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This guide is for bettors who want to understand why the house always has an edge - and which markets have such high overround that you're fighting a losing battle before you even start.
The thing about betting is that it looks like a fair proposition until you actually do the maths. Back both teams in a football match and you'll quickly realize you're losing money no matter who wins. That's overround. The bookmaker structures the odds so that the implied probabilities of all outcomes add up to more than 100%. The difference is their guaranteed profit margin.
I see people on the forum complaining about "bad luck" when they've been betting markets with 110% or 115% overround for six months. That's not bad luck. You're paying a 10-15% tax on every bet. Even if your analysis is perfect, you need to be right significantly more often than the odds suggest just to break even. Most bettors never realize they're fighting a battle they can't win because they never calculated what the bookmaker's edge actually costs them.
How Overround Actually Works
Take a simple football match. Team A vs Team B. In a fair market with no bookmaker margin, if Team A has a 50% chance of winning and Team B has a 50% chance of winning, both teams would be offered at 2.00 odds (evens in fractional).But bookmakers don't offer fair odds. They might offer Team A at 1.90 and Team B at 1.90. Now if you convert those odds to implied probability - which is just 1 divided by the decimal odds - Team A is 52.6% and Team B is 52.6%. Add those together and you get 105.2%. That extra 5.2% is the overround. That's the bookmaker's margin.
What this means in practice is if you bet £100 on Team A and £100 on Team B, you're risking £200 total. If Team A wins, you get back £190. If Team B wins, you get back £190. Either way, you've lost £10. The bookmaker can't lose - they've structured the market so they profit regardless of the outcome.
The overround percentage tells you how much edge the bookmaker has built into the market. A 105% market means they have roughly a 5% edge. A 110% market means they have roughly a 10% edge. The higher the overround, the harder it is for you to win.
Different markets have different overrounds. Main markets like match winner or totals typically have lower overround - maybe 103-107% at sharp books. Niche markets like "total corners in second half" or "first goalscorer" can have overround of 115-130%. Accumulators multiply the overround across every selection, which is why they're almost impossible to beat long-term.
Why Overround Matters More Than Most Bettors Realize
You need to win more than the odds suggest just to break even. If you're betting in a market with 110% overround, you're effectively paying a 10% tax on your action. That means even if you pick winners at exactly the rate the true probabilities suggest, you're losing money.Let's say you find bets you think are 55% to win, and you're getting odds that imply 50% (so 2.00 odds). In a fair market with no overround, you'd make a profit. But in a 110% overround market, those odds aren't actually 2.00 - they're more like 1.85 once you account for the margin. Now your 55% win rate isn't enough. You need to win 58-59% just to break even.
This is why sharp bettors obsess over finding the lowest overround. The difference between betting at a book with 103% overround versus 110% overround is massive over thousands of bets. It's the difference between profitable and unprofitable even with the exact same selection skill.
Recreational bettors ignore this completely. They'll bet wherever is convenient or wherever has the best promotional offer, not realizing they're paying 5-7% more in margin than they would at a sharp book. Over a year of betting, that's the difference between winning and losing.
The Markets With the Worst Overround
Not all markets are created equal. Some have such high overround that beating them long-term is nearly impossible.First goalscorer markets are brutal. The overround is often 120-140% because there are so many outcomes. The bookmaker lists every player who might score, prices them all individually, and builds in massive margin. You're fighting a 20-40% edge before you even start. Even if you correctly identify that a certain striker is underpriced, the margin is so high that you need to be spectacularly right to make money.
Correct score markets in football are even worse. There are dozens of possible scorelines. The bookmaker prices each one and the total overround can be 130-150% or higher. This is why correct score bets feel like lottery tickets - the odds look massive but they're actually terrible value once you account for the bookmaker's edge.
Accumulators multiply the overround across each selection. If you're betting a four-fold accumulator and each individual bet has 105% overround, the total overround on your accumulator is roughly 1.05^4 = 1.216, or 121.6%. You're paying a 21.6% margin. The bookmaker loves accumulators because they compound their edge.
Novelty markets and specials have ridiculous overround. "Next manager to be sacked" or "Player to be booked and team to win" - these markets often have 125-140% overround because they're low-volume markets where the bookmaker needs to protect themselves. The odds look interesting but they're horrific value.
