Home page.

Below are shown 5-pin and 20-pin variants in parallel columns with the 10-pin and 15-pin versions of the home page.

Half bowling The traditional ten-pin game Bowling-and-a-half Double bowling
Pins and lane.

5 pins are arranged in a vee, at a center-to-center distance of 12 inches, their positions numbered for reference.

The lane, 29½ inches wide, would be constructed of 27 boards each slightly more than one inch wide. The length of the lane is as desired.

10 pins are arranged in a triangle, at a center-to-center distance of 12 inches, their positions numbered for reference.

The lane, 41½ inches wide, is traditionally constructed of 39 boards each slightly more than one inch wide. The length of the lane is 60 feet from foul line to the center of the number-1 pin.

15 pins are arranged in a triangle, at a center-to-center distance of 12 inches, their positions numbered for reference.

The lane, 53½ inches wide, would be constructed of 51 boards each slightly more than one inch wide. The length of the lane is as desired.

20 pins are arranged in a triangle with one gap, at a center-to-center distance of 12 inches, their positions numbered for reference.

The lane, 65½ inches wide, would be constructed of 63 boards each slightly more than one inch wide. The length of the lane is as desired.

Length of game.
5 frames 10 frames 15 frames 20 frames
All frames except the last.
In each of the 1st through 4th frames, a bowler is presented a full rack of 5 pins, and rolls the ball 1 time. In each of the 1st through 9th frames, a bowler is presented a full rack of 10 pins, and rolls the ball 1 or 2 times. In each of the 1st through 14th frames, a bowler is presented a full rack of 15 pins, and rolls the ball 1, 2, or 3 times. In each of the 1st through 19th frames, a bowler is presented a full rack of 20 pins, and rolls the ball 1, 2, 3, or 4 times.
A spare is recorded when all pins are felled on the first roll.
  • The frame ends.
  • Earned are 5 points plus a bonus equal to the pinfall of the next roll, which will occur in the next frame.
A strike is recorded when all pins are felled on the first roll.
  • The frame ends.
  • Earned are 10 points plus a bonus equal to the combined pinfall of the next 2 rolls, which will occur in the next 1 or 2 frames.
A star is recorded when all pins are felled on the first roll.
  • The frame ends.
  • Earned are 15 points plus a bonus equal to the combined pinfall of the next 3 rolls, which will occur in the next 1, 2, or 3 frames.
A diamond is recorded when all pins are felled on the first roll.
  • The frame ends.
  • Earned are 20 points plus a bonus equal to the combined pinfall of the next 4 rolls, which will occur in the next 1, 2, 3, or 4 frames.
An open frame is recorded when at least 1 pin was standing after the roll.
  • The frame ends.
  • Earned is 1 point for each pin felled, with no bonus.
A spare is recorded when at least 1 pin was standing after the 1st roll, but all remaining pins were felled on the 2nd roll.
  • The frame ends.
  • Earned are 10 points plus a bonus equal to the pinfall of the next roll, which will occur in the next frame.
A strike is recorded when at least 1 pin was standing after the 1st roll, but all remaining pins were felled on the 2nd roll.
  • The frame ends.
  • Earned are 15 points plus a bonus equal to the pinfall of the next 2 rolls, which will occur in the next 1 or 2 frames.
A star is recorded when at least 1 pin was standing after the 1st roll, but all remaining pins were felled on the 2nd roll.
  • The frame ends.
  • Earned are 20 points plus a bonus equal to the pinfall of the next 3 rolls, which will occur in the next 1, 2 or 3 frames.
  An open frame is recorded when at least 1 pin was standing after the 2 rolls.
  • The frame ends.
  • Earned is 1 point for each pin felled, with no bonus.
A spare is recorded when at least 1 pin was standing after the 1st and 2nd rolls, but all remaining pins were felled on the 3nd roll.
  • The frame ends.
  • Earned are 15 points plus a bonus equal to the pinfall of the next roll, which will occur in the next frame.
A strike is recorded when at least 1 pin was standing after the 1st and 2nd rolls, but all remaining pins were felled on the 3nd roll.
  • The frame ends.
  • Earned are 20 points plus a bonus equal to the pinfall of the next 2 rolls, which will occur in the next 1 or 2 frames.
    An open frame is recorded when at least 1 pin was standing after the 3 rolls.
  • The frame ends.
  • Earned is 1 point for each pin felled, with no bonus.
A spare is recorded when at least 1 pin was standing after the 1st, 2nd, and 3rd rolls, but all remaining pins were felled on the 4nd roll.
  • The frame ends.
  • Earned are 20 points plus a bonus equal to the pinfall of the next roll, which will occur in the next frame.
      An open frame is recorded when at least 1 pin was standing after the 4 rolls.
  • The frame ends.
  • Earned is 1 point for each pin felled, with no bonus.
Marks.
A spare is a mark. A strike or spare is a mark.
  • If no pins are felled on the 1st roll, but all 10 on the 2nd roll, it counts as only a spare.
A star, strike, or spare is a mark.
  • If no pins are felled on the 1st roll, but all 15 on the 2nd roll, it counts as only a strike.
  • If no pins are felled on the 1st and 2nd rolls, but all 15 on the 3rd roll, it counts as only a spare.
A diamond, star, strike, or spare is a mark.
  • If no pins are felled on the 1st roll, but all 20 on the 2nd roll, it counts as only a star.
  • If no pins are felled on the 1st and 2nd rolls, but all 20 on the 3rd roll, it counts as only a strike.
  • If no pins are felled on the 1st, 2nd, and 3rd rolls, but all 20 on the 4th roll, it counts as only a spare.
Last frame.
In the 5th frame, the bowler is presented a full rack of 5 pins, and rolls the ball 1 or 2 times.

