Basketball Rebound Rate Calculator (TRB%, ORB%, DRB%)

Background.

Rebounds per game is one of the most misleading statistics in basketball, because it counts what a player grabbed without asking how much there was to grab. A centre on a team that shoots poorly and plays at a fast tempo sees far more missed shots than one on an efficient, slow team, and will out-rebound him without being any better on the glass. Rebound rate fixes this by measuring what the player took as a share of what was actually available while he was on the floor.

The three formulas, published verbatim by Basketball-Reference, are TRB% = 100 x (TRB x (Tm MP / 5)) / (MP x (Tm TRB + Opp TRB)), ORB% = 100 x (ORB x (Tm MP / 5)) / (MP x (Tm ORB + Opp DRB)) and DRB% = 100 x (DRB x (Tm MP / 5)) / (MP x (Tm DRB + Opp ORB)). This calculator returns all three at once from a single set of inputs, along with total rebounds and rebounds per 36 minutes for context.

The asymmetric denominators are the whole idea and the thing naive versions get wrong. On offence, the rebounds available to you are every rebound of one of your own team's missed shots — which is your team's offensive rebounds plus the opponent's defensive rebounds. On defence it is your team's defensive rebounds plus the opponent's offensive rebounds. Dropping both into a single 'all rebounds' denominator roughly doubles it and halves the answer, which is the most common error in home-made rebound-rate spreadsheets.

The scale is genuinely different for the two halves, and knowing that prevents a lot of confusion. Roughly 76 percent of all rebounds in the NBA are defensive — Basketball-Reference publishes the 2023-24 league defensive rebound rate as 75.8 percent — because defenders start closer to the rim and are already facing the ball. So an individual DRB% of 30 percent is common for a starting big while an ORB% of 30 percent has essentially never happened over a full season. Compare offensive rates against offensive rates and defensive against defensive, never across.

Rebounding is also the third of Dean Oliver's Four Factors of basketball success, weighted at roughly 20 percent, behind shooting and turnovers. At team level the factor is measured with the same availability logic in simplified form: offensive rebound percentage as ORB / (ORB + Opp DRB) and defensive rebound percentage as DRB / (Opp ORB + DRB). The player-level formulas on this page are those same ratios scaled by the share of the team's floor time the player was actually on the court for.

What is rebound rate calculator?

Rebound rate — more precisely total, offensive and defensive rebound percentage — estimates the share of available rebounds a player secured while he was on the floor. Basketball-Reference defines total rebound percentage as 100 * (TRB * (Tm MP / 5)) / (MP * (Tm TRB + Opp TRB)) and describes it as 'an estimate of the percentage of available rebounds a player grabbed while he was on the floor'. The offensive and defensive variants use the same structure with denominators restricted to the rebounds that were actually available on that end: Tm ORB + Opp DRB for offence, Tm DRB + Opp ORB for defence. The Tm MP / 5 term converts team minutes, which count all five positions, into a single-position basis, so the calculation compares the player's rebounding per minute of his own floor time against the rebounding available per minute of one position's floor time. The result is a genuinely context-adjusted number: unlike rebounds per game, it does not reward a player for playing on a team that misses a lot of shots, plays fast, or gives up a lot of misses. It is an estimate rather than an exact measurement because it assumes the rate at which rebounds became available while the player was on the floor matched the team's overall rate — the box score does not record which rebounds occurred during which player's shifts. Basketball-Reference lists these statistics as available from the 1970-71 NBA season onwards, since they require opponent rebounding splits, with individual offensive rebounds themselves first recorded in 1973-74.

How to use this calculator.

1. 01Choose your span — one game or one season — and use it consistently for all eight inputs.
2. 02Enter the player's offensive and defensive rebounds separately. Do not enter a combined total: the two are measured against completely different denominators, and the calculator adds them for you.
3. 03Enter the player's minutes and the team's minutes. Team minutes count all five positions: 240 for a regulation NBA game, 265 with one overtime, and about 19,700 for an 82-game season.
4. 04Enter your team's offensive and defensive rebounds, and then the opponent's. All four are on any box score or team season summary, and the opponent's numbers are essential — without them there is no way to know how many rebounds were available.
5. 05Read total rebound percentage against position-appropriate benchmarks. Around 20% is elite for an NBA centre, 13-16% is typical for a starting big, 8-11% is strong for a wing, and under 6% is normal for a guard.
6. 06Compare offensive rate against offensive rate and defensive against defensive, never one against the other. About 76% of all rebounds are defensive, so a 10% ORB% and a 30% DRB% describe roughly comparable standards of rebounding on the two ends.
7. 07Use rebounds per 36 minutes when you want the raw volume figure — it is what most people mean by 'he's a 12-rebound guy' — but treat the percentages as the more honest comparison between players on different teams.

