Bankroll Management Guide — Kelly Criterion & Staking
The difference between going broke and staying in the game is not your picks — it's your staking
Why Bankroll Management Matters
You can have a genuine +3% edge on every bet and still go broke. How? By overbetting. If you stake 20% of your bankroll per bet with a 50% win rate, a run of 5 consecutive losses (which happens 3.1% of the time) wipes out 67% of your bankroll. A run of 10 losses (0.1% probability — roughly once per 1,000 bet sequences) destroys 89%.
Bankroll management solves this by setting stake sizes that balance growth rate against ruin risk. The math is settled: the Kelly Criterion, published by John Kelly at Bell Labs in 1956, provides the mathematically optimal staking formula. Every professional bettor and quantitative fund uses some variant of it.
Flat Staking vs Proportional Staking
There are two fundamental approaches to sizing your bets:
Flat stakingmeans betting the same dollar amount on every wager. If your unit is $10, every bet is $10 regardless of your bankroll size or perceived edge. It's simple, eliminates emotional sizing decisions, and limits errors. The downside: it doesn't adapt — if your bankroll doubles, you're under-betting; if it halves, you're over-betting relative to bankroll.
Proportional staking means betting a fixed percentage of your current bankroll. If your rule is 2% and your bankroll is $1,000, you bet $20. If your bankroll grows to $1,500, your bet increases to $30. If it drops to $700, your bet decreases to $14. This automatically scales with your bankroll and makes it mathematically impossible to go to zero (since you're always betting a fraction of what remains).
| Feature | Flat Staking | Proportional Staking |
|---|---|---|
| Simplicity | Very simple | Requires recalculation |
| Adapts to bankroll | No | Yes, automatically |
| Can go to zero? | Yes (if enough losses) | Mathematically impossible |
| Growth rate | Linear | Exponential (compounds) |
| Best for | Beginners, recreational bettors | Serious bettors with accurate edge estimates |
Our recommendation:Start with flat staking at 1–2% of your initial bankroll. Switch to proportional staking once you've verified a positive edge over 500+ bets.
The Kelly Criterion Formula
Kelly Criterion calculates the optimal fraction of your bankroll to stake on a bet given your edge and the odds:
Kelly % = (b × p − q) / b
b= decimal odds − 1 (the profit multiplier)
p = your estimated probability of winning
q= 1 − p (probability of losing)
Worked Example
You estimate a team has a 55% chance of winning at decimal odds of 2.00:
b = 2.00 − 1 = 1.00
p = 0.55, q = 0.45
Kelly = (1.00 × 0.55 − 0.45) / 1.00 = 0.10 = 10%
Full Kelly says bet 10% of bankroll. On a $1,000 bankroll, that's $100.
But 10% per bet is aggressive. This is where fractional Kelly enters.
Full Kelly vs Fractional Kelly
Full Kelly maximizes the long-term growth rate of your bankroll. But it also produces stomach-churning drawdowns. In practice, professionals use a fraction of the Kelly stake:
| Kelly Fraction | Stake (from example) | Growth Rate | Max Drawdown | Best For |
|---|---|---|---|---|
| Full (1.0×) | $100 | Maximum | 50–80% | Theory only — no one should use this |
| Half (0.5×) | $50 | 87.5% of full | 30–50% | Aggressive professionals |
| Quarter (0.25×) | $25 | 75% of full | 15–25% | Most recommended — best risk/reward balance |
| Eighth (0.125×) | $12.50 | 56% of full | 8–15% | Very conservative, beginners |
Quarter Kelly is the sweet spot.You sacrifice only 25% of the maximum growth rate but reduce drawdowns by ~75%. On a $1,000 bankroll with a 10% full Kelly bet, quarter Kelly means $25 per bet — a comfortable 2.5% of bankroll.
Use our EV & Kelly calculator to compute Kelly stakes for any edge, odds, and bankroll size.
Dealing with Variance and Drawdowns
Even with a genuine edge, losing streaks are inevitable. Here's what to expect:
| Win Rate | Longest Expected Losing Streak (per 1,000 bets) | Drawdown at 2% Stakes |
|---|---|---|
| 55% | 11–13 losses in a row | −22% to −26% |
| 52% | 13–16 losses in a row | −26% to −32% |
| 50% | 15–18 losses in a row | −30% to −36% |
A 55% bettor placing 1,000 bets will almost certainly experience a 10+ bet losing streak at some point. At 2% flat stakes, that's a 20%+ drawdown. This is normal, not a sign that your strategy is broken.
