Rules and Regulations

Updated: Sep. 6, 2019

ISI Slackline Judging is a slackline judging system that is made by slackliners and for slackliners in order to provide the most fair, transparent and objective slackline competitions as possible.

1.Competition Format

ISI competitions will NOT use seeding to set competition match-ups. Alternatively, ISI competitions assign head-to-head athlete selections to the matches by random drawing (ex: if there are 24 competitors in a round, a drawing will occur to select the order and head-to-head pairings for the first 12 matches). If there is an odd number of competitors, then once the last name is drawn for that round, all of the previously chosen numbers will go back in and a number will be drawn to compete against the last person. The score for athlete #2 of this match will count as their 2nd match score for this round.

Athletes will compete head-to-head in 90-second matches, earning individual scores based on trick variety, trick difficulty, trick combos, amplitude & style. Each athlete will compete in two individual matches (heats) per round, which will be chosen at random each time. The highest individual score from each athlete’s two matches will be retained to determine who moves on to the next round. At the end of the 90-second run, an audible alarm will sound, notifying the athlete that they have 15 seconds remaining to complete their last trick or combo sequence. At the end of this 15-second bonus time, the final alarm will sound notifying the judges that the run is over. Any tricks performed after this alarm will not be scored. Any combo sequences in progress after this alarm will not be scored; meaning that if an athlete is mid-combo and the final alarm sounds, there will be no combo points awarded and only tricks up to the alarm sounding will be counted.

A leaderboard will be posted and the top the athletes will move on to the next round. In the event of a tie, athletes will be given a one-minute match to determine who moves through.

Final rounds will utilize the exact same format as the preliminary rounds. Each of the finalists will get two matches/heats selected at random and the best score from each athlete’s two matches will determine 1st through 8th place finishes.

The number of rounds will depend on the number of athletes, event organizer and how many days the event is to last. At a minimum there will be at least two rounds with two heats, qualifier and finals.

CASE1 -  Competition format with 32 or more athletes (for 2 days)

32 athletes 16 8

CASE2 - Competition format with 20 athletes (for 2 days)
20 16 8

CASE3 - Competition format with 20 athletes (for 1 days)
20 8

Line must have a height of at least 48 inches (1.2192 meters) and a length of at least 55 feet (16.764 meters).


Each match will be watched live and recorded on video to be reviewed the judges. At least one judge will act as the Overall Performance, Amplitude, and Cleanliness Judge (OPAC Judge). They will watch each match live and record the Overall Performance, Amplitude, and Cleanliness scores for each match.
(* 'Cleanliness' was automatically calculated from 2019.)

At least two judges will act as the Scoring Judges to record the Individual Tricks, Steeze, Combos and Dabs (deductions) into the scoring sheet for each athlete and verify the Overall Performance, Amplitude and Cleanliness score using the video of the match to determine the final score.

3.Individual Trick Scoring

Scoring judges will be looking for variety in each athlete’s ability to perform tricks. Repeating the same trick over and over will not benefit an athlete’s final score as much as a variety of tricks. Any single trick performed more than three times in an individual match will not be acknowledged in the judge’s recordings. Additionally, after a trick is successfully performed the first time, each successive successful completion of that trick (up to a maximum of three) will receive a reduced point value based on a standardized declining point scale. The number of times a trick is performed will start at zero at the beginning of each match.


The same trick performed four or more times in each heat, regardless of whether it is a single trick, a combo, or a sequence, is worth zero points. In addition, the second trick in one heat is scored -25% from the reference point, and the third trick is scored -50% from the reference point.

CASE -  Trick: Misty Buttflip FS (reference point: 11.042 points) repeated 1-4 times in one heat

1st time 2nd time 3rd time 4th time or later
* This penalty will be counted for each heat. Therefore, it will be reset at the start of the next heat and will be counted from zero.


Frontside (FS) and Backside (BS) are considered separate tricks.

CASE - FreeFall 360 (reference point:4.746pt)

1st time 2nd time
f/s FreeFall 360
b/s FreeFall 360
*f/s : frontside
*b/s : backside

* Initially, some tricks had different scores on the front side and the back side, but they were unified in 2019. This is because, in recent years, slack line techniques have been established to some extent, and the difference in difficulty between the front side and the back side has been determined to be mostly due to "subjectivity and individual preference of individual athlete".


