Expected Value, often called EV, is a simple but powerful concept: it’s the average result you’d expect from a bet if you could replay it over and over.

In betting terms, EV measures the gap between the true probability of an outcome and the odds offered by the sportsbook. In other words, it tells you whether the odds are in your favor or not.

If a bet has positive EV (+EV), it means you stand to gain money on average in the long run. If it has negative EV (-EV), you’re likely to lose money over time.

Think of EV as the guide that helps you decide if a wager is worth the risk – it’s not about guaranteed wins today, but about making smart bets that pay off over many plays.

To illustrate, imagine a simple game: You bet $1 on a coin flip. If it’s heads, you win $2; if tails, you get nothing.

The coin is fair (50/50 chance on each side). Half the time you win $2, half the time you lose $1, so what’s your expected result per flip?

It would be: 0.5 × $2 (win) – 0.5 × $1 (loss) = $1 – $0.50 = $0.50. On average, you’d make 50 cents per flip. That 50 cents is the expected value of the bet.

A positive EV like this means that if you played this game repeatedly, you’d come out ahead. If the payouts were worse (say win $1 for heads, lose $1 for tails), the EV would be zero (break-even). If the payouts were even worse (win $0.80 for heads), the EV becomes negative, meaning you’d expect to lose money each flip.

Sports bets work the same way: each wager has an expected value based on how often you’ll win and how much you win when you do.

Why EV Matters for Long-Term Profitability

Most casual bettors focus only on picking winners – they bet on the team they think will win tonight’s game. While picking winners feels good, it’s not enough to make a profit if the price (odds) is bad.

This is where EV becomes crucial. If you consistently take bets with positive expected value, you give yourself an edge that, over time, can make you profitable.

Think of it this way: winning 50% of your bets isn’t profitable if you’re always laying -110 odds (because the sportsbook’s cut, or “juice,” means you need about 52.4% wins just to break even). The only way to get ahead is to find bets where the odds are skewed in your favor – those are +EV bets.

Expected value is what separates a savvy, long-term winner from someone who might get lucky now and then but loses over the long haul.

Even sportsbooks know this; they thrive because most bettors take negative EV bets without realizing it. Not considering EV in your wagers practically “assures long-term failure”.

On the flip side, consistently betting with positive EV tilts the math in your favor, so over many bets, you’re more likely to come out ahead.

Importantly, this doesn’t mean you win every bet – you will still have losing nights. But with +EV, your wins should outweigh your losses in the long run.

It’s a bit like a casino running a game: they might lose a few rounds, but because the game has a house edge (positive EV for them), they profit after enough rounds.

By embracing EV, you become the house in a sense, making sure the odds are on your side whenever possible.

How to Calculate Expected Value

Don’t worry – you don’t need advanced math to figure out expected value. The formula for EV is straightforward:

EV = (Probability of Winning) × (Amount Won per Win) – (Probability of Losing) × (Amount Lost per Loss)

Each bet has two main outcomes: you either win or lose. So to gauge the EV, you multiply the chance of winning by the profit you’d make if you win, then subtract the chance of losing multiplied by the amount you’d lose.

The result tells you the average profit (or loss) per bet if you could make that same bet many times. A positive number means a profitable bet in the long run; a negative number means a losing proposition.

Let’s break it down with a sports example for clarity. Say there’s an NFL underdog listed at +150 odds, and you believe this underdog has a 45% chance to win the game. If you bet $20, a win at +150 yields a $30 profit (since +150 means you win $1.50 for every $1 bet, $20×1.5 = $30). The chance of losing is 55% (the rest of the 100%). Now plug these into the formula:

  • Probability of winning = 0.45 (45%)

  • Amount won if win = $30

  • Probability of losing = 0.55 (55%)

  • Amount lost if lose = $20

Now, EV = 0.45 × $30 – 0.55 × $20 = $13.50 – $11.00 = +$2.50 . An expected value of +$2.50 means on average, you would profit $2.50 for every $20 wagered with these conditions. This is a +EV bet (specifically, about a 12.5% ROI on your $20). If you could make a similar bet 100 times, you’d expect to be about $250 ahead in total (though in reality, the distribution of wins and losses will vary).

Conversely, if the odds were worse relative to your 45% estimation – say the underdog was only +120 (meaning a $20 bet wins $24 profit) – let’s check the EV: win probability 0.45 × $24 = $10.80, loss probability 0.55 × $20 = $11.00, EV = $10.80 – $11.00 = –$0.20. That would be a negative EV (–$0.20 on average per $20 bet). Over time, such a bet would bleed money.

In summary, EV math tells you the quality of a bet in dollar terms: a positive number is good (take that bet every time you can!), zero means break-even, and negative means in the long run you’re paying to play, which is not a winning strategy.