Live betting markets during the match have higher overround than pre-match. The bookmaker needs to adjust odds in real-time and they protect themselves with wider margins. A market that was 105% pre-match might be 115-120% in-play. The odds move fast, the margin is higher, and you're fighting a much bigger edge.
The Markets With the Best Overround
Sharp books on high-volume markets have the lowest overround. Main markets on Premier League or NFL - match winner, totals, spreads - will often be 102-105% overround at sharp bookmakers. These are the most efficient markets because they get the most action and the most informed money.Asian handicap markets are usually lower margin than European odds. The structure of Asian handicaps means the bookmaker can offer tighter prices. You'll often find 101-103% overround on Asian handicap lines at sharp books, which is about as low as it gets in sports betting.
Exchange betting removes the bookmaker entirely. On Betfair or similar exchanges, you're betting against other punters, not against the house. The overround is determined by what other bettors are willing to offer, and it's often 100-102%. The exchange takes a commission on winnings instead of building in margin. This is why professional bettors prefer exchanges when possible.
American sports at reduced-juice sportsbooks can get down to 102-104% overround. Books like Pinnacle that cater to sharp action offer NFL and NBA lines at -105/-105 instead of the standard -110/-110. That reduces the overround from about 104.8% to 102.4%. Doesn't sound like much but over thousands of bets it's the difference between winning and losing.
Early markets before the sharp money comes in sometimes have lower overround. When a book first posts lines for next week's matches, they're not sure how much action each side will get. They might post with tighter margins to attract two-way action. Once the market gets bet into and they see which side the sharp money likes, they'll widen the margin to protect themselves. But that early window can have lower overround if you're quick.
How to Calculate Overround Yourself
You need to do this manually because bookmakers won't tell you. Take every possible outcome in the market, convert the odds to implied probability, and add them up.For decimal odds, the formula is simple: Implied probability = 1 / decimal odds. So if Team A is 2.00, that's 1/2.00 = 0.50 = 50%. If Team B is 1.90, that's 1/1.90 = 0.526 = 52.6%.
For American odds, it's slightly more complicated. For negative odds (favorites): Implied probability = (absolute value of odds) / (absolute value of odds + 100). So -110 is 110/(110+100) = 52.4%. For positive odds (underdogs): Implied probability = 100 / (odds + 100). So +150 is 100/(150+100) = 40%.
For fractional odds, convert them to decimal first or use: Implied probability = denominator / (numerator + denominator). So 5/1 is 1/(5+1) = 16.7%.
Once you have the implied probabilities for every outcome, add them all up. If the total is more than 100%, the difference is the overround. A market that adds up to 108% has 8% overround.
Three-way markets like football match betting (home/draw/away) will have higher overround than two-way markets just because there are more outcomes to price. A typical Premier League match might be 105-107% overround. You calculate it the same way - convert all three outcomes to implied probability and add them up.
Why Some Books Have Higher Overround Than Others
Sharp books that take large bets have lower overround. Pinnacle, Betfair, Asian bookmakers - these books cater to winning players. They can't build in huge margins because sharp bettors would just arbitrage them or find better prices elsewhere. They make money on volume and by adjusting their lines based on where the smart money goes.Recreational books that limit winners have higher overround. High street bookmakers, most European books, books that advertise heavily to casual bettors - they build in wider margins because they can. Their customers aren't shopping for the best price, they're betting for entertainment. These books will happily offer 110-115% overround on main markets because their customer base doesn't care.
The business model determines the margin. Sharp books are market-makers - they want to set accurate lines and make money on the overround while taking bets from everyone. Recreational books are risk managers - they want to limit sharp action and extract maximum value from casual bettors. The recreational books need higher margins because they're not getting the same volume of two-way action.
Regulated markets often have worse overround. In jurisdictions with heavy gambling taxes and regulations, bookmakers pass those costs on to bettors through wider margins. A book operating in the UK with 15% tax on gross gaming revenue needs to extract more from each bet than a book operating offshore with minimal tax. This is why the same match might be 105% overround at an Asian book and 110% overround at a UK high street book.
How Market Efficiency Relates to Overround
Low overround doesn't mean the market is easy to beat. Sharp books with 102% overround are actually harder to beat than recreational books with 110% overround because the lines are more accurate.Market efficiency means the odds correctly reflect the true probabilities. An efficient market is one where you can't consistently find mispricings. The Premier League match winner market is extremely efficient - millions of pounds get bet, sharp bettors analyze it thoroughly, the bookmakers adjust quickly. Finding value is hard even though the overround might only be 105%.
