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At standard -110 odds you need to win 52.38% of your bets to break even, so a 55% record is only about 2.6 percentage points above that line. Over 100 bets risking $110 to win $100, 55 wins nets $550 on $11,000 wagered, a 5% return. That edge is small enough that luck can hide it for hundreds of bets, or make a bettor with no edge look like they have one.
Where 52.38% comes from
At -110 you risk $110 to win $100. You break even when your wins cover your losses, so wins × $100 = losses × $110. That works out to a win rate of 110 ÷ (110 + 100) = 110 ÷ 210 = 52.38%.
The same formula works for any price: divide what you risk by the total of the risk and the win. Our guide to money lines explains how to read plus and minus prices.
| Price | Risk to win $100 | Break-even win rate |
|---|---|---|
| -105 | $105 | 51.22% |
| -110 | $110 | 52.38% |
| -115 | $115 | 53.49% |
| -120 | $120 | 54.55% |
The extra $10 you have to risk is the book’s cut, often called the vig or juice. If two people bet $110 on opposite sides of a game at -110, the book takes in $220 and pays the winner $210, keeping $10, or about 4.5% of the money bet.
What a 55% win rate is worth
Here’s what different records look like over 100 bets at -110, each risking $110 to win $100, for $11,000 wagered in total.
| Record | Won on winning bets | Lost on losing bets | Net | Return on $11,000 |
|---|---|---|---|---|
| 50–50 | $5,000 | $5,500 | -$500 | -4.55% |
| 52–48 | $5,200 | $5,280 | -$80 | -0.73% |
| 53–47 | $5,300 | $5,170 | +$130 | +1.18% |
| 55–45 | $5,500 | $4,950 | +$550 | +5.00% |
| 58–42 | $5,800 | $4,620 | +$1,180 | +10.73% |
| 60–40 | $6,000 | $4,400 | +$1,600 | +14.55% |
For the 55–45 row, 55 wins × $100 = $5,500 and 45 losses × $110 = $4,950, which leaves $550. Divide that by the $11,000 you risked and you get 5%.
At a true 55%, each bet is worth $5.50 on average: 0.55 × $100 − 0.45 × $110 = $5.50, which is 5% of the $110 you risk. Going from 50–50 to 55–45 turns a $500 loss into a $550 profit. That’s a $1,050 swing from five results out of 100, because each loss that becomes a win is worth $210.
The price you get matters a lot at these margins. The same 55% at -105 returns about 7.4% of the money risked, and at -120 it returns less than 1%. Comparing prices at more than one book helps for that reason, and our guide to choosing an online sportsbook has more on picking where to bet.
Why a 55% bettor can look like a 50% bettor
Even if your true win rate is 55%, your actual record will bounce around it. A quick way to estimate how much is the standard deviation of your number of wins, which is the square root of (bets × win rate × loss rate).
For 100 bets at 55%, that’s √(100 × 0.55 × 0.45) = √24.75, or about 5 wins. By the usual rule of thumb, a true 55% bettor ends up within two standard deviations, anywhere from 45 to 65 wins, roughly 95% of the time.
So 50 wins is about one standard deviation below 55. By the same rule of thumb, landing one standard deviation or more below average happens about one time in six. Worked out exactly, a true 55% bettor wins 50 or fewer of 100 bets about 18% of the time. They win 52 or fewer, which loses money at -110, about 31% of the time.
More bets narrow the range, but slowly.
| Bets | One standard deviation | Two-standard-deviation range for a true 55% bettor |
|---|---|---|
| 100 | 5.0 points | 45.1% to 64.9% |
| 500 | 2.2 points | 50.6% to 59.4% |
| 1,000 | 1.6 points | 51.9% to 58.1% |
| 2,000 | 1.1 points | 52.8% to 57.2% |
Even after 1,000 bets, the bottom of that range sits below the 52.38% break-even line. It takes roughly 1,450 bets before the whole range clears it.
Losing streaks come with it too. Over 500 bets, a true 55% bettor has about a 90% chance of losing six or more in a row at some point.
Why tout records deserve skepticism
Touts, the people and services that sell picks, usually advertise their win rates. The same math works in reverse here. Someone with no edge at all, winning 50% of the time, goes 55–45 or better over 100 picks about 18% of the time. If 100 people each made 100 picks by flipping coins, you’d expect about 18 of them to finish at 55% or better and about 3 at 60% or better, with no skill involved.
Advertised records can also be shaped in ways that are hard to spot:
- A seller can choose when the record starts, for example just after a bad run.
- Picks can be graded at a price that had already moved by the time buyers saw them.
- You only see records from services still selling picks. Any that ran cold may have stopped advertising, which tilts what’s left toward the lucky ones.
Before you trust a record, look for every pick including the losses, the price each one was graded at, a sample in the thousands, and tracking by someone other than the seller from the first pick.
If you pay for picks, the fee comes out of a small edge. Following a true 55% bettor at $110 a bet earns $5.50 per bet on average, so a $100 monthly fee takes about 18 bets a month just to cover.
Sizing your bets
Since any real edge is small and the swings are large, your bet size decides how much a bad run can hurt. One cautious approach is to bet a flat 1% to 2% of your bankroll on each play. With a $1,000 bankroll, that’s $10 to $20 a bet.
Here’s why the size matters. Over 500 bets, a true 55% bettor has about a 37% chance of losing eight in a row at some point. At 5% of your starting bankroll per bet, that streak costs 40% of it. At 1% a bet, it costs 8%.
You may also see the Kelly criterion, a formula that sizes bets from your edge. For a true 55% bettor at -110, it comes to 5.5% of your bankroll per bet. The catch is that nobody knows their true win rate. If yours is really 53%, the Kelly figure drops to about 1.3%, so betting 5.5% would be more than four times too much.
Keep a record of every bet and the price you got. Over a large sample, that record is the only way to learn your real win rate, and the tables above show how many bets that takes. In the US, gambling winnings are taxable income and have to be reported on your tax return.
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Sources
- Break-even, return, standard deviation, binomial probability, losing-streak and Kelly figures: our own calculations
- IRS: Topic no. 419, Gambling income and losses