If a switch trick is performed, a +25% bonus point will be added to the base point of the trick.

NOTE - However, there are the following three patterns for "trick by switch".
1. When both start and end moves are switch stance.
2. When the start move is regular stance and the end move is switch stance.
3. When the start move is a switch and the end move is regular.

In addition, a 270, 450, 630, etc. rotation trick are naturally switch tricks.Therefore, since the reference point has already been set for this trick, the switch bonus will be added in ISI only in the case of 1. In the case of 2 or 3, only the reference point is added and not the additional target.

Butt 270 to Chest (FakeFall 270)  - reference point:3.069pt
Butt 360 to Chest (FreeFall 360) - reference point:4.746pt

  start end point
1. switch switch 5.933pt
(+25% up)
(FreeFall 360)
2. regular switch 3.069pt
(0% up)
(FakeFall 270)
3. switch regular 3.069pt
(0% up)
(FakeFall 270)
* A switch bonus should be granted only in the case of "1.".


Additional points can be earned on individual tricks by the addition of “Steeze” to a trick. Steeze is combination of the words “style and ease” and in this case it refers to any grabs or variations on scored tricks. A bonus of up to 50% points can be earned per trick depending on the difficulty of the grab or variation.

CASE - Butt Backflip to Butt with a Squirrel Grab (reference point:5.159pt)

Steeze Point
Level1 5.675pt
Level2 6.191pt
Level3 6.707pt
Level4 7.223pt
Level5 7.739
* Normal tricks and tricks with added steeze are treated as "same tricks". Therefore, if you perform the same trick multiple times in a single heat, you will be deducted regardless of whether or not you have steeze.

4.Combo Scoring

Combos are a great way for an athlete to increase their score and demonstrate a high level of body control and mastery of the slackline during their match. When a trick is performed in a combo sequence, the judge will record the trick in the spreadsheet and indicate whether it was part of a combo or not. If performed in a combo, the trick will receive a 18-70% bonus (on original full point trick value including any dabs) added to the original value of the trick, known as the "Dynamic Combo Bonus". Each trick will receive a bonus percentage that depends on the difficulty of the tricks performed before, after and throughout the combo. To receive the highest possible Dynamic Combo Bonus, the athlete must perform combos that contain high point tricks in long combination.


NO COMBO - [Freefall BS 360 (4.746 pt) + Flat Spin 360 FS (6.256 pt) + Spiral BS (5.955 pt)] = 16.957 pt

COMBO - [Freefall BS 360 (6.035 pt) 27% + Flat Spin 360 FS (8.269 pt) 37% + Spiral BS (7.573 pt) 27%] = 21.877 pt

COMBO - [Freefall BS 360 (6.245 pt) 32% + Flat Spin 540 FS (23.422 pt) 32% + Spiral BS (7.835 pt) 32%] = 37.502 pt

COMBO - [Freefall BS 720 (30.142 pt) 32% + Flat Spin 540 FS (24.596 pt) 39% + Spiral BS (7.835 pt) 32%] = 62.573 pt


NO COMBO - [Buttflip (5.047 pt) + Butt Backflip (5.159 pt)] = 10.206 pt

2 TRICK COMBO - [Buttflip (6.282 pt) 24% + Butt Backflip (6.418) 24%] = 12.70 pt

4 TRICK COMBO - [Buttflip (6.535 pt) 29% + Butt Backflip (6.954) 35% + Buttflip (5.549 pt) 35% + Butt Backflip (5.386 pt) 29%] = 24.424 pt

6 TRICK COMBO - [Buttflip (6.888 pt) 36% + Butt Backflip (7.315) 42% + Buttflip (5.903 pt) 42% + Butt Backflip (6.026 pt) 42% + Buttflip (4.641 pt) 42% + Butt Backflip (4.457 pt) 36%] = 35.23 pt

Individual performance of any given trick will only earn trick points on the first 3 occurrences in a match. However, additional performances of that trick will continue to earn combo points (ex: a trick is performed in combo routines four times during a match by an athlete. The athlete will only receive credit for successfully completing the trick the first 3 times, but will receive credit for performing it in combo all 4 times.