Inefficient markets have higher overround but worse pricing. A niche market like Icelandic second division football might have 115% overround but the odds are also less accurate because nobody's analyzing it properly. If you do your homework, you might find mispricings that overcome the high margin.
You need to consider both factors. The perfect market to bet is one with low overround AND pricing errors you can exploit. That's rare. Usually you're choosing between efficient markets with low margin (hard to find edges) or inefficient markets with high margin (edges exist but you're paying more to exploit them).
The most profitable bettors focus on inefficient markets with low overround. Asian handicap markets on less popular leagues, early lines before the sharp money comes in, niche sports that bookmakers don't specialize in - these are the sweet spots where you can find both reasonable margins and exploitable pricing errors.
The Overround Trap in Accumulators
Bookmakers love accumulators because the margins compound. People don't realize how bad the overround gets when you combine multiple selections.A single bet at 105% overround costs you 5%. A double at 105% per selection compounds to 1.05 x 1.05 = 110.25% overround. A four-fold is 1.05^4 = 121.55%. A ten-fold is 1.05^10 = 162.89%. You're paying a 62.89% margin on a ten-fold accumulator even if each individual bet only has 5% overround.
This is why accumulators feel exciting but destroy bankrolls. The odds look massive - 50/1, 100/1 - but the true fair odds are probably 80/1 or 150/1 once you account for the compounded margin. You're getting horrific value.
Acca insurance and bonus offers don't fix this. Some bookmakers offer "get your money back if one leg loses" or "10% bonus on four-folds." That looks generous but it doesn't come close to compensating for the 15-20% margin you're paying on the accumulator itself. The promotions are designed to make you feel like you're getting value when you're still getting destroyed by overround.
Single bets with low overround will always outperform accumulators mathematically. If you want to bet multiple matches, bet them as singles instead of combining them into an accumulator. You'll get better value even though the potential payout is lower.
What You Can Actually Do About Overround
You can't eliminate it but you can minimize it. The first step is shopping for the best odds. Different bookmakers price the same market differently. One book might have Team A at 1.85 while another has them at 1.90. That's a 2.6% difference in implied probability. Over hundreds of bets, that matters.Use an odds comparison site. OddsPortal, OddsChecker, whatever works in your jurisdiction. Check multiple bookmakers before placing a bet. Don't just bet at one book out of convenience or loyalty. The best odds might be somewhere else.
Focus on markets with low overround. Main markets on popular sports are your best bet. Premier League match winner, NFL totals, NBA spreads - these markets have the tightest margins. Avoid niche markets and exotics unless you have a specific edge that overcomes the high overround.
Consider using betting exchanges where possible. Betfair, Smarkets, Betdaq - these exchanges have dramatically lower overround than traditional bookmakers. You pay commission on winnings instead of built-in margin. For serious bettors, this is often the only way to overcome the overround problem long-term.
Reduce bet frequency and increase selectivity. If you're betting every match because you enjoy the action, you're paying the overround hundreds of times per season. If you only bet when you have a genuine edge, you're paying it far less often. Quality over quantity isn't just good advice, it's mathematically necessary when fighting overround.
Track your closing line value. If you're consistently betting odds that move in your favor before kickoff, you're beating the market even if you don't win every bet. This is a better indicator of skill than short-term profit because it shows you're getting better than fair odds regardless of the overround.
When High Overround Markets Are Still Worth Betting
Sometimes you have such a strong edge that you can overcome even terrible margins. If you've identified a correct score that should be 50/1 and the bookmaker is offering 80/1 even in a market with 140% overround, there's still value.Novelty markets with information advantages can be profitable. If you know something the bookmaker doesn't - inside information on team selection, injury news that hasn't been priced in, managerial decisions that aren't public yet - you might be able to overcome 120% overround with your information edge.
But this is rare. For most bettors, high overround markets are traps. You might win occasionally but the margin is too high to beat consistently. Don't convince yourself you're the exception unless you have data proving it.
The correct approach is to understand the overround of every market you bet, factor it into your edge calculation, and avoid markets where the margin is so high that you'd need an unrealistic edge to profit.
