Bankroll Management Calculator

Calculate how long your bankroll will last, find optimal bet sizes, and understand the math behind proper bankroll management.

Presets

Inputs

Starting Bankroll

Bet Size

House Edge 2.50%

Rounds per Hour hands, spins, or bets

Session Length hours

hrs

Results

Bet-to-Bankroll Ratio

ConservativeModerateAggressiveReckless

1.00% Moderate

Expected Loss per Hour

-$15.00

Expected Loss / Session-$60.00

Hours Until Expected Depletion (expected loss rate only, does not account for variance)66.7h

Total Bets / Session240

Units in Bankroll100.0

Responsible Bet Size (1%)+$10.00

After a 4-hour session with 240 bets, your bankroll change is expected to be between -$359.82 and +$239.82(95% confidence interval)

Estimated probability of depleting your bankroll this session: 0.0%

Bet Size Looks Good

Your bet is within safe bankroll management guidelines. The 1% rule recommends a maximum of +$10.00 per round.

Recovery Calculator

Current Bankroll

Target Bankroll

Sessions to TargetNot reachable on expectation

P(Reach Target Before Ruin)7.4%

With a house edge the expected path falls every session, so no number of sessions reaches the target on average. The probability above is the gambler's-ruin figure: the chance a flat bettor hits the target before hitting zero, for these stakes and this edge.

Session Tracker

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Start BR

End BR

Duration

hrs

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Why Bankroll Management Matters

The 1% Rule

The single most effective bankroll management strategy is deceptively simple: never risk more than 1% of your total bankroll on a single bet. This rule ensures that even a long losing streak, which is mathematically inevitable over time, cannot wipe you out. With 100 units in your bankroll, you can absorb 100 consecutive losses before going bust. That level of protection transforms gambling from a coin flip into a controlled, sustainable activity.

Bet Sizing Is Everything

Most players focus on picking the right game or strategy, but the single biggest factor in bankroll survival is how much you bet relative to what you have. A player with a $1,000 bankroll betting $10 per round will last dramatically longer than one betting $100, regardless of the game. The math is unforgiving: doubling your bet size does not just double your risk, it squares the rate at which variance can destroy your bankroll. This is why professional bettors obsess over position sizing above all else.

House Edge vs. Variance

The house edge is the long-term mathematical tax on every bet you place. It is small, predictable, and relentless. Variance, on the other hand, is the short-term chaos, the swings that make you feel like you are winning or losing far more than the edge would suggest. In a single session, variance dominates. Over thousands of bets, the house edge dominates. Understanding this distinction is critical: you can get lucky in the short run, but the house edge always wins in the long run. Bankroll management is about surviving variance long enough for the math to matter.

Why Small Edges Compound

A 2.5% house edge might sound trivial, but it compounds relentlessly. If you play 60 rounds per hour at $10 per bet, you are expected to lose $15 per hour. Over a 4-hour session, that is $60. Over a weekend trip with 20 hours of play, that is $300, nearly a third of a $1,000 bankroll. The insidious nature of the house edge is that it works slowly enough to be invisible on any single bet, but fast enough to be devastating over a session. This calculator helps you see the invisible tax before you sit down at the table.

Key Formulas

Expected Loss / Bet = Bet_Size × House_EdgeHours Until Ruin ≈ Bankroll / (Bet_Size × House_Edge × Rounds_Per_Hour)Session Std Dev = Bet_Size × √(Total_Bets)95% CI = Expected_Loss ± 1.96 × Session_Std_Dev

The Complete Guide to Bankroll Management

Bankroll management is the single most important skill separating recreational gamblers from professionals. It does not matter how sharp your handicapping is or how well you read a poker table, without disciplined bankroll management, variance will eventually destroy your balance. This guide explains the core concepts behind the calculator above and gives you a framework for protecting your capital.

Risk of Ruin: The Number That Matters Most

Risk of ruin (RoR) is the probability that your bankroll reaches zero before you hit a target profit. Even a bettor with a genuine 3% edge faces a meaningful risk of ruin if their bankroll is too small relative to their bet size. The math is unforgiving: a 100-unit bankroll with 2-unit bets and a 2% edge still carries roughly a 13% risk of ruin over an extended sample. Drop that bankroll to 50 units and the risk jumps above 36%. This calculator quantifies that risk so you can size your bankroll appropriately before risking a single dollar.

