Parlay Maths: How Legs Multiply and Why One Miss Sinks the Slip

A parlay is one bet built from several: two or more selections on a single slip, with their odds multiplied together. The payout grows fast, which is the whole appeal, but every leg has to win, so a single miss loses the lot. Parlays go by other names too, combo, accumulator and multi, and the bet menu of the BTI book on MERRYPH’s Sports tab includes a Combo entry. Before building one, it helps to see what the multiplication does to both the price and the chance.

How a parlay pays: multiply the legs

Every leg below is priced at 1.90, a common price on a near-even pick.

The return grows by 1.9 each time while the chance halves each time. That gap is the cost.

Parlay betting and the margin that stacks

A 1.90 price on a true coin flip pays back 95 centavos per peso on average, so the book keeps 5 percent. Parlay betting multiplies that too.

1. One leg: you get back about 95 percent of stakes over time.
2. Three legs: 0.95 × 0.95 × 0.95, about 85.7 percent, so the cost rises to roughly 14 percent.
3. Five legs: about 77.4 percent back, a cost near 23 percent.
4. The same five picks as singles would still cost only 5 percent each.

When a single beats a parlay

1. You have one strong opinion: bet it alone instead of diluting it with weaker legs.
2. The legs are linked: a team winning and the total going over often move together, and many books refuse those combinations anyway.
3. You are betting most of a weekly budget: a parlay’s long losing runs suit only small, fixed stakes.
4. You want to learn: singles show you which of your reads actually work; parlays hide it.

If you liked the size of a parlay’s payout but not its odds of landing, a two-leg parlay at a small stake is the gentlest version.

Building a two-leg parlay, step by step

1. Pick two selections from different events so one result does not drag the other.
2. Multiply the prices: 1.85 × 2.10 = 3.885.
3. Multiply by the stake: ₱150 × 3.885 returns ₱582.75 if both win.
4. Compare with two ₱75 singles at the same prices: ₱138.75 plus ₱157.50 if both win, and something back if only one does.

Void legs, pushes and partial results

Problem: one NBA game in your slip is postponed. Fix: most books drop the void leg and settle the rest at the remaining odds; read the settlement rules for the exact treatment.

Problem: an esports handicap lands exactly on the line on a whole-number handicap. Fix: that leg pushes and usually counts at odds of 1.00, cutting the combined price.

For the legs themselves, see the NBA spread and total markets and esports map handicaps. Price formats are explained on the decimal odds and margin page, and the full list of sports is on the sportsbook hub.