Examples of +EV and -EV Bets (Moneylines and Spreads)

Example 1: A +EV Moneyline Bet – Imagine an NBA game where the underdog team is listed at +200 (which implies roughly a 33% chance to win). You’ve done your homework and feel this underdog actually has about a 40% chance to win – maybe the favorite’s star player is resting, and the market hasn’t fully adjusted.

Your friend, a casual bettor, only sees that the underdog will “probably lose.” But you see value. The sportsbook is paying 2-to-1 on a team that you believe has a 40% shot. If you’re right about the 40%, this bet is highly +EV. For a $100 wager: 0.40 × $200 (profit) – 0.60 × $100 (loss) = $80 – $60 = +$20 expected value.

In other words, even though you expect to lose the bet 60% of the time, the payout is so rewarding in the 40% of wins that you’d net an average of $20 per bet over the long run.

This is a textbook positive EV scenario – the kind sharp bettors love. In fact, if the “true odds” of the underdog are shorter (i.e., better) than the odds you’re being offered, you’ve found a value bet. Here, a true win chance of 40% would correspond to fair odds of +150, but you’re getting +200, which is a great deal.

Example 2: A -EV Point Spread Bet – Now let’s look at a point spread, which many casual bettors enjoy.

Say Team A is a 7-point favorite at -110 odds (you must bet $110 to win $100) on the point spread. Most people might think, “Team A is strong; they should cover the spread easily.” But we need to check the value.

The -110 odds carry an implied break-even win rate of about 52.4% (you must win ~52.4% of bets at -110 to break even due to the juice). Suppose after analyzing the matchup, you estimate Team A has about a 50% chance to cover the 7-point spread (maybe the team often wins but calls off the dogs and doesn’t run up the score).

That means even though you think it’s an even toss-up, the odds require above 52% to profit – your prediction (50%) is below that. This is a negative EV bet.

If you force this bet, you’re essentially expecting to lose money in the long run because you’re taking worse than fair odds.

Numerically, for a $110 bet: 0.50 × $100 – 0.50 × $110 = $50 – $55 = –$5. An average loss of $5 per bet is a losing proposition.

A value-focused bettor would skip this wager because the line doesn’t offer an edge. This example shows that even a team that’s likely to win can be a bad bet if the price is too steep.

Many bettors fall into the trap of laying heavy odds on a favorite (or giving up points on a spread) without realizing the expected value is negative – the team wins the game, but not often enough against the spread or not by enough to justify the cost.

How to Spot Value: Estimating Probability vs. Implied Odds

So, how do you know if a betting line offers value? It comes down to comparing your own estimated win probability for a bet to the implied probability of the odds. Every set of odds corresponds to a percentage chance – this is the sportsbook telling you how often the outcome needs to occur for the bet to break even.

For example, +100 odds mean 50% implied chance, +200 means about 33%, +150 about 40%, -150 about 60%, and so on. To find the implied probability, you can convert the odds or use readily available calculators.

But a quick rule of thumb: positive odds (e.g. +150) = profit / (profit + stake), so +150 = 150/(150+100) = 0.60 (which is the loss probability; subtract from 1 to get win probability ~0.40 or 40%).

Negative odds (e.g., 150) = stake / (stake + profit), so -150 = 150/(150+100) ≈ 0.60 (meaning 60% implied win chance).

You don’t need to memorize formulas – the key is understanding that odds tell you what percentage of the time you must win to not lose money.

Once you have the implied probability from the odds, compare it to your probability estimate for that outcome.

If you genuinely believe an outcome will happen more often than the odds imply, you’ve found a potential +EV bet.

If you think it will happen less often than implied, it’s a -EV bet to avoid.

This is the heart of value betting.

As an example, let’s revisit the scenario from before: Sportsbook gives an underdog at +150 (implied ~40%). After your analysis, you think that the underdog has a 45% chance of winning. Your estimate (45%) is higher than the book’s number (40%), which indicates a positive gap – the odds are in your favor.

Indeed, seeing +150 when true chance is 45% “indicates value on your side”. You would expect to profit in the long run by betting on that underdog.

On the other hand, if a team is -200 (implied 66.7%) but you believe they win that game only about 60% of the time, the odds are not paying you enough for the risk – that’s a bad value bet (you’d be laying -EV odds).

In practice, making these judgments requires research, knowledge, and sometimes statistical models. You won’t know the exact true probability (nobody does), but the more accurately you can estimate it, the better you can sniff out value.

Successful bettors use everything at their disposal – stats, injuries, situational factors – to arrive at a solid estimate of a team’s chances, then compare that to the line. When the difference is big enough in their favor, they pounce on the bet.

One thing to remember: even a value bet can lose, and a -EV bet can win on a given day.

EV is about the long term. Think of each bet like a single roll of a loaded die – a +EV bettor has loaded the dice slightly in their favor. In any one roll, anything can happen, but over hundreds of rolls, the favorable odds shine through.

