How many matches is a round-robin?

n(n−1)/2 for a single round-robin, because every pair of entrants meets exactly once and there are that many pairs. Double it for home and away. Eight entrants is 28 matches, sixteen is 120, and twenty-four is 276 — the growth is quadratic, which is why round-robins stop being possible so abruptly.

How many rounds does a knockout take?

⌈log₂ n⌉ — each round halves the field, so sixteen entrants is four rounds and thirty-two is five. The match count is n−1, because every entrant except the winner loses exactly once.

Why does more pitches not always make it faster?

Because rounds are sequential. The second round of a knockout cannot start until the first has finished, so a bracket of sixteen takes at least four rounds' worth of time however many pitches you have. Parallel capacity compresses a round-robin, where matches are independent, far more than a knockout.

No, it is a calculator, and it sits alongside the generators because it answers the question that comes first. Deciding whether a format fits happens before anybody has an entrant list, and asking somebody to type twenty-four names to find out the answer is "no" would be the wrong way round.

Tournament Match Calculator

Almost every argument about tournament format is really an argument about arithmetic nobody has done. Sixteen entrants is fifteen matches as a knockout and a hundred and twenty as a round-robin — those are not two versions of the same event. This does the sums for every format at once, so the choice is made with the numbers in front of you rather than after the fixtures are published.

Entrants

Teams or players.

Minutes per match

Including the changeover — a ten-minute match is realistically a thirteen-minute slot.

Pitches available

How many matches can run at once.

Groups

For the groups-then-knockout row.

Qualify per group

Two is usual.

Your format comparison will appear here.

What this generator does

Calculates, for the number of entrants you enter, how many matches and rounds each common format needs: single knockout, double elimination, single and double round-robin, Swiss, and groups feeding a knockout. It then converts those into elapsed time given a match length and the number of pitches available, which is the number people actually need and almost never work out. Nothing here is random — it is arithmetic, and the formulas are shown so you can check them.

How to use this tool

Enter how many entrants you have.
Optionally set how long a match takes and how many pitches or tables you have.
Read the comparison. Every format is costed in matches, rounds and rough elapsed time.
Pick a shape, then draw it with the matching generator.

Understanding the controls

Entrants: How many teams or players. The formats scale very differently: doubling the entrants roughly doubles a knockout and roughly quadruples a round-robin, which is the single most important fact on this page.
Match length: Including any changeover. A ten-minute match with a two-minute changeover is a twelve-minute slot, and using the playing time alone is how a schedule ends up an hour over.
Pitches available: How many matches can run at once. This divides the elapsed time but not below the round count — a knockout of eight cannot finish faster than three rounds however many pitches you have, because each round needs the previous one's results.
Groups and qualifiers: For the group-and-knockout row. Changing these changes the shape considerably, and the row shows whether the qualifiers fill a bracket exactly or need byes.

Worked examples

8 entrants: Knockout: 7 matches, 3 rounds. Round-robin: 28 matches, 7 rounds. Four times the matches.
16 entrants: Knockout: 15 matches. Round-robin: 120. At 15 minutes a match on two pitches, that is under two hours against fifteen.
24 entrants: Round-robin is 276 matches — a season rather than a day. Six groups of four then a knockout is 36 + 15 = 51.
Why rounds matter: A knockout of 32 on twenty pitches still takes five rounds, because each round needs the last one's results.

Common use cases

Deciding a tournament format before committing to it
Working out whether a competition fits in the hours available
Explaining to a committee why a round-robin for twenty is not possible
Booking the right number of pitches, courts or tables
Checking a league season's fixture count against the available weekends

How this generator works

Every figure is a formula rather than a simulation. A single knockout is n−1 matches, because every entrant but the winner is eliminated exactly once, over ⌈log₂ n⌉ rounds. A round-robin is n(n−1)/2, because every pair meets once. Double elimination is about 2n−2, because almost everybody has to lose twice. Swiss is the rounds you choose times ⌊n/2⌋. The elapsed-time estimate divides the match count by the pitches available, then takes whichever is larger: that figure, or the round count — because rounds are sequential by definition and no amount of parallel capacity compresses them.

