## Introduction

**Boxrec** provides *Current* and *All Time* boxer ratings, as calculated daily by its computer. These ratings are not influenced by subjective views or opinions but are wholly dependent upon the bouts contained in the BoxRec database.

The *All Time* (or “All Boxers”) ratings include both “Inactive” (retired) and “Active” boxers. The *Current*
ratings include only those boxers who have fought a bout within the
past 365 days (“Active”). (After a year of not fighting, a boxer is
automatically designated “Inactive” by the BoxRec computer. A boxer is
also designated “Inactive” if he has announced his retirement, even if
he may have had a bout within the past 365 days.) Every boxer in the
database is rated–even those with an 0-1 record.

The BoxRec computer re-calculates the ratings daily at approximately 9:35 GMT. As the computer refreshes its calculations each and every day, a boxer may gain or lose ratings points with every bout of his entered into the database by a BoxRec Editor since the last daily calculation. A boxer may also gain or lose points if bouts are added to any of his opponents’ records, or to their opponents’ records–even if the boxer himself has not had a fight since the last BoxRec computer calculation.

There admittedly are inaccuracies and anomalies, especially in the *All Time*
ratings, mostly because of incomplete records in the BoxRec database.
Although a boxer’s own record may be complete, his opponents’ records
may not be complete. Pre-World War II boxers in particular are at
somewhat of a disadvantage, vis-à-vis modern boxers. Their opponents’
records often are quite incomplete–because of the scarcity of source
material or Editors’ time–while the records of opponents of more
current boxers may be quite complete. So, for example, while Mike
Tyson’s own record, and those of his opponents, may be complete–thereby
earning Tyson a certain number of points and thus giving him a high
ranking among the *All Time* Heavyweights–the records of Young
Stribling’s opponents may be extremely lacking, thereby giving Stribling
fewer points and a much-lower *All Time* rating. And it may appear
to the casual BoxRec visitor that Stribling had fought many boxers
making their professional debuts or having had only a handful of career
bouts, when the truth is that not all of his opponents’ total career
bouts have been entered into the database. (Too many of those old-time
bouts are forever lost in history because they were not reported by a
newspaper or similar source, or the source was later destroyed.)
However, as BoxRec Editors continue to research older resources and
enter “new” historical bouts into the database, or correct bouts/boxers
previously entered, the rating of an old-time boxer like Stribling may
gradually move up or down, even if his own record is considered
complete, if bouts are added to his opponents’ records, or to their
opponents’ records, and so on.

Finally, because of the very few women presently boxing professionally, with some weight divisions having only a handful of active female boxers, a woman with an 0-1 record will appear “world ranked” by BoxRec. This is simply an anomaly due to the few female entries in the database.

## Ratings Structure

All these ratings evaluate every day all bouts in the database in chronological sequence. A higher rated boxer should be expected to defeat a lower rated boxer with increasing probability by increasing rating difference.

### Current Ratings

- Points are redistributed by every bout. No points come in or get out of the system by this basic rating process
- But points get out of the system by career end, by point reductions due to inactivity or missing opponent quality
- So additional points must be fed into the system
- – 0.01 point, when a boxer wins a bout
- – 0.1 points, when a boxer defeats an opponent, who already won a bout within 18 months
- – 1 point, when a boxer defeats an opponent, who already won a bout against a winning opponent within 18 months
- – when defeating an opponent within the top 15 percent of all active boxers, who already defeated an opponent within the top 15 percent of all active boxers
- — 8 points at least
- — as much points as the defeated opponent had before the bout
- — 40 points at most
- — with weight = 1, when the opponent had no loss after his top win, with weight = 1/2 after 1 loss, with weight = 1/4 after 2 losses etc
- — with weight = 1 within 18 months after the opponents top bout, with weight = 1/2 thereafter and decreasing by a factor of 1/2 per another 18 months
- – all with weight = cd * v; cd = clear decision factor and v = bout value
- Every boxer gets a first rating of 0 before his first bout.
- After every bout, the ratings of the two boxers involved are changed depending on the bout’s official result (KO, TKO, RTD, UD, PTS, NWS, MD, SD, DQ, TD, DRAW).
- The value of a result varies between v=1 and v=0.
- The clear decision factor varies between cd=1 and cd=0.
- The winner cannot lose points for KO, TKO, RTD, DQ, TD and decisions on points with cd=1
- KO, TKO, RTD are rewarded with full value v=1, cd=1.
- NWS is rewarded with full value v=1 for 12 rounds boxed and more and a lower value related to the number of rounds boxed. Clear decision factor cd=1.
- UD, PTS, DQ, TD are rewarded with full value v=1 for 12 rounds boxed and more and a lower value related to the number of rounds boxed, clear decision factor cd=1. If the score cards are available, it may be less.
- MD, SD are rewarded with full value v=1 for 12 rounds boxed and more and a lower value related to the number of rounds boxed. Clear decision factor is limited to cd=0.5. If the score cards are available cd may be less.
- DRAW is rewarded with full value v=1 for 12 rounds boxed and more and a lower value related to the number of rounds boxed. Clear decision factor cd=0.
- If the score cards are available, the value rewarded is in direct proportion to the rounds boxed, with full value v=1 for 12 rounds boxed and more. The clear decision factor is in proportion to rounds boxed and the mean score difference per judge. cd=1 for a mean score difference per judge of 50% of the rounds boxed.
- All bouts are regarded to have the same weight independent of titles.
- The winner gets a certain part of the opponent’s points and a certain part of the rating difference to the opponent’s rating.
- For a DRAW the rating of the higher rated boxer is reduced by some part of the point difference; the rating of the lower rated boxer is enhanced by the same amount of points.
- The full relative point reward is 33%. It is in direct proportion to the pre-bout rating of the defeated opponent.
- The rating of a boxer is reduced, if he didn’t box an opponent with a rating of at least 50% of his own rating points within 18 months.
- The rating of a boxer is reduced by up to 50% in proportion to the difference of 2 times the rating points of his best opponent in this time period minus his own rating
- The reduction is in proportion to the time the requirement was missed.
- The rating of a boxer is reduced by 50% for every time period of inactivity of 18 months – and to even less in proportion to a longer time period of inactivity
- The pre-bout rating of a successfully debuting boxer is set to 25% of his opponents pre-bout rating.
- The rating points are in relation to a weight division. The rating points are converted with the cube of the upper weight limit ratio of the old and new weight division.
- The winner is always rated higher than the loser. the minimum margin is: mean pre-bout ratings of both r_m = (r_a + r_b)/2; r_new_winner = r_m + earn_f*v*cd/4; r_new_loser= r_m – earn_f*v*cd/4