The formula.

All three formulas share one structure: the player's rebounds, scaled by the share of the team's floor time he occupied, divided by the rebounds that were available to be taken.

The numerator. TRB x (Tm MP / 5) takes the player's rebound count and multiplies it by the team's minutes on a per-position basis. Team minutes count all five positions at once, so a regulation game gives 240 team-minutes while a player can log at most 48. Dividing by five puts both sides of the ratio in the same units.

The denominators. This is where the three formulas differ, and where the reasoning lives. Total rebound percentage divides by Tm TRB + Opp TRB — every rebound either team collected, which is every rebound that existed. Offensive rebound percentage divides by Tm ORB + Opp DRB, because a rebound of one of your team's missed shots was collected either by your team (an offensive rebound) or by the opponent (a defensive rebound), and those are precisely the balls you had a chance at on the offensive glass. Defensive rebound percentage divides by Tm DRB + Opp ORB by the same logic in reverse. Substituting total rebounds into the offensive or defensive denominator — a common mistake — roughly doubles it and halves the answer.

Why DRB% and ORB% live on different scales. Defensive players start closer to the basket, already facing the ball, and are usually in better rebounding position at the moment the shot goes up. Across the whole NBA in 2023-24 the defence collected 75.8% of all rebounds, which Basketball-Reference publishes as the league DRB%, leaving 24.2% for the offence. Any individual player's two rates inherit that asymmetry, which is why 30% DRB% is ordinary for a starting big and 12% ORB% is very good.

What the estimate assumes. The calculation treats the availability of rebounds during a player's minutes as equal to the team's overall availability rate. A box score does not record which rebounds happened during which player's shifts, so this is an approximation — a player who is always on the floor against the opponent's second unit, or who plays exclusively in a lineup that shoots much better than the team average, will have his rate slightly mis-stated in one direction or the other. Over a full season the effect is small; over a handful of games it is not.

Rebounding as a Four Factor. Dean Oliver's Four Factors of Basketball Success weight rebounding at roughly 20%, third behind shooting (40%) and turnovers (25%). At team level Basketball-Reference measures the factor with the same availability idea in simpler form: offensive rebound percentage as ORB / (ORB + Opp DRB) and defensive rebound percentage as DRB / (Opp ORB + DRB), with no minutes scaling because the whole team is on the floor for the whole game.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Basketball-Reference.com Glossary, entries 'TRB%' ("the formula is 100 * (TRB * (Tm MP / 5)) / (MP * (Tm TRB + Opp TRB))"), 'ORB%' ("100 * (ORB * (Tm MP / 5)) / (MP * (Tm ORB + Opp DRB))") and 'DRB%' ("100 * (DRB * (Tm MP / 5)) / (MP * (Tm DRB + Opp ORB))"), each described as an estimate of the percentage of available rebounds a player grabbed while he was on the floor.
2. [2]Basketball-Reference.com, 'Four Factors' — rebounding as the third of Dean Oliver's Four Factors of Basketball Success at approximately 20% weight, measured at team level by ORB / (ORB + Opp DRB) on offence and DRB / (Opp ORB + DRB) on defence.
3. [3]Basketball-Reference.com, 2023-24 NBA season summary — Denver Nuggets team and opponent rebounding totals used in the worked example (Tm ORB 881, Tm DRB 2763, Opp ORB 894, Opp DRB 2573, Tm MP 19705), and the league-wide ORB% of 24.2 and DRB% of 75.8 quoted throughout.
4. [4]Basketball-Reference.com, 2023-24 NBA advanced player table — published rebound percentages used to verify this implementation: Nikola Jokic TRB% 19.8 / ORB% 9.3 / DRB% 29.6, and Rudy Gobert TRB% 21.5.
5. [5]Oliver, D. (2004). Basketball on Paper: Rules and Tools for Performance Analysis. Potomac Books. Origin of the Four Factors framework and of the availability-based approach to measuring individual rebounding.