Odds boosts explained

An odds boost is the one sportsbook promotion that changes the thing that matters most: the price. A good one can push a bet from a small expected loss to a small expected gain. A weak one dresses up a favourite at a price that was never generous. This guide shows the three types of boosts, how to value each with a few lines of arithmetic, and the terms that decide whether a boost is worth your time.

Three kinds of boost

LeoVegas and Stake list odds boosts among their standing promotions; 20Bet and Oxibet run parlay boosts. The live list is on the boosts page.

Valuing a price boost

Start with the unboosted price and its margin. On a typical market, the true chance of a selection at decimal odds D is roughly the payout share divided by D. With a 95.45% payout (a -110 two-way line):

• True chance at 2.50 = 0.9545 / 2.50 = 38.18%
• Expected return at 2.50 = 0.3818 x 2.50 = 0.9545, a 4.55% loss
• Expected return at 3.00 = 0.3818 x 3.00 = 1.1454, a 14.54% gain

The same maths flags a weak boost. A favourite boosted from 1.50 to 1.60 on a market with a 6% margin: true chance about 0.94 / 1.50 = 62.7%, expected return at 1.60 = 0.627 x 1.60 = 1.003. Close to break-even, nothing more.

Valuing a profit boost

A profit boost multiplies only the winnings.

• Boosted odds = 1 + (D - 1) x (1 + boost)

Check on 2.50 with 50%: profit 1.50 x 1.5 = 2.25, plus the stake = 3.25.

Profit boosts are worth more at longer odds, because there is more profit to multiply. A 50% boost on 1.50 adds 0.25 to the odds; on 4.00 it adds 1.50.

Parlay boosts

Parlay boosts pay a percentage on top of winning parlays, usually rising with leg count, and usually with a minimum price per leg (often 1.20 or more). They help, but the parlay's compounded margin starts high. On four legs at -110, the built-in edge is about 17%; a 10% profit boost brings expected return from 83.02% to about 90.7%. Still negative. The parlays guide shows the full table, and the parlay calculator applies a boost percentage for you.

The terms that decide the value

• Maximum stake. Most boosts cap the stake. The value of a boost is the improvement times the capped stake, so a strong boost on a tiny stake is still small money.
• Paid as cash or bonus. Some books pay the boosted part of the winnings as bonus bets. Value those with the free bets guide.
• Market restrictions. Boosts often apply to one selection or one market. Check whether overtime is included; see moneyline, spread and totals.
• One per customer, opt-in. Many boosts need an opt-in before the bet. A bet placed without it is settled at normal odds.
• Expiry. A boost listed for tonight's game ends at puck drop.

Boosts against other promotions

Using the same 95.45%-payout market, here is roughly what each promotion adds per C$25, illustrative and before any max-stake limits:

Check on the profit boost: true chance 38.18%; expected return at 3.25 = 0.3818 x 3.25 = 1.2409; at 2.50 it was 0.9545; the difference, 0.2864, times C$25 is about C$7.16. The free bet row comes from the free bets guide table (63.6% of face value at 3.00). Parlay boosts add the least, because they start from the weakest base.

Spotting a real boost

Compare the boosted price with the same market elsewhere. If two other books already offer 2.90 on what one book "boosts" from 2.50 to 3.00, the real boost is small. That is one reason to hold accounts at more than one book, covered in how to choose a sportsbook. Convert prices with the odds converter and check the margin with the method in the bookmaker margin guide.

Keep it in budget

A boost changes the price of a bet you were going to make; it is not a reason to bet more often. The Lower-Risk Gambling Guidelines suggest gambling on no more than four days a month and no more than 1% of household income. Our bankroll management guide sets stakes from that budget, and responsible gambling lists the helpline for your province.