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Understanding Breakeven Percentage: A Guide for Serious Bettors

Updated: Nov 1

If you're taking the step from recreational bettor to sharp, breakeven percentage is the first number you should know for any bet. This guide will provide clear definitions, correct formulas, worked examples, common traps, and quick mental math so you can use it today.


TL;DR

  • Breakeven % = the win rate you must hit at a given price to not lose money long term.

  • If your true win probability > breakeven %, the bet has expected value and you'll win in the long run.

  • Know this for every bet before you place it. Everything else builds on this.


What “Breakeven” Really Means

Imagine you place the same bet thousands of times at the same price. If your profits equal your losses on average, you’re breaking even. The breakeven percentage is the minimum win rate that makes this true.


This is price-dependent—not all 55% win rates are created equal. A 55% record at -200 is losing. A 55% record at +120 is crushing. Price sets the target.


Converting From American Odds to Breakeven Percentage

  • For favorites (negative odds like -110):

  • Breakeven % = |Odds| / (|Odds| + 100)

  • Example: −110 ⇒ 110 / (110 + 100) = 0.5238 = 52.38%

  • If your true win probability is above 52.38%, you have +EV and will profit in the long run.

  • For underdogs (positive odds like +150):

  • Breakeven % = 100 / (Odds + 100)

  • Example: +150 ⇒ 100 / (150 + 100) = 0.40 = 40%

  • If your true win probability is above 40%, you have +EV and will profit in the long run.


Quick Reference Table (Prices That Sharps Memorize)

American

Breakeven %

American

Breakeven %

-300

75.0%

+300

25.0%

-250

71.43%

+250

28.57%

-200

66.67%

+200

33.33%

-150

60.0%

+150

40.0%

-140

58.33%

+140

41.67%

-130

56.52%

+130

43.48%

-120

54.55%

+120

45.45%

-110

52.38%

+110

47.62%

Rule of thumb near even money: Every ~10 cents changes breakeven by ~2% (a touch less as prices get farther).


Does Breakeven Change When You Account for Vig?

Short answer: No. Convert the odds you get on the bet into probability, and that's your breakeven percentage. You need to beat the vig to profit.


Long answer:

  • Breakeven % at your ticket price tells you your hurdle.

  • Sportsbooks have their estimate of the "true probability," then add vig on top of it.

  • Removing vig estimates the "true probability" according to the book.


Comparing your estimate of the "true probability" to your ticket’s breakeven % tells you if you have +EV.


Compare the vig-free probability to your estimate of the "true probability" to see if the market agrees with you.


Bankroll Sizing: Tying Breakeven to Kelly Criterion

Once you establish that the true probability of your bet winning is greater than the breakeven percentage, the next question is “how much?”


Bet sizing with the Kelly Criterion gives you a way to do this. Here are the formulas you'll need to calculate the percentage of your bankroll to bet according to Kelly.


  • Kelly % = Edge / (Decimal Odds - 1)

  • Edge = (Probability * Decimal Odds) - 1

  • Positive American to Decimal: (Odds + 100) / 100

  • Negative American to Decimal: (|Odds| + 100) / |Odds|


We won't get into Kelly any more here, except to say that there are a few benefits to betting this way, and MANY potential pitfalls. See Chapter 5 of Secrets of Sports Betting for a detailed discussion. One of those potential pitfalls is Variance.


Variance: Why “Almost” Matters

Variance just means how much results bounce around compared to the average.

  • Low variance: Outcomes stay close to what you expect. (Example: flipping a coin 1,000 times → you’ll be near 50/50.)

  • High variance: Outcomes swing wildly before evening out. (Example: there might be stretches of 10 Heads in a row during your 1,000 flips.)


In betting, variance is why you can:

  • Make good bets and still lose in the short run.

  • Make bad bets and still win a few in the short run.


Variance doesn’t change your expected value. But it does reduce how fast your bankroll grows in the real world. Without getting too deep into the math, it's because your returns compound. Steady compounding is better than highs and lows.


This is why pros bet smaller fractions of their edge (½ Kelly, ¼ Kelly): it reduces variance and increases the probability of actually reaching the long-term growth rate.


How to Put This to Work Today

  1. Before you bet: Compute the breakeven % at the posted odds.

  2. Estimate true probability (using a model, handicapping, price discovery, market reading, etc.).

  3. If true probability > breakeven, it’s +EV. If not, pass.

  4. Size appropriately (low fractional Kelly or flat betting).

  5. Log every bet with the actual odds you played; review outcomes vs. expectation.


This is exactly how the pros do it: Price → EV → Size → Track.


Where This Fits in the Bigger Picture

In Secrets of Sports Betting, breakeven percentage is part of the “math that never goes out of style” toolkit—alongside no-vig pricing, synthetic lines, push rates, and practical bet sizing. These aren’t abstract formulas. They’re the foundation of every sharp decision you’ll make.


To make them usable day to day, Bettor Ed gives you the tools:

The book gives you the framework. The calculators do the math instantly. SlipSync closes the loop by showing you how your actual results line up with the theory.


TL;DR (Summary)

  • Breakeven % = the win rate you must hit at a given price to not lose money long term.

  • If your true win probability > breakeven %, the bet has positive expected value (+EV) and you'll win in the long run.

  • Know this for every bet before you place it. Everything else builds on this.


If you know your breakeven percentage every time you see a line, you’ll instantly separate yourself from 99% of bettors. It’s the simplest edge there is: don’t bet unless you’re above the hurdle.

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