How a Five-Pick Round Robin Works: Pairs, Triples, and Payouts

In US sportsbook usage, a round robin is a set of separately staked parlays built from your picks, using the combination sizes you select, such as By 2s or By 3s. Five picks produce 10 two-pick parlays or 10 three-pick parlays. At $2 per parlay, either set costs $20; selecting both creates 20 parlays with a total stake of $40. This differs from the usage at some UK bookmakers, where Round Robin means a fixed 10-bet system with three selections, as shown in Betfred’s official Round Robin calculator.

A round robin can return money even when some picks lose, but that does not guarantee a profit. In the hypothetical example below, three of five picks win. The pairs return $18.60 gross for a net loss of $1.40; the triples return $10.80 gross for a net loss of $9.20.

What do “By 2s” and “By 3s” mean?

By 2s means all two-pick combinations, while By 3s means all three-pick combinations. Each combination is a separate parlay with its own stake.

The number of combinations is C(n,k) = n! / k!(n−k)!, where n is the number of picks and k is the number of picks in each parlay.

Five picks happen to produce the same number of pairs and triples. That does not make the tickets equivalent: their combinations and potential returns differ.

DraftKings’ round robin explanation describes separately staked pairs and notes that choosing all combinations adds another parlay size. bet365’s explanation also discusses choosing a combination size and staking each parlay. Check which sizes you selected rather than relying on the number of picks alone.

What assumptions does this five-pick example use?

This example uses five hypothetical, compatible picks at decimal odds, with A, B, and C winning and D and E losing. The stake is $2 per parlay, not $2 for the whole ticket.

This is not an actual wager or an offer to bet at these odds. It assumes ordinary win-or-loss settlement, with no voided picks, bonuses, taxes, payout limits, or operator-specific rounding differences. Potential returns are displayed to the nearest cent; the rounded BDE figure is noted below.

A parlay wins only if every pick in it wins. Its gross return equals the stake per parlay multiplied by the decimal odds of every pick in that combination. Gross return includes the winning parlay’s stake. To find the net result, subtract the total original stake across all component parlays—not just the stakes on the winners.

For either size alone, the total stake is C(5,k) × $2 = $20.

By 2s: which of the 10 pairs win?

AB, AC, and BC win, producing a gross return of $18.60. The other seven pairs contain D or E and return nothing.

For example, AB returns $2 × 2.00 × 1.80 = $7.20.

The pairs ticket settles as follows:

• Total stake: 10 × $2 = $20.
• Gross return: $7.20 + $6.00 + $5.40 = $18.60.
• Net result: $18.60 − $20 = −$1.40.

Three winning picks produce three winning pairs here, but their combined returns do not cover the cost of all 10 parlays.

By 3s: which of the 10 triples win?

Only ABC wins, producing a gross return of $10.80. Every other triple contains at least one losing pick.

ABC returns $2 × 2.00 × 1.80 × 1.50 = $10.80.

Potential returns are shown to the nearest cent. BDE’s potential return is rounded; because BDE loses, that rounding does not affect this example’s gross return.

The triples ticket settles as follows:

• Total stake: 10 × $2 = $20.
• Gross return: $10.80.
• Net result: $10.80 − $20 = −$9.20.

What happens if you select both pairs and triples?

Selecting both sizes at $2 per parlay puts $40 at risk, returns $29.40 gross, and leaves a net loss of $10.60.

The last row combines both sets: $18.60 + $10.80 = $29.40 gross, then $29.40 − $40 = −$10.60 net. The stake per parlay stays the same, but the number of paid parlays doubles. This is not a comparison using the same total budget.

How can you check the example in the calculator?

The ToolsGambling round robin calculator lets you check combination counts, total stakes, scenario payout ranges, and potential returns for individual parlays. It does not let you mark individual picks as actual winners. To reproduce the A/B/C result, manually select the relevant component returns from the Pro list and add them.

1. Click + Add selection once to add a fifth selection to the four initial fields. Enter the decimal odds in A–E order: 2.00, 1.80, 1.50, 2.20, 1.60. Rename the editable selection-name fields A, B, C, D, E, respectively.
2. Leave only By 2s selected. Deselect any other active sizes; each size button is an independent toggle.
3. Enter 2 in Stake per parlay.
4. Check for 10 combinations and a $20 total stake.
5. In Pro, find A + B, A + C, and B + C. Their potential returns are $7.20, $6.00, and $5.40. For the scenario where only A, B, and C win, manually identify these winning components and add their returns: $18.60. Pro shows potential returns; it does not determine which selections won.
6. Deselect By 2s, then select By 3s, keeping Stake per parlay at 2. If you leave By 2s selected, both sizes remain active.
7. Check for 10 combinations and a $20 total stake. For the same scenario, manually count only the return for A + B + C: $10.80.

The calculator also shows a payout range for a given number of winning picks. Its verified three-win payout bands for these inputs are:

The payout range does not identify A, B, and C as the winners. It covers different possible sets of three winning picks. It is neither a probability interval nor an expected return: even with the same number of winners, the payout changes depending on which picks win and their odds.

How do you avoid confusing stake per parlay with total stake?

Before confirming a sportsbook ticket, check whether its stake entry means the amount per parlay or the total amount split across the parlays. Operator stake-entry conventions vary.

In this example, $2 funds each of the 10 component parlays, not the entire ticket. The bet365 example uses a per-parlay amount. Keep that distinct from the total stake: selecting both two-pick and three-pick parlays at $2 each costs $40 overall.

Inspect the accepted bet slip and reconcile three numbers: the combination count, stake per parlay, and total stake. For either the pairs-only or triples-only ticket here, the check is 10 × $2 = $20.

For other combination structures, see the broader guide to system bets.