IMPORTANT: The last trick in the combo must be LANDED with no more than a “4” DAB in order to receive combo points. If the last trick in a combo sequence is not under control, the athlete falls off the line or a significant controlled fall is required for the athlete to exit the line, then combo points WILL NOT BE AWARDED for any of the tricks in that run by the judges. Significantly, only points for those individual tricks under control & completed up to the point of the last trick (fall) will be awarded, and NO combo points will be awarded.


To promote a greater variety of combos in competition, repeated combos will only earn a combo bonus on the first three occurrences of the exact same combo in a match.


[Double Butt Backflip + Freefall 360 BS]

1st completion of combo - [Double Buttback Flip 15.80 combo points + Freefall 360 BS 2.38] = 18.18 combo points (100%)

2nd completion of combo - [Double Buttback Flip 15.80 combo points + Freefall 360 BS 2.38] = 13.64 combo points (75%)

3rd completion of combo - [Double Buttback Flip 15.80 combo points + Freefall 360 BS 2.38] = 9.09 combo points (50%)

4th completion of combo - [Double Buttback Flip 15.80 combo points + Freefall 360 BS 2.38] = 0 combo points (0%)

In the example above, combo points no longer are earned as the two-part combo “Double Butt Backflip + Freefall 360 BS” after the 3rd occurrence. The addition of a third trick to the combo or being part of a different two-part combo will still earn points (See example below).


[Double Butt Backflip (4th completion) + Freefall 360 BS (4th completion) + Ascension 360 FS (1st completion)]
1st completion of combo - 26.25 points (100%)


[Double Butt Backflip (4th completion) + Freefall 360 FS (1st completion)]
1st completion of combo - 24.41 points (100%)

NOTE – Butt Bounces and Chest Bounces will be viewed as transition or stabilizing moves by the judges. They will not earn any trick points and will end an existing combo series and initiate the start of a new combo EXCEPT WHEN IMMEDIATELY FOLLOWING A BACK BOUNCE (SEE BACK BOUNCE TRICKS SECTION FOR BACK BOUNCE COMBO EXPLANATION).

5.Cleanliness and Dab Deductions

Cleanliness, otherwise known as the “Cleanliness Penalty” is a percentage, up to 50%, that is increased as a slackliner dabs and is unclean through the run. Light to moderate touching of the floor with hands, feet or body to remain stable and push off the ground as well as shakiness while landing in feet or dropping into "safety" tricks will all increase the Cleanliness Penalty.

At the end of the run, the percentage is deducted from the entire run. If a trick is severely dabbed a 50% or 80% deduction will be applied to the individual trick.

Dab (50% Deduction)
Dabs of 50% deductions that will be applied when the athlete is severely using the ground or line to land tricks and to stay on the line. Landing with flat feet or hands, arms, etc. that stop momentum upon hitting the ground or are used to push off the ground to keep going or stabilize the last trick.

Dab (80% Deduction)
Dabs of 80% deductions are is when the athlete is using a combination of various types of dabs to stay on the line or land tricks that otherwise would have not been landed (ex: landing with 2 feet on the ground and pushing off to get up, landing with both hands and feet on the ground in a chest bounce and then using a sticky to try and stay on the line). The trick receives not only an 80% deduction, but if it is done at the end of a combo there will be no combo points awarded for the entire combo, only individual trick points will be added.

6.Overall Performance & Amplitude Scoring

The OPA Judge(s) will take notice of the “Amplitude” achieved by the athlete during the match and decide to award up to 10 percentage points in this category. The amount received is based upon the average amount of amplitude on every trick scored (more tricks with big amplitude = bigger bonus, more tricks with low amplitude = lower bonus). These points will amplify “Trick Score” earned, excluding points in the “Trick Variety” category.

