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Killer Darts Calculator

Keep track of a game of killer darts: who is a killer, lives left, knockouts and the winner, with optional house rules for own doubles and trebles.

Level: Grade 1

  • Common Core standard 1.OA.C.6Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
Printable worksheet

Killer Darts Calculator

Inputs
Players
House rule: a killer hits their own double

One visit per comma, in turn order. Doubles do the work: D7 on your own number makes you a killer, then D on others' numbers takes lives. M = miss.

Separated by commas, in throwing order. Labels only; they never change the scores.

Result

Result

Player 1 wins with 1 life left

Player 1 wins with 1 life left. Player 1 (7): 1 life, killer; Player 2 (3): 0 lives; Player 3 (9): 0 lives.

Player 1: lives left
1
Player 2: lives left
0
Player 3: lives left
0
Killers
Player 1
Knocked out
Player 2 (Round 4, by Player 1); Player 3 (Round 3, by Player 2)
What happened
Round 1: Player 1 becomes a killer; Round 1: Player 2 becomes a killer; Round 1: Player 3 becomes a killer; Round 3: Player 2 knocks out Player 3; Round 4: Player 1 knocks out Player 2

See the step-by-step solution ↓

Lives table
Lives table
PlayerNumberLivesKiller?Status
Player 171YesWinner
Player 230YesOut: Round 4, by Player 1
Player 390YesOut: Round 3, by Player 2

Step-by-step solution

  1. Player 1 (number 7): starting lives, minus lives lost

    3−2=1

  2. Player 2 (number 3): starting lives, minus lives lost

    3−3=0

  3. Player 3 (number 9): starting lives, minus lives lost

    3−3=0

  4. Only Player 1 has lives left, so Player 1 wins

    result=Player 1 wins with 1 life left

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

What this calculator does

Keep score in a game of Killer darts and see who is still in, who is a killer and who wins. Killer is a darts party game built around doubles. Every player owns a number on the board. Hit the double of your own number and you become a killer. From then on, every double you hit on an opponent's number takes one of their lives. Lose all your lives and you are out. The last player standing wins.

Keeping track gets confusing quickly, especially with three or four players being knocked out in turn. Enter each player's number, the starting lives and each visit's darts (one turn of up to three throws). The calculator then follows the game in throwing order. It shows who is a killer, everyone's lives, who knocked out whom and in which round, and the winner. Two common house rules are options rather than fixed rules, because they vary from table to table.

Where it's used

Why this math matters outside the classroom:

  • Party nights. Four friends each pick a number and play killer with 3 lives, and the last one standing wins.
  • Doubles practice. Players use killer to practise doubles under pressure, since only doubles change the game.
  • Counting down lives. A player with 3 lives hit twice works out 3 − 2 = 1 life left.
  • Club socials. Darts clubs run killer at social nights because it suits mixed abilities and any number of players.

Grade level and standards: Grade 1; Common Core State Standards for Mathematics 1.OA.C.6. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

  1. Choose 2, 3 or 4 players, give each a different number from 1 to 20, and set the starting lives (3 is usual, 5 makes a longer game).
  2. Pick the house rules your group plays, if any: what happens when a killer hits their own double, and whether trebles take two lives.
  3. Type each player's visits in order, separated by commas. Only doubles (and trebles, with that rule) on players' numbers matter; type the other darts as they landed or as M.
  4. Read the result, the lives table and the list of what happened.

What the inputs mean

Player 1's number
Players often choose numbers by throwing a dart with their weaker hand. Any numbers work here as long as no two players share one.
House rule: a killer hits their own double
A house rule. Some groups let a killer win back a lost life by hitting their own double again; others punish it by taking a life. The default is that nothing happens.
House rule: a killer's treble takes 2 lives
A house rule. When on, a killer's treble on an opponent's number takes 2 lives instead of none.
Player 1 visits
Visits go round in order, and a knocked-out player stops throwing, so don't type visits for a player after they are out.
Player names
Separated by commas, in throwing order. Labels only; they never change the scores.

Formula and method

become a killer: hit the double of your own number
killer hits an opponent's double: that opponent loses 1 life (treble rule: a treble takes 2)
lives left = starting lives − lives lost (+ lives won back, with the restore rule)
out at 0 lives; the last player with lives wins

In your typed darts, S means a single, D a double, T a treble (triple) and M a miss, so D7 is the double 7.

Players throw in a fixed order, three darts a visit. Until you are a killer, only the double of your own number matters. Once you are, aim at the doubles of the other players' numbers. A player who isn't a killer can't take lives, even by hitting an opponent's double.

Each life lost is subtracted from the starting lives. With the restore house rule, a killer who hits their own double again gets one life back, but never more than they started with. With the cost-a-life rule, that dart takes one of their own lives instead, which can knock them out.

When a player reaches zero they are skipped for the rest of the game. As soon as only one player has lives left, the game is over, and any darts after that aren't thrown.

Worked example

Three invented players with 3 lives each: Juno Barraclough (number 7), Silas Achterberg (3) and Ines Okafor-Brandt (9). Juno throws D7 S7 M, D3 D3 M, D9 M S3, S3 D3. Silas throws D3 M S2, D7 S2 M, D9 D9 M. Ines throws S9 S12 D9, D7 M M.

  1. Round 1: each player hits their own double (D7, D3, D9) and becomes a killer.
  2. Round 2: Juno's D3 D3 takes two of Silas's lives, leaving 1. Silas and Ines each hit D7, so Juno drops to 3 − 2 = 1.
  3. Round 3: Juno's D9 takes Ines to 2, then Silas's D9 D9 takes her to 0: she is out.
  4. Round 4: Juno throws S3, then D3, which takes Silas's last life.

Result: Juno wins with 1 life left.

Understanding the result

The lives table shows the state of the game at a glance. A player with plenty of lives but no killer status can still lose lives to any killer, but can't take lives from anyone else. That is why becoming a killer early matters.

In a game in progress, the result says how many players are left, each player's lives in throwing order, and who throws next.

Assumptions and limitations

  • Each player has a different number from 1 to 20; the bull isn't used.
  • Players throw one visit of up to three darts each per round, in the order listed, skipping anyone who is out.
  • Lives can't go below zero; a treble on a player with 1 life left takes just that life.
  • Killer has many local versions. Some need three hits on your number to become a killer, some let killers lose their status, and some count only the bullseye as a kill. Only the two listed house rules are offered here.
  • Up to four players.

Frequently asked questions

How do you become a killer in darts?

In the standard game, by hitting the double of your own number. Until then, you can't take lives from anyone. Some groups make it harder by requiring three hits on your number.

What happens if a killer hits their own double?

It depends on your house rules. Common choices are that nothing happens, that you win back a lost life, or that you lose a life. Agree before you start; this calculator lets you pick.

How many lives do you start with in killer?

Three is the usual number. Five lives makes a longer game that suits bigger groups. Everyone should start with the same number.

Sources

How this calculator is checked

Method: Published house rules for killer darts (DolfDarts): own double makes you a killer, killers take a life per double on an opponent's number, last player with lives wins. Own-double and treble rules are labelled house-rule options; no governing body publishes an official version. 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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