Randomness and fairness

Nothing here is random at all. Every number is a formula applied to what you entered, so the same inputs always give the same answer — which is worth stating plainly on a site full of generators. This one is a calculator, and it exists because the question it answers comes before any draw is made.

For how randomness is produced across the whole site, see how Generate Random works.

Assumptions this tool makes

Every match involves exactly two sides and produces a result.
Rounds are sequential: a round cannot start before the previous one has finished.

Limitations and good to know

The time estimate assumes matches start promptly and pitches are used continuously. Real tournaments lose time to overruns, injuries, and people not being where they said they would be — add a quarter and you will be closer.
It does not account for rest between matches for the same team, which a real schedule must. In a knockout the same teams play consecutive rounds, and back-to-back matches are unfair as well as unsafe.
Swiss round counts are a convention rather than a formula. The usual choice is ⌈log₂ n⌉, and competitions vary.
Third-place playoffs, consolation brackets and repechage rounds add matches this does not count.
It is a calculator, not a scheduler. It says how many matches, not when each one is.

Common mistakes

Assuming a round-robin scales like a knockout: It does not. Doubling the entrants roughly doubles a knockout and roughly quadruples a round-robin, because the match count is quadratic. Eight entrants is four times the matches; twenty-four is twelve times.
Dividing total matches by pitches and calling that the time: Rounds are sequential. A knockout of sixteen takes four rounds however many pitches you have, because each round needs the previous one's results. The calculator takes whichever is larger.
Using playing time rather than slot time: Add the changeover, the walk between pitches and the delay while somebody finds the ball. A ten-minute match is realistically a thirteen-minute slot.
Forgetting teams need rest: A team in a knockout plays every round. Back-to-back matches with no gap are unfair and, in a physical sport, unsafe — build the gaps into the schedule rather than into the match count.

Practical tips

Work out the format before the entrant list is final. The numbers change shape sharply between twelve and sixteen entrants, and knowing that early saves a redraw.
Add 25% to whatever the time estimate says. Every tournament runs over, and the ones that do not started late.
If the round-robin figure is impossible, look at groups before you look at a knockout. Groups keep the guaranteed-matches benefit that makes a round-robin attractive in the first place.

Troubleshooting

The time estimate looks impossibly short: It assumes continuous play with no gaps at all. Real events lose time everywhere; treat it as a floor rather than a plan.
The group row shows byes: The qualifiers do not reach a power of two. Change the number of groups — four or eight groups with two qualifying gives eight or sixteen exactly.

Privacy and your data

Nothing is entered beyond a handful of numbers, and nothing is stored. The calculation happens in your browser and analytics records only that the tool was used.

Frequently asked questions

How many matches is a round-robin?: n(n−1)/2 for a single round-robin, because every pair of entrants meets exactly once and there are that many pairs. Double it for home and away. Eight entrants is 28 matches, sixteen is 120, and twenty-four is 276 — the growth is quadratic, which is why round-robins stop being possible so abruptly.
How many rounds does a knockout take?: ⌈log₂ n⌉ — each round halves the field, so sixteen entrants is four rounds and thirty-two is five. The match count is n−1, because every entrant except the winner loses exactly once.
Why does more pitches not always make it faster?: Because rounds are sequential. The second round of a knockout cannot start until the first has finished, so a bracket of sixteen takes at least four rounds' worth of time however many pitches you have. Parallel capacity compresses a round-robin, where matches are independent, far more than a knockout.
Is this a generator?: No, it is a calculator, and it sits alongside the generators because it answers the question that comes first. Deciding whether a format fits happens before anybody has an entrant list, and asking somebody to type twenty-four names to find out the answer is "no" would be the wrong way round.