Round-Robin

A round-robin is a betting structure that takes N legs and splits them into multiple smaller parlays, then bets all of them simultaneously. Instead of one big 5-leg parlay that hits 0% if any leg loses, a round-robin of 5 legs in 3-leg parlays creates 10 separate parlay tickets — many of which can still cash even if one or two legs lose.

How a round-robin works

Pick a set of legs (say 5) and a parlay size (say 3-leg). The book auto-generates every possible combination of 3 from your 5 legs. With 5 legs, there are C(5,3) = 10 different 3-leg combinations:

Legs A, B, C, D, E

Parlays generated:
ABC  ABD  ABE  ACD  ACE
ADE  BCD  BCE  BDE  CDE

Each is a separate parlay with its own price. Your total stake is your per-parlay stake × number of combinations.

Math example

5 legs, all at -110 (decimal 1.91 each). 3-leg round-robin:

• Each 3-leg parlay pays 1.91 × 1.91 × 1.91 ≈ 6.97 (~+597)
• 10 combinations × $5/parlay = $50 total stake

If all 5 legs hit: all 10 parlays cash → 10 × $5 × 6.97 = $348.50 total payout. If 4 of 5 legs hit: C(4,3) = 4 of the 10 parlays cash → 4 × $5 × 6.97 ≈ $139.40. If 3 of 5 legs hit: C(3,3) = 1 parlay cashes → 1 × $5 × 6.97 ≈ $34.85 (loss of ~$15). If 2 or fewer hit: 0 parlays cash → full $50 loss.

Round-robin vs straight parlay

A straight 5-leg parlay at -110 each pays 1.91⁵ ≈ +2,769 — much higher than any single round-robin parlay. But the straight parlay needs all 5 legs. Hit 4 of 5? Zero payout.

The round-robin hits something on 3-of-5, gets back something on 4-of-5, scales up dramatically on 5-of-5. The trade is lower max payout for non-zero downside protection.

The vig math

Round-robins still pay vig on every parlay generated. With 10 parlays at -110 vig each, the cumulative vig burden is significant — typically 12–18% across the structure. Vig isn’t reduced just because you split the bet; it’s spread across more tickets.

This is why round-robins are still -EV by default for most bettors. Splitting variance doesn’t generate edge. It only changes the variance shape.

When round-robins make sense

• You want exposure across a slate without max variance — round-robin a 4–5 game NFL Sunday with 3-leg combinations. Bounded entertainment, better hit rate than a single parlay.
• You believe in 4 of 5 legs strongly but one leg is a flier. A 4-leg round-robin with one extra flier leg gives you protection on the 4 strong legs.
• Bankroll-bounded entertainment. The total stake is fixed, the structure is more forgiving than a single big parlay.

When they don’t

• As a default parlay-replacement. The vig stack is the same; you’re just trading max payout for non-zero return on partial hits.
• For sharp +EV chasing. Every leg is still vig-laden. No structure trick changes the per-leg math.

Sizing tip

A 5-leg round-robin in 3-leg parlays generates 10 tickets. Total stake scales fast. Always check how many tickets the round-robin produces before placing — books will happily show you a “round-robin” UI and let you size up to a much bigger total than you intended.

The combinations follow C(N, K) where N is your leg count and K is the parlay size:

Legs (N)	2-leg	3-leg	4-leg	5-leg
3	3	1	—	—
4	6	4	1	—
5	10	10	5	1
6	15	20	15	6
7	21	35	35	21