If all 5 pins are felled on the 1st roll, it is a spare, and the bowler gets 1 addtional roll.
otherwise …
It is an open frame, and the bowler does not get a 2nd roll.

In the 10th frame, the bowler is presented a full rack of 10 pins, and rolls the ball 2 or 3 times.

If all 10 pins are felled on the 1st roll, it is a strike, and the bowler gets 2 addtional rolls.
otherwise …
If all remaining pins are felled on the 2nd roll, it is a spare, and the bowler gets 1 addtional roll.
otherwise …
It is an open frame, and the bowler does not get a 3rd roll.

In the 15th frame, the bowler is presented a full rack of 15 pins, and rolls the ball 3 or 4 times.

If all 15 pins are felled on the 1st roll, it is a star, and the bowler gets 3 addtional rolls.
otherwise …
If all remaining pins are felled on the 2nd roll, it is a strike, and the bowler gets 2 addtional rolls.
otherwise …
If all remaining pins are felled on the 3rd roll, it is a spare, and the bowler gets 1 addtional roll.
otherwise …
It is an open frame, and the bowler does not get a 4th roll.

In the 20th frame, the bowler is presented a full rack of 20 pins, and rolls the ball 4 or 5 times.

If all 20 pins are felled on the 1st roll, it is a diamond, and the bowler gets 4 addtional rolls.
otherwise …
If all remaining pins are felled on the 2nd roll, it is a star, and the bowler gets 3 addtional rolls.
otherwise …
If all remaining pins are felled on the 3rd roll, it is a strike, and the bowler gets 2 addtional rolls.
otherwise …
If all remaining pins are felled on the 4th roll, it is a spare, and the bowler gets 1 addtional roll.
otherwise …
It is an open frame, and the bowler does not get a 5th roll.

Whenever the bowler is entitled to another roll but no pins are standing, a fresh rack of 5 pins is provided.

As before, felling all of them on the 1st try counts as a spare.

Whenever the bowler is entitled to another roll but no pins are standing, a fresh rack of 10 pins is provided.

As before, felling all of them on the 1st try counts as a strike, and in 2 tries (if 2 rolls remain) a spare.

Whenever the bowler is entitled to another roll but no pins are standing, a fresh rack of 15 pins is provided.

As before, felling all of them on the 1st try counts as an star, on 2 tries (if 2 rolls remain) a strike, and on 3 tries (if 3 rolls remain) a spare.

Whenever the bowler is entitled to another roll but no pins are standing, a fresh rack of 20 pins is provided.

As before, felling all of them on the 1st try counts as a diamond, on 2 tries (if 2 rolls remain) a star, and on 3 tries (if 3 rolls remain) a strike, and on 4 tries (if 4 tries remain) is a spare.

Earned is 1 point for each pin felled in this frame; no bonuses are earned for marks.

Still, pins felled in the 5th frame can fulfill a bonus earned in the 4th frames

Earned is 1 point for each pin felled in this frame; no bonuses are earned for marks.

Still, pins felled in the 10th frame can fulfill bonuses earned in the 8th and 9th frames.

Earned is 1 point for each pin felled in this frame; no bonuses are earned for marks.

Still, pins felled in the 15th frame can fulfill bonuses earned in the 12th, 13th and 14th frames.

Earned is 1 point for each pin felled in this frame; no bonuses are earned for marks.

Still, pins felled in the 20th frame can fulfill bonuses earned in the 16th, 17th, 18th and 19th frames.

The 5th is the only frame in which a bowler can earn more then 1 mark, the combination being:
  • 2 spares
The 10th is the only frame in which a bowler can earn more then 1 mark. The multi-mark combinations are:
  • 3 strikes
  • 2 strikes
  • 1 strike and 1 spare
The 15th is the only frame in which a bowler can earn more then 1 mark. Some of the multi-mark combinations are:
  • 2, 3, or 4 stars
  • 1 star and 1 strike
  • 2 strikes
The 20th is the only frame in which a bowler can earn more then 1 mark. Some of the multi-mark combinations are:
  • 2, 3, 4, or 5 diamonds
  • 2 or 3 stars
  • 1 star and 1 spare
  • 1 diamond and 2 stars
Perfect score.
50 = 5 × 10, requiring 6 rolls 300 = 10 × 30, requiring 12 rolls 900 = 15 × 60, requiring 18 rolls 2000 = 20 × 100, requiring 24 rolls

Notes.

As before, marks are denoted by special symbols with the number of strokes equalling the number of bonus rolls:

  • spare
  • strike
  • star
  • diamond

The numbers work out most elegantly in the 10-pin and 15-pin versions, and that is why they got treated on the main page. As for the 5-pin and 20-pin versions, some players may choose to fill the gap in the triangular arrangement of the pins, obtaining perhaps:

  • a 6-pin game with 6 frames and a perfect score of 72 = 6 × 12.
  • a 21-pin game with 21 frames and a perfect score of 2205 = 21 × 105.
The 5-pin and 20-pin arrangements were chosen for detailed presentation because they have more round numbers.