You found +EV bets. You’re placing them consistently. And then you blow up your bankroll in two weeks because you were betting 10% of it on every play. Sound familiar?
Bankroll management is where +EV betting lives or dies. The math can be completely in your favor and you can still go broke if you size your bets wrong. Let’s fix that.
Why Bankroll Management Matters More for +EV
If you’re a recreational bettor throwing $50 on the Cowboys because you like them, bankroll management is about limiting losses. If you’re a +EV bettor, it’s about something different entirely: surviving variance long enough for the edge to play out.
Your edge on any single bet might be 3-5%. That’s real, but it’s small. Understanding expected value is a prerequisite — if you’re not placing +EV bets, no amount of bankroll management saves you. To turn that into consistent profit, you need to place hundreds of bets — and you need your bankroll to survive the inevitable cold streaks along the way.
The goal isn’t maximizing any single bet. It’s maximizing long-term growth while keeping the probability of going broke near zero.
The Basics: Units and Bankroll
Your bankroll is the total amount of money dedicated to betting. Not your savings account. Not rent money. Money you’ve set aside specifically for this.
A unit is a standard bet size, usually 1-2% of your bankroll. If your bankroll is $5,000, one unit is $50-$100.
| Bankroll | 1% Unit | 2% Unit |
|---|---|---|
| $1,000 | $10 | $20 |
| $2,500 | $25 | $50 |
| $5,000 | $50 | $100 |
| $10,000 | $100 | $200 |
Most serious +EV bettors bet between 1-3% of their bankroll per play. If that sounds small, good. It should.
Flat Betting vs. Kelly Criterion
Flat Betting (The Simple Approach)
Bet the same amount on every play regardless of your edge. One unit per bet, every bet.
Pros:
Dead simple
Hard to screw up
Removes emotion from sizing
Cons:
Doesn’t account for how strong your edge is
A 1% edge bet and a 10% edge bet get the same size
Flat betting at 1-2% of your bankroll is a perfectly fine approach. If you never move past this, you’ll still be in better shape than 95% of bettors.
Kelly Criterion (The Optimal Approach)
The Kelly Criterion calculates the mathematically optimal bet size based on your edge and the odds:
Kelly % = (Edge / Odds) or more precisely: (bp - q) / b
Where:
b = decimal odds - 1 (the profit per $1 wagered)
p = your estimated win probability
q = 1 - p (loss probability)
Example: A bet at +150 (2.50 decimal) where you estimate a 45% win probability:
b = 1.50
p = 0.45, q = 0.55
Kelly = (1.50 × 0.45 - 0.55) / 1.50 = (0.675 - 0.55) / 1.50 = 8.33%
Full Kelly says bet 8.33% of your bankroll. In practice, that’s too aggressive.
Try the kelly-criterion-calculator→
Why You Should Use Fractional Kelly
Full Kelly maximizes long-term growth in theory, but it assumes your probability estimates are perfect. They’re not. Nobody’s are.
Half Kelly (50%) is the most common approach among serious bettors. It gives up roughly 25% of the optimal growth rate but cuts your variance in half. The ride is dramatically smoother.
Quarter Kelly (25%) is even more conservative. Slower growth, but you’d need a catastrophic run of bad luck to put a real dent in your bankroll.
| Approach | Bet Size (from Kelly example) | Variance | Growth Rate |
|---|---|---|---|
| Full Kelly | 8.33% | Very High | Maximum |
| Half Kelly | 4.17% | Moderate | ~75% of max |
| Quarter Kelly | 2.08% | Low | ~50% of max |
| Flat 1% | 1.00% | Very Low | Steady |
We’d recommend starting with quarter Kelly or flat 1-2%. Move to half Kelly once you’ve tracked enough bets to trust your edge estimates.
The Biggest Bankroll Mistakes
Mistake 1: Betting Too Much Per Play
This is the killer. A 10% edge doesn’t mean you should bet 10% of your bankroll. Even with a real edge, a bad run of 5-6 losses in a row (which happens regularly) at 10% per bet can wipe out 40-50% of your bankroll. At that point, psychology kicks in — you start chasing, increasing bet sizes to recover, and the spiral starts.
The fix: Cap your max bet at 3-5% of your bankroll, period. Even if Kelly says bet more, don’t.
Mistake 2: Not Having a Dedicated Bankroll
If you’re betting from your checking account, you have no idea if you’re profitable. You can’t track performance, you can’t calculate proper unit sizes, and you’ll inevitably dip into money you can’t afford to lose.
The fix: Move a specific amount into a separate account (or at least track it separately). That’s your bankroll. Everything gets sized off that number.
Mistake 3: Not Adjusting as Your Bankroll Changes
If you start with $5,000 and run it up to $8,000, your unit size should increase. If you drop to $3,500, it should decrease. This is called a rolling bankroll and it naturally protects you — you bet less when you’re running bad and more when you’re running good.
The fix: Recalculate your unit size weekly or after every 50 bets.
Mistake 4: Ignoring Correlation
If you have 8 bets on the same NFL Sunday slate, those outcomes aren’t fully independent. A bad weather game or a weird injury cascade can sink multiple bets at once. Correlated losses hit harder than independent ones.
The fix: Be aware of how many bets you have in the same game, same slate, or same market. If you’re heavy on one event, consider reducing individual bet sizes.
A Simple System That Works
Here’s what works for most +EV bettors:
Set a bankroll — money you can afford to lose entirely
Start with 1% flat bets — boring, but bulletproof
Track everything — every bet, every result, your running ROI
After 200+ tracked bets, evaluate your actual edge and consider moving to half Kelly
Recalculate units weekly based on current bankroll
Never exceed 5% on a single bet regardless of how strong the edge looks
This won’t blow up your bankroll. It won’t make you rich overnight either. But it’ll compound over months and seasons, which is the whole point.
Key Takeaways
Bankroll management is about surviving variance long enough for your edge to compound
Start with 1-2% flat bets — it’s simple and effective
If using Kelly, use half or quarter Kelly — full Kelly is too volatile for imperfect probability estimates
Never bet more than 5% of your bankroll on a single play
Recalculate your unit size regularly as your bankroll changes
The bettors who go broke aren’t wrong about their picks — they’re wrong about their sizing