That’s why professionals often say “trust the process” and take many bets; they know it takes a lot of trials for the expected edge to manifest.

It’s not uncommon for sharp bettors to place hundreds of wagers a month so that their 1-5% edges compound into meaningful profits.

If you have an edge, the more you repeat it, the closer you get to the expected outcome.

Meanwhile, if you consistently bet without an edge (negative EV), more bets just dig you a deeper hole.

Shifting Your Mindset: From Chasing Wins to Chasing Value

Understanding expected value might feel like a lightbulb moment – suddenly, you’re not just looking for who will win, but for which bets are worth it. This mindset shift is what separates “gamblers” from smart bettors. Instead of asking “Which team is a sure win?”, start asking “Where are the odds in my favor?”. Here are some friendly tips to help you start thinking like a value-driven bettor:

  • Don’t Bet Just Because You “Feel” a Winner: It’s tempting to back the team you’re convinced will win tonight, but if the price is bad (e.g., a huge favorite with tiny payout), it’s not a smart bet. A heavy favorite might win the game, but the odds might be so steep that the bet has negative EV (you risk too much for too little return). Remember, a winning bet can still be a poor-value bet! Smart bettors would rather take a calculated risk on an underdog at the right price than a favorite at terrible odds. +EV bettors don’t necessarily wager on who they expect to win, but on where the odds misprice an outcome – sometimes that even means betting on the team you expect to lose because the payout is worth it.

  • Leave Your Heart Out of It: Betting with your heart (for your favorite team or the popular hometown hero) can cloud your objectivity. Sure, it’s fun, but it’s not how you find value. The odds on popular teams are often inflated (because so many fans bet them), which can make them -EV bets. As a savvy friend might warn you: don’t just follow the crowd. If everyone is overhyping one side, the value might lie with the other side. The goal is to bet with your head, not your heart. For example, if the Dallas Cowboys (a hugely popular team) are heavily favored, the line might be too rich to bet on them – the value could be in betting their lesser-known opponent if the public has pushed the odds to an extreme. +EV bettors treat their favorite team as the one offering the best value, not necessarily the one they emotionally want to win.

  • Think Long Term – Embrace the Grind: Shifting to a value mindset means accepting that you won’t win every bet, and that’s okay. You might lose a few bets in a row, even when each was a good value decision. This is normal because of variance (random chance). The idea is that over dozens or hundreds of bets, the positive EV strategy will yield profits. It’s just like a casino expecting to make money over a month, not on every single hand dealt. So, don’t get discouraged by a short losing streak if you know you made a smart +EV bet. Conversely, don’t get overly excited about a lucky win on a bad bet – one lucky hit doesn’t change the fact that it was a poor bet. Focus on making good decisions repeatedly. Over time, those small edges add up. Many sharp bettors require a large sample (hundreds of bets and several months) to see their advantage play out. Patience and consistency are your friends.

By adopting these approaches, you start betting like an investor rather than a gambler. Each wager is evaluated on its merit (expected value), not just on gut feel.

You’ll find that this makes the betting experience more strategic and, in the long run, more rewarding. It can take the pressure off individual bets – you don’t have to sweat every single result as a referendum on your skill. Instead, you trust that if you keep finding +EV spots, the numbers will work out in your favor.

Conclusion: Be Your Own “House”

At the end of the day, expected value is the sports bettor’s secret weapon. It’s the concept that turns betting from pure speculation into a calculated strategy.

By understanding EV, you’re essentially doing what the sportsbooks do: evaluating odds and only taking a bet when the payout justifies the risk. Think of yourself as running your own little sportsbook – you “offer action” on bets that benefit you.

This doesn’t mean you’ll win every time (even the best bettors hit only ~55% of their bets), but it means you’re making informed choices grounded in math and logic.

So next time you’re browsing the lines, pause and ask: “Is this a good value, or am I just guessing?” If you start to choose bets because the odds are in your favor (and not solely because you feel a winner), you’re on the path to being a sharper bettor. It might feel different from the usual adrenaline-chasing mindset, but it’s a change that can turn betting into a more sustainable hobby (or even a side profit source).

The fun part is, once you get the hang of spotting +EV bets, you’ll watch games with extra confidence – even when you’re on an underdog or an unpopular side, you know you got the best of the number. Over the long run, that makes all the difference.

In summary, betting with expected value in mind is about betting smarter, not harder. It’s the key trait that separates the long-term winners from the rest.

You don’t need to be a math whiz or a professional gambler to apply it; you just need the willingness to look beyond today’s win-loss and focus on the bigger picture.

With a bit of practice, you’ll start seeing sports bets the way a savvy friend or pro would – not as “locks” or “upsets,” but as good bets or bad bets based on value. And when you consistently make good bets, the winnings take care of themselves.

Happy value hunting, and may the odds be ever in your favor – at least, more in your favor than in the house’s!