In professional blackjack, your bankroll is not just money — it is your inventory. Without it, you are out of business. The difference between a gambler and an advantage player is that the advantage player treats bankroll with mathematical precision.
This calculator computes your Risk of Ruin (the probability of going broke), N0 (how many hands until skill reliably outweighs luck), and hourly expected value — the three numbers every card counter needs before sitting down at a table.
Blackjack Bankroll Calc
How to Use the Calculator
- Total Bankroll ($): The total amount of money you have dedicated exclusively to blackjack. This is not your life savings — it is your “business capital” that you can afford to lose.
- Bet Unit Size ($): Your minimum bet (table minimum or waiting bet). All calculations are based on this unit. A $25 unit with a 1-12 spread means your max bet is $300.
- Player Advantage (%): Your overall edge as a counter. Typical Hi-Lo ranges: 0.5-1.0% for standard games, 1.0-1.5% for excellent games with deep penetration. If unsure, start with 0.75% for a conservative estimate.
- Variance (per hand): This is σ² — the squared standard deviation per hand based on your bet spread. See the reference table below for typical values.
- Hands per Hour: Full table ≈ 60-80, heads-up ≈ 150-200. Speed directly multiplies your hourly EV.
Variance by Bet Spread
The variance input depends on how aggressively you spread your bets. A wider spread captures more edge but creates larger swings:
| Bet Spread | Variance (σ²) | Typical Edge | Style |
|---|---|---|---|
| Flat Betting (no spread) | 1.15 | 0% | Basic strategy only |
| 1-8 Spread | 1.2 | 0.5-0.8% | Conservative counter |
| 1-12 Spread | 1.3 | 0.8-1.2% | Standard professional |
| 1-16 Spread | 1.4 | 1.0-1.5% | Aggressive |
| 1-20+ Spread | 1.5+ | 1.2-2.0% | Team play / Wonging |
The 1-12 spread is highlighted because it is the most common configuration for solo counters on 6-deck shoes. If you are using this spread, enter 1.3 as your variance.
Understanding the Output
Risk of Ruin (RoR)
The probability of losing your entire bankroll before the positive expectation overcomes variance. The formula is: RoR = e^(−2 × Bankroll_in_units × EV / Variance). Green ( 5%) means your bankroll is too small — either reduce your unit size or increase your bankroll.
Professional benchmarks: 1% RoR ≈ Quarter Kelly (safest), 5% ≈ Half Kelly, 13.5% ≈ Full Kelly (maximum growth rate but high risk).
N0 (The “Long Run”)
N0 = Variance / EV². This is the number of hands where your cumulative expected profit equals one standard deviation. Before N0, your results are dominated by luck. After N0, your edge becomes statistically visible. A counter with 1% advantage and σ²=1.3 has N0 = 13,000 hands (about 130 hours at 100 hands/hour). A counter with 0.5% advantage has N0 = 52,000 hands (650 hours). Lower N0 is always better — it means you reach “the long run” faster.
Hourly EV ($)
Your expected profit per hour: Advantage% × Hands/Hour × Unit Size. At 1% edge, 100 hands/hour, $25 unit: $25/hour. This is an average — individual sessions swing wildly around this number. Use the Session Simulator to see realistic session-level outcomes, and the Variance Calculator for SD per hour and confidence intervals.
Real-World Examples
Example 1: The Well-Funded Counter
Inputs: $10,000 bankroll, $25 unit, 1.0% advantage, variance 1.3, 100 hands/hr.
Results: RoR = 0.2% (green — excellent), N0 = 130 hours, hourly EV = $25. This player has 400 units of bankroll — well above the 200-unit minimum for 1% RoR. They can expect to earn about $25/hour on average, reaching statistical significance after about 130 hours of play.
Example 2: The Underfunded Counter
Inputs: $5,000 bankroll, $25 unit, 0.5% advantage, variance 1.3, 80 hands/hr.
Results: RoR = 21.5% (red — dangerous), N0 = 650 hours, hourly EV = $10. With only 200 units and a slim 0.5% edge, this player has a 1-in-5 chance of going broke. Solutions: reduce unit to $15 (333 units → RoR drops to 4.5%), improve the edge by finding better penetration, or build the bankroll before playing.
Example 3: The Aggressive Professional
Inputs: $50,000 bankroll, $100 unit, 1.5% advantage, variance 1.4, 100 hands/hr.
Results: RoR
How Much Bankroll Do You Need?
If you want to work backwards from a target RoR, the formula is:
Required Bankroll (units) = −Variance × ln(RoR) / (2 × EV)
For a common scenario (1% edge, variance 1.3, target 1% RoR): Units = −1.3 × ln(0.01) / (2 × 0.01) = −1.3 × (−4.605) / 0.02 = 299 units. At $25/unit, that is $7,475. At $100/unit, it is $29,900.
Quick rule of thumb: for 1% RoR with a 1-12 spread, you need roughly 300 minimum bet units. For 0.5% RoR, you need about 350 units. For 5% RoR, about 200 units.
Related Blackjack Tools
- Variance Calculator — SD per hand/hour, N0, and confidence bands
- Session Simulator — Monte Carlo simulation of 1,000 sessions
- House Edge Calculator — Base house edge by table rules
- Penetration Calculator — How cut card depth affects your edge
- True Count Calculator — RC to TC conversion for bet sizing
- Deviations Calculator — Index plays that change with count
- Card Counting Guide — Complete Hi-Lo system walkthrough
- Basic Strategy Calculator — Optimal play for every hand