Gambler's Ruin: Why Negative-Edge Bettors Always Go Broke

The Gambler's Ruin theorem proves that a fixed-unit bettor with a negative expected value will go broke with mathematical certainty given enough time. It does not matter how large the bankroll is, the house edge grinds it to zero eventually. The only escape is either a genuine positive edge or a finite stopping rule. If you are betting into a negative-edge game (roulette, slots, most casino games), no bankroll management system can save you. It can only determine how long the process takes.

Why Bankroll Management Matters: Separating Variance from -EV

Variance is the natural fluctuation in results that every bettor experiences. Even a profitable bettor will have losing weeks, losing months, and occasionally brutal drawdowns. Bankroll management ensures you survive those drawdowns with enough capital to recover. Without it, you cannot distinguish between a bad run of variance and a genuinely losing strategy, because you will be broke before the sample size tells you anything meaningful.

Unit Sizing: The 1-5% Rule

Professional bettors express wagers as a percentage of their total bankroll, called "units." The standard recommendation is 1-5% per bet, with most professionals using 1-2% maximum. At 1% per bet, you need to lose 100 consecutive bets to go broke, an astronomically unlikely event for any serious bettor. At 5%, a bad losing streak of 20 bets can cut your bankroll in half. Flat betting at 1-2% is the simplest, most robust approach for the vast majority of bettors.

The Kelly Criterion Connection

The Kelly criterion calculates the mathematically optimal bet size to maximize long-term bankroll growth. It ties directly into bankroll management: Kelly tells you how much to bet, and your bankroll determines the dollar value of that percentage. Most professionals use fractional Kelly (quarter to half Kelly) to reduce variance at the cost of slightly slower growth. You can calculate your optimal Kelly stake with our staking plan calculator.

Bankroll Requirements by Game Type

Different gambling verticals have different variance profiles, which means different bankroll requirements. The table below gives general guidelines for a professional-level bankroll.

Game Type	Recommended Bankroll	Typical Unit Size	Variance Level
Sports Betting	50 - 100 units	1 - 3%	Medium
Poker (Cash Games)	20 - 30 buy-ins	3 - 5% per session	High
Poker (Tournaments)	100 - 200 buy-ins	0.5 - 1%	Very High
Blackjack (Card Counting)	200 - 500 units	0.5 - 1%	High
Roulette (Bias Play)	300 - 500 units	0.2 - 0.5%	Very High

These numbers assume a genuine positive edge. Without an edge, no bankroll is large enough. Use the drawdown calculator to model worst-case scenarios, and explore the staking plan calculator to compare flat, percentage, and Kelly staking strategies side by side.

Bankroll management reduces variance but does not eliminate it. A mathematically sound staking plan cannot turn a negative-edge game profitable. These projections assume your estimated win rate and odds are accurate. Even small errors compound over time. Never risk money you cannot afford to lose.

Understanding Bankroll Management

What Is Bankroll Management and Why It Matters

Bankroll management is the discipline of allocating your gambling funds in a way that maximizes the probability of staying in action long enough for your edge (if you have one) to manifest, while minimizing the risk of ruin from unavoidable short-term variance. Even a player with a genuine mathematical edge can go broke if they bet too large a fraction of their bankroll on any single wager: a string of normal losses at an oversized stake can wipe you out before the long-run edge kicks in.

Conversely, betting too small reduces your growth rate dramatically. The goal of bankroll management is to find the optimal staking level that balances growth with survival. This is not a matter of opinion. It is a mathematical optimization problem with a provably correct solution in idealized conditions.

Proper bankroll management applies equally to casino play, sports betting, poker, and any game with measurable probabilities. The specific formulas differ by context, but the core principle is universal: size your bets in proportion to your bankroll and your edge.

The Kelly Criterion

The Kelly Criterion, developed by John Kelly Jr. at Bell Labs in 1956, is the mathematically optimal staking formula for maximizing the long-run growth rate of a bankroll. It tells you exactly what fraction of your bankroll to wager given your edge and the odds on offer.

Full Kelly maximizes long-run growth rate but produces dramatic swings. Most professional bettors use fractional Kelly, typically half Kelly or quarter Kelly, which reduces variance significantly while sacrificing only modest growth rate. A half Kelly strategy, for instance, reduces drawdowns by roughly 75% while achieving approximately 75% of the maximum growth rate.

