How do you calculate the EV of a profit boost?
Multiply the fair win probability by the boosted decimal odds and subtract 1. If the result is positive, the boost is +EV. Example: fair price +240 means a 29.4% win probability; boosted to +260 pays 3.60x; 0.294 times 3.60 minus 1 is +5.9% EV. The whole calculation takes about ten seconds once you have the fair price.
Here’s the trap first, because it’s the whole reason to learn this: a book boosts a bet to +260 and it looks like a gift. Fair value on that bet is +280. You just took a losing price with a ribbon on it.
“Boost” is the most clickable word in the app, and books know it. Some boosts are real edges handed out as marketing. Plenty are bait, a bumped-up price on a market that was overpriced to begin with. The only way to know which one is in front of you is a ten-second calculation.
The four steps
Step 1: find the fair price. Not the boosted price, not the book’s original price. The market’s best estimate of the true price. The standard way is devigging: take both sides of the market, strip out the book’s built-in margin, and what remains is the market’s honest read of the probability. Why the posted price lies is its own article, but the short version is that every line you see has a fee baked in.
Step 2: apply the boost to your price. A profit boost multiplies the profit, not the total payout. With a 25% boost, +200 becomes +250. With a 50% boost, +200 becomes +300.
Step 3: convert both numbers. The fair price becomes a win probability. The boosted price becomes decimal odds (for positive American odds, divide by 100 and add 1).
Step 4: multiply and compare. EV = fair win probability x boosted decimal odds, minus 1. Positive means the boost beats fair. Negative means skip.
One warning before the examples: the formula is the easy part. The answer is only as good as the fair price you feed it. Garbage fair in, confident garbage out.
A real one, worked
The fair line on a bet is +240. The book boosts it to +260.
- Fair +240 means a win probability of 100 / 340 = 29.4%
- Boosted +260 means decimal odds of 3.60
- EV = 0.294 x 3.60 = 1.059, minus 1 = +5.9%
That’s a real edge, handed over for marketing reasons, and it clears the price test every single time it appears. It will still lose about 7 times in 10. That was priced in. Over volume, each one of these carries about $2.95 of expected value per $50 staked before a single result lands.
The same math catching a fake
Now the trap from the top. Boosted to +260, but fair value is +280.
- Fair +280 means a win probability of 100 / 380 = 26.3%
- Boosted +260 means decimal odds of 3.60
- EV = 0.263 x 3.60 = 0.947, minus 1 = -5.3%
Same boosted price, opposite answer. Looks juicy, still a losing bet, and nothing on the promo screen would ever tell you. The label said boost. The math said no.
The five-second version
Once you’ve done it a few times, the whole check compresses: get the fair price, apply the boost, ask whether the boosted price beats fair. If yes, it’s real. If not, skip it and keep your bankroll for the next one, because books post these daily.
Our boost EV calculator does the arithmetic in one screen: your odds, the boost percent, the fair price in, and the EV and a straight verdict out. Free, no signup.
One more thing worth knowing
The best boost is a percentage boost applied to a bet that’s already +EV on its own, because the boost multiplies an edge that already existed. Those are rare and they’re the closest thing the apps ever hand you to a genuine mistake in your favor. Those are the ones this whole method exists to catch.
This exact check, run against every boost on every book, every day, is what the desk does. The duds get cut and only plays that beat fair make it out, with the math shown. But whether you ever look at that or not, learn the four steps. Nobody who can price a boost in ten seconds ever goes back to trusting the label.
Quick answers
What does a 50% profit boost actually do to the odds?
It boosts the profit portion only, not the whole payout. A +200 bet with a 50% boost pays +300: the original $200 profit on a $100 stake becomes $300. On negative odds it works the same way on the win amount, so -150 with a 50% boost pays what +100 would. That's standard profit-boost mechanics; a few books round or cap payouts, so glance at the terms.
Is every boosted bet +EV?
Not close. A book can take a bad price and boost it to a slightly less bad price. Boosted to +260 sounds great until you learn fair value was +280, at which point you're still on the wrong side of the math. The word 'boost' is marketing. The comparison against fair is the test.
Where do I get the fair price?
Devig the market. Take both sides of the same bet, strip out the book's margin, and what's left is the market's true probability. Free deviggers do this in seconds, or use a sharp low-margin book's price as a shortcut yardstick.
Do minimum odds requirements apply before or after the boost?
On most books, before. A boost with '-200 minimum odds' is checking your pre-boost price, not the boosted one. Read the terms on each promo, because building a slip that fails the fine print is a wasted boost.
Wanna see which boosts cleared the bar today?
The bot checks every boost at every book each morning, posts the ones worth taking with the math shown, and grades everything in public. Watching is free.