | – | Above 170 nothing finishes |
| 180 | No finish in one visit | – | A maximum scores 180 but cannot finish |
Routes computed by the same checkout rules the app uses.
| Left | Finish the app suggests | Darts | Note |
|---|---|---|---|
| 1 | 1 | 1 | A single 1 wins |
| 3 | 3 | 1 | One dart instead of two |
| 25 | 25 | 1 | The outer bull finishes it |
| 50 | Bull | 1 | The bullseye, first choice now |
| 61 | T20 · 1 | 2 | The last dart can be a single |
| 99 | T20 · T13 | 2 | Two darts instead of three |
| 121 | T20 · T20 · 1 | 3 | Still three darts |
| 162 | T20 · T20 · T14 | 3 | A finish without a double |
| 169 | No finish in one visit | – | No three darts total 169 |
| 171 | T20 · T20 · T17 | 3 | Scores above 170 can finish |
| 180 | T20 · T20 · T20 | 3 | A maximum wins the leg |
Routes computed by the same checkout rules the app uses.
Straight out turns the totals from 171 to 180 that three darts can make into finishes, and the bogey numbers 159, 162, 165 and 168 too. 163, 166 and 169 have no one-visit finish under either rule, because no three darts add up to them.
Leaving 1: a leg played straight out
This leg is played straight out. On visit 7, Alex is on 41 and scores 40, leaving 1. Under double out that visit would be a bust and Alex would stay on 41. Under straight out it stands, and a single 1 wins the leg next time.
| Visit | Player | Scored | Left (Alex · Sam) | What happened |
|---|---|---|---|---|
| 1 | Alex | 140 | 361 · 501 | |
| 2 | Sam | 100 | 361 · 401 | |
| 3 | Alex | 180 | 181 · 401 | |
| 4 | Sam | 60 | 181 · 341 | |
| 5 | Alex | 140 | 41 · 341 | On a finish: T13 · 2 |
| 6 | Sam | 100 | 41 · 241 | |
| 7 | Alex | 40 | 1 · 241 | On a finish: 1. Under double out this visit would be a bust, leaving Alex on 41 |
| 8 | Sam | 140 | 1 · 101 | On a finish: T17 · Bull |
| 9 | Alex | 1 | 0 · 101 | Checkout: leg won. A single 1 wins the leg |
Scored visit by visit by the same straight-out rules the app uses.
What is double in, double out?
Double in is a starting rule, separate from the finish. A double is needed to start scoring: darts thrown before your first double score nothing, and the double itself is your first score. Standard 501 is straight in, where every dart counts from the start. Put together, the start and finish rules give these common formats:
| Format | To start scoring | To finish |
|---|---|---|
| Straight in, double out (standard 501) | Any dart | A double or the bullseye |
| Double in, double out | A double or the bullseye | A double or the bullseye |
| Straight in, straight out | Any dart | Any dart |
| Straight in, master out | Any dart | A double, a treble or the bullseye |
The PDC World Grand Prix is played double in, double out: every leg of 501 has to start and finish on a double. Double in is also a traditional way to play 301; see 301 vs 501.
How the app handles it
The app has two checkout rules: Double out, the default, and Straight out, where any visit that reaches exactly 0 wins and only going below 0 is a bust. Under double out, a visit that would leave 1 is a bust too. The app records one total per visit, not single darts, so it cannot see which dart finished the leg: under double out it trusts that the last dart was a double. Double in, master in and master out are not supported.
Questions
Is straight out easier than double out?
Yes. Any dart can finish, the only bust is going below 0, and many finishes take fewer darts: 99 is two darts straight out (T20, T13) but three under double out (T20, 7, double 16).
Can you finish a leg on the outer bull?
Only under straight out. The outer bull is worth 25 but is not a double, so under double out a score of 25 is finished another way, for example a single 1 and then double 12.
What is master out in darts?
A finishing rule between the two: the last dart can be a double or a treble, and the bullseye counts as a double. Odd scores such as 3, 9 or 57 can then go out with one treble, but a single still cannot finish, so a score of 1 can never be checked out.
Last reviewed September 25, 2026
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