How to Finish on a Double in Darts: The Double-Out Rule and Best Doubles to Leave

Guide · Keltek AI · Last reviewed June 2026

You have learned to score. You are stacking 60s and the odd 100, and your remaining number is dropping fast. Then it stalls. You arrive at the finish and keep missing, or worse, you throw a dart that wipes the turn out completely and hands your opponent the leg. That gap between scoring and closing is the single biggest thing separating a player who can throw from a player who can win. This guide is about closing it.

The double-out rule, exactly

In X01 darts (501, 301, 701 and so on) you count down from your starting score and the leg is won by the first player to reach exactly zero. The catch is how you are allowed to get there. The Darts Regulation Authority, whose rule book governs PDC events, puts it plainly: the winner is the first player to reduce the required score to exactly zero "by obtaining the required double." The World Darts Federation uses the same double-out standard across its tournaments.

A "double" is any number in the thin ring around the outer edge of the board: double 20 (D20) is worth 40, double 16 (D16) is worth 32, and so on. The 50 bull (the small red centre) counts as a double for finishing purposes, so it can also close a leg. The single bull, the green ring worth 25, does not count as a double and cannot finish.

So if you have 40 left, you finish on D20. If you have 32 left, you finish on D16. If you have 50 left, you can hit the bull. The last dart of the leg is always a double, never a single or a treble.

What "busting" is, and how to never do it again

A bust is the rule that punishes greedy or careless finishing. You bust if a dart in your turn:

• takes your remaining score below zero (you throw too much),
• leaves you on exactly 1 (because 1 cannot be finished, the smallest double is D1, worth 2), or
• reaches zero but not on a double (for example hitting a single 8 to go out from 8).

When you bust, the entire turn is wiped. Your score reverts to what it was at the start of that turn, any darts already thrown that turn are cancelled, and your opponent throws. Bust on the first dart of a turn at 80 and you are still on 80 next time, having gained nothing.

The practical rule that flows from this: always leave yourself an even number you can finish, and never leave 1. If you are on 18 and accidentally throw a single 17, you are left on 1 and the turn busts. If you had instead thrown a single 2 to leave 16, you would be sitting on a clean D8. Thinking about the number you leave behind matters as much as the number you score.

Why pros leave themselves on D16 or D20

Strong players do not just aim at whatever double is left. They steer their setup, sometimes two or three darts ahead, toward a double they trust. The two favourites are D16 and D20, and the reasons are different.

D16: the most forgiving double on the board

D16 (a score of 32) is the connoisseur's choice because of what happens when you miss. If your dart drops out of the double bed and into the single 16, you are left on 16, which is still an even number. From 16 you go for D8. Miss that into single 8 and you are on 8, going for D4. Miss again and you are on 4, going for D2. Every single miss leaves you on another double. That is the "powers of two" ladder: 32 -> 16 -> 8 -> 4 -> 2. You never get stranded on an odd number, so you are never forced to waste a dart splitting.

D20: the comfort of the top of the board

D20 (a score of 40) is popular for a simpler reason: it sits at the top of the board, the spot most players aim at all match long, so the throw feels natural and the grouping is usually tightest there. The downside is the miss. Drop into single 20 and you are left on 20 (D10). Worse, the segments either side of 20 are 1 and 5, so a wide dart out of the double can leave you on an awkward odd remainder. Many players still prefer D20 because confidence on the double you practise most beats theory.

The wider lesson is not "always leave D16" or "always leave D20." It is: leave a double you actually practise, and prefer an even one whose miss keeps you on a double. Other comfortable evens include D8 (16), D10 (20) and D12 (24).

Think one dart ahead: set up your finish

The skill that ties this together is planning the score you leave. Say you have 98 left with three darts. You could chase a single-dart-saving route, but the comfortable play is T20 (60) to leave 38, then D19 (or single 18 to leave 20 for D10). A cleaner example: on 64, throw T16 (48) to leave D8, or T14 (42) to leave 22 (D11). On 40 you simply throw D20. The good habit is to ask, before the dart leaves your hand, "if this lands where I want, what double do I have next?"

A few reliable setups worth memorising:

170 is the highest possible three-dart checkout. Anything above it cannot be closed in a single turn, so from 171 and up your job is to score and leave a clean two-dart or three-dart finish for next time. For the complete list, see the full darts checkout chart from 2 to 170.

How the app turns "leave a good double" into a number on screen

The advice above is sound until you are at the oche doing arithmetic under pressure. That is the exact moment most finishes are missed: not because the double was hard, but because the player picked the wrong route or left themselves on an odd number. Darts Scorekeeper closes that gap. After every turn the app reads your remaining score and suggests a checkout route that always ends on a double, and where several routes exist it leans toward the comfortable one, so "leave a good double" stops being abstract and becomes a concrete combination you can read off the screen.

Because the suggested route always ends on a double, you are never handed a finish you could not legally throw, and the app recalculates live if you score but do not check out. Its Checkout Trainer drills random finishes from 41 to 170 so that closing legs becomes muscle memory rather than mental maths. The double you practise on the wall is the double you will trust in a match.

Get Darts Scorekeeper on the App Store

iPhone · iOS 17+ · Free to download

Frequently asked questions

Do you have to finish on a double in darts?

In standard double-out X01 (501, 301, 701), yes. Your final dart must land in a double, or in the 50 bull, to reach exactly zero and win the leg. This is the rule used by the PDC and the WDF. Some casual "straight-out" formats let you finish on any segment, but tournament and league play is almost always double-out.

What does busting mean in darts?

You bust when a dart takes your remaining score below zero, lands you on exactly 1, or reaches zero without ending on a double. The whole turn is voided: your score reverts to what it was at the start of the turn and the next player throws. This is why you always leave an even number a double can finish, and never leave 1.

What are the best doubles to leave in darts?

D16 and D20 are the two most popular. D16 is prized because a miss into single 16 leaves 16, an even number that splits cleanly to D8, D4 then D2, keeping you on a double every time. D20 sits at the top of the board where many players aim most accurately, though a miss out of the bed can leave an awkward remainder.

Why do pros leave D16 instead of D20?

Because D16 is the most forgiving double on the board. Missing into the single leaves 16, which halves to 8, then 4, then 2, so you stay on an even number with a double on every follow-up dart. That "powers of two" route is why many professionals steer their setup toward 32 (D16).

What is the highest checkout in darts?

170, thrown as T20, T20, then the 50 bull. The bull counts as a double for finishing, so it legally closes the leg. Any score above 170 cannot be checked out in a single turn of three darts.

Keep reading

Sources: Professional Darts Corporation (PDC), World Darts Federation (WDF), and the Darts Regulation Authority (DRA) rule book, which governs PDC tournament play.