**Formula**

If a boxer with a rating of r_a before the fight defeats a boxer b with a rating of r_b before the fight with result of value v, clear decision factor cd, the new regular ratings r_a_new and r_b_new after a fight are:

- earn = 1/3 * v * (r_b*cd + (r_b-r_a)/(1+2*cd));
- r_a_new = r_a + earn_a
- r_b_new = r_b – earn_b

The winner gets additional points.

Rating reduction caused by missing opponent quality:

career_top_rating = highest career rating adapted to bout division days = days between bout with best opponent before and bout with best opponent after reduction

- r_red-career_top_rating/10 = (r_old-career_top_rating/10) * (1 – 0.5*(1 – 2*best_opp/r_old))**(days/(365.24*1.5))

**Examples**

*Boxer a UD 6 boxer b, scores 59:55 58:56 58:56, a has 10 points, b
has 5 points, opponent with a prior win, but not within the top 15
percent of all active boxers*

- A 6 rounder is rewarded with value 6/12, v=0.5
- UD is rewarded with cd=1 at maximum
- mean score difference per judge is (4+2+2)/3 = 2.667, which is rewarded in direct proportion to half the rounds boxed with cd= 2.667/3 = 0.89 at maximum
- so cd=0.89

- earn= 1/3 * 0.5 * (5*0.89 + (5-10)/(1+2*0.89)) = 0.63
- r_a_new = 10 + 0.63 = 10.63
- r_b_new = 5 – 0.63 = 4.37

- Winner additionally gets 0.01 points + 0.1 points for opponent with win and weight = cd*v = 0.89*0.5= 0.445
- additional points = 0.11*0.445 = 0.05 points
- r_a_new = 10.63 + 0.05 = 10.68

*Boxer a SD 8 boxer b, scores 77:75 77:75 75:77, a has 100 points, b
has 50 points, opponent within the top 15 percent of all active boxers
and with an own win against such a top 15 percent boxer 23 months ago
and 1 following loss*

- A 8 rounder is rewarded with 8/12, v=0.667
- SD is rewarded with cd=0.5 at maximum
- mean score difference per judge is (2+2-2)/3 = 0.667, which is rewarded in direct proportion to half the rounds boxed 0.667/4 at maximum
- so cd=0.167

- earn= 1/3 * 0.667 * (50*0.167 + (50-100)/(1+2*0.167)) = -6.48
- r_a_new = 100 – 6.48 = 93.52
- r_b_new = 50 + 6.48 = 56.48

- Winner additionally gets 0.01 points + 0.1 points for opponent with win + 1 point for opponent with a win against a winner
- + 40 points for opponent with top 15 percent win with weight=1/2 for 1 following loss and weight=0.41 for top win before 22 months
- and overall weight = cd*v = 0.5*0.67= 0.0.333
- additional points = (1.11 + 40*0.5*0.41)*0.333 = 3.10 points
- r_a_new = 93.52 + 3.10 = 96.62

### All Time Ratings

The All Time Rating for a boxer is the sum of annual rank points of best defeated opponent at time of bout and the square root of his career top rating:

- best opponent rank points = 200/ (best opponent rank – 1) for annual rating (if rank is 1 use rank 1)
- best opponent p4p rank points = 200 / (best opponent p4p rank – 1) for annual rating (if rank is 1 use rank 1)
- the ranks are interpolated in relation to the ratings of boxer ranked before him and the boxer behind him
- the best opponent rank points are limited to the lowest rank points of the opponent, he lost to in this year – pair by pair
- the value of 200 annual points is reduced, if the annual rating of #30 in the division is less than 76.3 for men, or less than 3.86 for women
- the value of 200 annual p4p points is reduced, if the annual rating of #50 p4p is less than 279 for men, or less than 12.2 for women

### Bout Star Ratings

All bouts are rated with 0 to 5 stars.

Men

- 5 stars = both opponents have 279 rating points at least ~ best 100 boxers
- 4 stars = both opponents have 122 rating points at least ~ best 300 boxers
- 3 stars = both opponents have 40.5 rating points at least ~ best 900 boxers
- 2 stars = both opponents have 5.92 rating points at least ~ best 2700 boxers
- 1 stars = both opponents have 0.428 rating points at least = best 8100 boxers
- 0 stars = one opponents has not even 0.428 rating points at least = not rated boxers

Women

- 5 stars = both opponents have 12.2 rating points at least ~ best 50 boxers
- 4 stars = both opponents have 6.15 rating points at least ~ best 100 boxers
- 3 stars = both opponents have 2.20 rating points at least ~ best 200 boxers
- 2 stars = both opponents have 0.554 rating points at least ~ best 400 boxers
- 1 stars = both opponents have 0.023 rating points at least = best 800 boxer
- 0 stars = one opponents has not even 0.023 rating points at least = not rated boxers