The Overround Difference Between European and Asian Books
European bookmakers typically have higher overround. Main football markets at European books are often 105-108%. Some high street bookmakers go even higher - 110-112% on main markets. They cater to recreational bettors who care more about convenience and brand recognition than finding the best price.Asian bookmakers and betting sites have lower overround. Markets at Pinnacle, SBOBet, IBC, or similar sharp books are usually 102-105%. Asian handicap markets specifically are often 101-103%. These books cater to high-volume sharp bettors who shop for the best prices. They can't get away with wide margins because their customer base would go elsewhere.
The difference compounds over time. Betting 100 times at 108% overround versus 103% overround doesn't sound dramatic. But that's a 5% difference on every bet. Over those 100 bets, you're paying roughly £5,000 more in margin at the high overround book (assuming £1,000 average stake). That's the difference between a profitable year and a losing one for many bettors.
If you're serious about betting, you need access to low-overround bookmakers. This might mean using Asian books, offshore sites, or betting exchanges. It might mean dealing with less convenient payment methods or withdrawal processes. That inconvenience is worth it. The difference in overround is massive.
Regulatory Impact on Overround
Regulated markets often have worse overround because of tax structures. The UK has a 15% tax on bookmaker gross gaming revenue. Italy taxes turnover. France has advertising restrictions that increase customer acquisition costs. Bookmakers pass these costs on through wider margins.This creates a two-tier system. Recreational bettors use regulated books because they're accessible, advertised, and trustworthy. Professional bettors use offshore or Asian books because the margins are lower. The regulations designed to protect consumers actually hurt them by increasing the overround they pay.
Some jurisdictions allow lower margins through exchange betting. The UK permits Betfair and other exchanges, which gives serious bettors a low-overround option. Other countries ban exchanges or restrict them, forcing everyone into high-overround bookmaker markets.
Common Misconceptions About Overround
People think "the odds are good" without calculating the overround. You see odds of 3.00 on an outcome and think "that's great value." But if the market has 120% overround, those odds might represent a 40% true probability priced at 33%. That's not value, that's terrible.Bettors assume all bookmakers are roughly the same. They're not. The difference between betting at Bet365 versus Pinnacle on the same market can be 3-5% in overround. That difference destroys your edge over time.
People think promotional offers overcome bad overround. Bookmakers offer free bets, odds boosts, acca insurance. These promotions look generous but they rarely compensate for the high base margins. A 10% acca boost on a market with 120% overround still leaves you paying 108% after the boost. You're still getting destroyed.
Bettors believe winning percentage is all that matters. You can win 55% of your bets and lose money if you're betting in markets with 110% overround. You need to win significantly more than the implied probability suggests, which means your win percentage needs to be much higher than you think.
How to Track Whether Overround Is Killing You
Calculate your average overround across all bets. Take a sample of your recent bets, work out the overround for each market, and average them. If you're consistently betting markets with 110%+ overround, you're making your job much harder than it needs to be.Track your results by overround bracket. Separate your bets into low overround (under 105%), medium overround (105-110%), and high overround (over 110%). Compare your results in each bracket. Most bettors will find they're profitable in low overround markets and unprofitable in high overround markets even though they think they're finding value everywhere.
Compare your actual ROI to your expected ROI. If your selections are winning at 53% but your ROI is negative, the overround is killing you. Work backward from your win rate to figure out what overround you can afford. If you're winning 53% at average odds of 2.00, you need to be betting in markets below 106% overround to be profitable.
Check where you're placing most bets. If 70% of your action is on accumulators and exotic markets, you're paying massive overround and probably losing money even if you're a good handicapper. Shift your volume to low-overround main markets and your results will improve.
FAQ
How much overround is acceptable for a serious bettor?Ideally under 105% for main markets. Professional bettors try to stay below 103-104% by using sharp bookmakers and exchanges. Recreational bettors betting for entertainment might be fine with 107-108% if they're selective about volume. Above 110% overround, you need an unrealistic edge to profit long-term.
Can I beat high overround markets with better analysis?
Only if you have a massive information or analytical edge. A market with 120% overround means you're paying 20% more than fair value. You'd need to find mispricings of 25-30% just to break even. That's possible in niche markets where the bookmaker is guessing, but it's rare. Focus on low overround markets where smaller edges are sufficient to profit.
Why do accumulators have such bad overround?
Because the margin compounds across each selection. A four-fold accumulator with 105% overround per leg has roughly 121% total overround. The bookmaker's edge multiplies with each additional selection. This is why accumulators are extremely profitable for bookmakers and extremely unprofitable for bettors despite the exciting payouts.
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