Round Robin Calculator: Combinations, Total Stake and Payout

What a round robin is

A round robin takes a set of selections and places every possible parlay of a chosen size from them. Three selections by twos gives three two-leg parlays. Four by twos gives six. Five by twos gives ten, which is where the phrase about ten bets comes from.

Each of those parlays settles on its own. That is the whole point and the whole difference from a straight parlay. Get two of three selections right on a straight three-leg parlay and you get nothing. Get two of three right on a round robin by twos and one of your three parlays lands, so something comes back.

The cost of that is placing many bets instead of one. Ten dollars a combination across six combinations commits sixty dollars, not ten, and the margin is charged on every one of them. A round robin is not a cheaper parlay; it is a different distribution bought at a higher total outlay.

Reading the results panel

The right-hand column is the part worth studying. It shows what the ticket returns for each number of correct selections, which is the shape a round robin actually has. Three selections by twos at −110 with ten dollars a combination costs thirty dollars. All three correct returns $109.37. Two correct returns $36.46. One correct returns nothing.

That middle row is the reason people place these tickets. It is also the row that makes the comparison honest, because a straight three-leg parlay for the same thirty dollars would return $208.74 if all three landed and nothing otherwise. The round robin gives up more than ninety dollars of upside to convert the two-of-three case from zero into thirty-six.

Whether that is worth it depends entirely on how often you expect to hit two of three rather than three of three, which is a question about your selections; the ticket structure does not decide it. The calculator puts both numbers on the screen and stops there.

Sizes, counts and where it gets expensive

The combination count grows quickly. Six selections by threes is twenty parlays, and at ten dollars each that is a two-hundred-dollar ticket built from what looked like a modest stake. Books present this as a stake per combination precisely because the per-combination figure sounds small, and the total is the number that leaves your account.

The margin scales with the count rather than with the number of selections. Twenty combinations means the book charges its margin twenty times, and the fact that they share underlying legs does not reduce it. This is the structural reason a round robin returns less than the same selections bet straight, regardless of how the games go.

Larger parlay sizes concentrate the payout and shrink the number of combinations, so a six-selection round robin by fours behaves much more like a straight parlay than the same selections by twos. The smaller the size, the flatter the distribution and the more the ticket resembles a set of independent bets with extra margin attached. Moving the size field while watching the results column is the quickest way to feel that trade instead of reading about it.

One assumption to keep in view. Everything here treats the selections as independent, which is the same assumption the parlay calculator makes and it fails for the same reason: legs drawn from the same game move together. Round robins built out of one game are priced by the book through a correlation model, and the arithmetic on this page will overstate what they return.

The comparison worth making is against the simplest alternative. Take the same selections and bet them straight, one at a time, for the same total outlay. The results are then independent, and every winner pays regardless of what the others did. The round robin concentrates the same money into fewer, larger outcomes and charges the margin on every combination to do it.

Neither shape is right in general. Straight bets pay the margin once per selection and settle separately; the round robin pays it on every combination and returns nothing at all unless at least two selections land. What decides between them is how confident you are across the whole set rather than on any one of them, and that is a question about the selections and not about the ticket.