A critical caveat: Kelly is only optimal when your estimated edge is accurate. Overestimating your win probability leads to overbetting, which dramatically increases ruin risk. In practice, you should apply Kelly to a conservatively estimated edge, not a best-case estimate.

Fixed Percentage Staking

Fixed percentage staking (betting a fixed percentage of your current bankroll on every bet) is simpler than Kelly and has significant practical advantages. It naturally scales bets down when you are losing (protecting from ruin) and scales them up when you are winning (accelerating growth). It never results in zero. You can always bet a percentage of what remains.

Common fixed percentage recommendations: 1-2% for conservative bankroll management, 2-5% for moderate, and anything above 5% starts to carry meaningful ruin risk at typical win rates. At 2% per bet, you would need to lose 50 consecutive bets to lose approximately 63% of your bankroll, an extremely unlikely event for a player with any positive edge.

Fixed percentage staking does not account for varying edge across different bets. You bet the same percentage whether the edge is 1% or 5%. Kelly accounts for this by varying the stake proportionally to the edge. For bettors who cannot reliably estimate their edge per bet, fixed percentage is the safer default.

Risk of Ruin and Bankroll Sizing

Risk of ruin (RoR) is the probability of losing your entire bankroll before reaching a profit target. It depends on three variables: your win rate (edge), your bet size relative to bankroll, and your target.

This relationship shows why bet sizing matters exponentially. Doubling your bet size does not double your ruin risk. It raises it to a much higher power. A player betting 2% of bankroll with a 2% edge has roughly 14% ruin risk; the same player betting 1% has only 1.8% ruin risk. Halving bet size reduces ruin risk by 87%.

For casino games with a house edge, ruin probability approaches 100% given enough time at any bet size. The question becomes: how large must the bankroll be relative to session bet size to have a reasonable probability of reaching a stop-win target before being ruined?

Variance, Standard Deviation, and Common Mistakes

Variance is the mathematical measure of how spread out your outcomes are around the expected value. High-variance games (slots, parlays, certain poker situations) produce results far from the theoretical average over any short sample. Standard deviation quantifies this spread: approximately 68% of results will fall within one standard deviation of the mean over a session.

The most common bankroll management mistakes are: (1) betting too large relative to bankroll, confusing short-term good luck with edge; (2) chasing losses by increasing bet size after losses, the exact opposite of sound management; (3) not accounting for variance when setting win/loss stop limits; (4) using the same staking plan regardless of game type without considering the variance profile of different games; (5) overestimating edge, which leads to overbetting even when using a "correct" formula.

Reference Formulas

Kelly Fraction = (bp − q) / bRoR = ((1 − edge) / (1 + edge))^(Bankroll / Bet Size)σ = S × √(N × p × (1−p))

Frequently Asked Questions

How big should my bankroll be for sports betting?

A minimum of 50 units is recommended, where one unit is your standard bet size. This gives you enough cushion to weather normal variance without going broke. More serious bettors maintain 100-200 units. If you are betting $50/game, that means a $5,000-$10,000 dedicated bankroll before placing your first bet.

Should I use Kelly Criterion for casino games?

Generally no. Kelly is designed for +EV scenarios. Casino games have a house edge, meaning Kelly would recommend betting 0 (or negative, which is impossible). For casino play, use fixed session bankrolls with strict stop-loss limits rather than Kelly-based staking. The goal becomes managing entertainment time and variance, not maximizing growth.

What is the difference between Kelly and fractional Kelly?

Full Kelly maximizes long-run growth rate but produces extreme variance. Drawdowns of 50%+ are common even with a real edge. Fractional Kelly (e.g. half Kelly = bet 50% of the Kelly-recommended amount) dramatically reduces variance while giving up some growth rate. Most professional sports bettors use quarter Kelly to half Kelly in practice.

How do I know if I have enough of a sample to evaluate my bankroll management?

Statistical significance in betting requires hundreds to thousands of bets. At 55% win rate with even-money bets, you need approximately 1,000 bets to be 95% confident the edge is real (not luck). Before that, your results are consistent with both having an edge and being on a lucky streak. Track every bet meticulously and avoid drawing conclusions from fewer than 500 results.

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