Rules for surviving drawdowns:
1. Never increase stakes to recover faster.This is the martingale fallacy. If your edge is real, normal-sized bets will recover the drawdown over time. If your edge isn't real, bigger bets accelerate your ruin.
2. If using proportional staking, your stakes automatically decrease. This is a feature, not a bug. Smaller bets during drawdowns preserve capital for recovery.
3. Review your CLV, not your P&L.If your closing line value is still positive during the drawdown, your strategy is working — variance just hasn't caught up yet. If your CLV has turned negative, something has changed and you should pause.
4. Set a hard stop. If your bankroll drops below 50% of peak, reduce stakes to minimum and review your entire approach. This could be variance, but it could also mean your edge has disappeared (bookmaker adjusted lines, model became stale, etc.).
When to Increase or Decrease Unit Size
Increase units when:your bankroll has grown by 50%+ and you're using flat staking. Recalculate your unit to 1–2% of the new, higher bankroll. If using proportional staking, this happens automatically.
Decrease units when:your bankroll drops 25%+ from peak. Resize to 1–2% of your current (reduced) bankroll. This protects remaining capital.
Never change units because:you "feel confident" about a specific bet, you want to win back recent losses, or a tipster said a pick is a "lock". Emotional staking overrides are the number one bankroll killer.
Common Bankroll Management Mistakes
| Mistake | Consequence | Fix |
|---|---|---|
| Staking 10%+ per bet | 5 consecutive losses = 41%+ drawdown. 10 losses = 65%+. Ruin is likely. | Cap at 1–3% per bet. Use quarter Kelly maximum. |
| No bankroll separation | Betting from your checking account means no clear limit. Losses feel abstract until overdraft. | Dedicate a specific amount as bankroll. Track it separately from personal finances. |
| Using full Kelly | 50%+ drawdowns. One wrong probability estimate can wipe 20% of bankroll in a single bet. | Use quarter Kelly. Still captures 75% of growth with 75% less drawdown. |
| Tilting after losses | Emotional decisions → larger stakes, worse picks, faster ruin. | Pre-commit to staking rules. If you feel the urge to deviate, stop betting for 24 hours. |
| Ignoring margin in Kelly calc | Overestimates edge by 2–8%, leading to 2–8% too-large stakes on every bet. | Use fair (margin-removed) odds to estimate p, not raw bookmaker odds. |
FAQ
What percentage of my bankroll should I bet per wager?
Most professionals recommend 1-3% of your bankroll per bet. Conservative bettors use 1% (flat staking). If you use Kelly Criterion, quarter Kelly typically results in 1-4% stakes depending on your edge. Never exceed 5% of bankroll on a single bet — even with a large perceived edge, the risk of ruin becomes unacceptable.
What is the Kelly Criterion?
The Kelly Criterion is a mathematical formula that determines the optimal stake size to maximize long-term bankroll growth: Kelly % = (bp - q) / b, where b = decimal odds - 1, p = your estimated win probability, and q = 1 - p. It was developed by John Kelly at Bell Labs in 1956 and is widely used in both investing and professional sports betting.
Why use fractional Kelly instead of full Kelly?
Full Kelly maximizes long-term growth rate but produces extreme variance: 50%+ drawdowns are common. Quarter Kelly (dividing the Kelly stake by 4) achieves 75% of full Kelly’s growth rate while reducing maximum drawdown by roughly 75%. Most professional bettors use quarter to half Kelly for this reason.
How do I recover from a big drawdown?
Do NOT increase your stake size to ‘win it back’ — this is the fastest path to ruin. If using proportional staking, your stakes automatically decrease as your bankroll shrinks, which is the mathematically correct response. If using flat staking, resize your unit to 1-2% of your current (reduced) bankroll. Recovery takes time and more bets, not bigger bets.
Should I use the same stake for every bet?
Flat staking (same amount per bet) is simpler and limits mistakes. Variable staking (Kelly-based or confidence-weighted) can be more profitable if your probability estimates are accurate. If you’re a beginner, start with flat staking at 1-2% per bet. Graduate to fractional Kelly only after you’ve proven positive CLV over 500+ bets and trust your probability estimates.