The “Overall Performance” category offers a total of 10 possible percentage points judges can award. This category is where points for trick variations and grabs on non-scored tricks (Butt Bounce with a grab/Chest Bounce with a grab), line mounts/dismounts, switch and overall performance are awarded. Points will amplify “Trick Score” earned excluding points in the “Trick Variety” category.

The Scoring Judges, after reviewing the match on video, with confirm the scores with the OPA Judge(s) and enter the values into the final score sheet.

7.Trick Variety Score

The final way to earn points is through the “Trick Variety Score”. For each different/unique trick that is successfully landed, the competitor will be rewarded with an additional 4.25 points that will be added to the final score. The number of unique tricks is calculated automatically.

NOTE: Overall Performance and Amplitude bonuses do not apply to the Trick Variety Score.

8.Combo Variety Bonus

The “Combo Variety Bonus” is a bonus multiplier that looks at the number of unique combos performed by an athlete across the entirety of the competition, all heats and all rounds. In order to keep the bonus at the maximum percentage of 25%10%(Revised 2022/09/21) for each match, the athlete must continuously perform different combos.

NOTE: Overall Performance and Amplitude bonuses do not apply to the Combo Variety Score.

9.Back Bounce Tricks

Back Bounce tricks are tricks that involve landing onto the athletes back (ex: Back Bounce, Baximus, Backtastic, Estonian Backflip, Frog Flip to Back Bounce). In order to successfully land a trick that involves a Back Bounce, control must be established by landing either into Chest Bounce, Butt Bounce or to Feet.


[Back Bounce]
>>> to Chest Bounce/Butt Bounce/Standing

[Estonian Backflip]
>>> Standing Backflip to Back Bounce to Chest Bounce/Butt Bounce/Feet

[Frog Flip to Back Bounce (Brazilian Ascension to Back Bounce)[
>>> Chest Bounce to Backflip to Back Bounce to Chest Bounce/Butt Bounce/Feet

To “combo” a Back Bounce trick, the athlete must either execute a scored trick from the Back Bounce or on the next bounce after landing in either Butt Bounce, Chest Bounce or Standing.


[Estonian Backflip + Backtastic]
>>> Standing Backflip to Back Bounce to Front Flip to Butt Bounce

[Estonian Backflip + Flat Spin 360 FS (Mojo Flat 360 FS)]
>>> Standing Backflip to Back Bounce to Chest Bounce to 360 FS Flat Spin to Chest Bounce

[Frog Flip to Back Bounce (Brazilian Ascension to Back Bounce) + Cali Roll]
>>> Chest Bounce to Backflip to Back Bounce to Back Flip to Chest Bounce

10.Static/Dynamic Tricks

Static/Dynamic” tricks are tricks that typically have zero-low amplitude i.e. In-line Buddha, Lady, Crook, spraddle, Double Drop Knee etc. Although they have lower scores than most tricks, they are excellent for increasing your “Trick Variety Score” and can be used to create combos. Comboing “Static/Dynamic” tricks is the same as any other trick as long there is never a significant pause between static tricks and it is not broken up by doing Butt Bounce, Chest Bounce or returning to Feet.

11.Air Tricks

An “Air Trick” starts from a jump from the feet with any sort of grab(s) while airborne and landing back onto the feet. The difficulty level will be accessed by the judges based upon the amplitude of the jump, the amount/type of grabs performed and if it was done in combination.

Air Trick Points
Level 1: 3 points
Level 2: 5 points
Level 3: 10 points
Level 4: 20 points
Level 5: 35 points

12.New Trick Bonus

If a new trick is performed in competition that has never been landed in an ISI competition, it will receive a 30% increase to the points awarded(as a Steeze). This is a one-time bonus and will not be applied anytime the trick is landed in the future. To see which tricks have not been landed in competition please refer to the Trick Scores section of the website. Never landed tricks will be denoted with a "*" at the end of the name of the trick. Tricks that are not on the list can be assumed as not landed as well.

13.Final Score Calculation

The final score will be automatically tabulated for each athlete based on the judge’s assessments. Tricks, Combos, Steeze, Trick Variety, Overall Performance and Amplitude will be recorded into the score sheets. Cleanliness and dab deductions will be subtracted from the points earned on tricks, and a final score will be automatically calculated.