Odds Boost Calculator

An odds boost is a promotion where a sportsbook increases the profit on a bet by a stated percentage — a “50% profit boost”, say.

The word doing the work is profit. A 50% boost on +100 does not become +200; it becomes +150, because the boost applies to the $100 of winnings and not to the stake you get back.

That makes boosts worth far more on long prices than short ones, and most carry a cap on extra winnings. Past that cap the boost is a flat amount and every further dollar staked is priced at the original odds.

A profit boost multiplies the winnings part of a bet and leaves the returned stake alone. That distinction is the entire calculator. A 50% boost on +100 does not become +200; it becomes +150, because the boost applies to the $100 of profit and not to the $100 you get back.

The practical consequence is that boosts are worth much more on long prices than short ones. At +500 almost all of the return is profit, so a 50% boost moves the price nearly 50%. At −300 most of the return is your own stake coming back, and the same 50% boost barely moves the number. The advertised percentage is identical; the value is not.

Then there is the cap, which is where most of the advertised value quietly disappears. “50% profit boost, max $100 extra winnings” pays the full rate only while your bonus stays under $100. Past that the boost is a flat $100 and the effective rate falls with every extra dollar you stake. Enter the cap above and the headline price is replaced by the one you will actually be paid.

The number worth watching is the break-even rate. It tells you how much of a real edge the boost has bought: if it moves the required win rate from 52.4% to 47.6%, the boost is worth roughly five percentage points of handicapping — which is a lot, and still not a licence to take a bet you would otherwise have passed on.

$100 at +100 with a 50% boost. Profit is normally $100; boosted it is $150, so the price is 2.50 — +150. The break-even rate drops from 50% to 40%.

Now the same 50% boost on −300. Profit goes from $33.33 to $50, and the price moves from 1.333 to 1.50 — −200. Still worth taking, but the break-even rate only falls from 75% to 66.7%, and a market that needs a 75% winner is a market where being wrong is expensive.

Add a $100 cap and stake $500 at +100. Uncapped the boost is worth $250; capped it is worth $100. The effective price falls from +150 to +120, and every extra dollar staked past that point is being priced at the original +100.

Does a boost apply to my stake too?

No. Sportsbooks boost profit only. A 50% boost on a $100 bet at +100 pays $150 profit, not $200 — the returned stake is untouched.

Why is my boost worth less than the advertised percentage?

Two reasons, usually. Short prices are mostly returned stake, so the boost has less to work on. And most boosts cap the extra winnings, at which point staking more stops buying you any more boost at all.

What stake gets the most out of a capped boost?

The stake where the extra profit lands exactly on the cap. Below it you leave boost on the table; above it you are betting the original price on the excess. The calculator flags the point where the cap starts binding.

Is a boosted bet automatically worth taking?

No. A boost improves the price, but the market may have started so far in the book’s favour that even the improved price is bad. Take the effective price from this calculator and put it through the expected value calculator against your own probability.

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