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Blackjack Calculator: House Edge, EV & Bankroll Tools

Three free calculators to plan your sessions, understand your odds, and size your bankroll. Plug in your numbers and see exactly what the math says.

Tool 1: House Edge Calculator

Select your table rules and see the exact house edge. Use this before sitting down at any table — it takes 10 seconds and tells you whether the game is worth playing.

House Edge Calculator

Select your table rules to calculate the house edge and RTP.
House Edge
Return to Player (RTP)
Expected Loss / $1,000 wagered
Game Quality

Tool 2: Session EV & Variance Calculator

Plan your session: enter your bet size, hours, and the house edge from Tool 1. See your expected loss, standard deviation, and the realistic range of outcomes (95% confidence interval).

Session EV & Variance Calculator

Calculate expected results and swing range for your session.
Total Hands
Total Action (wagered)
Expected Loss (EV)
Session SD
95% Range (2 SD)
Chance of Winning Session

Tool 3: Bankroll & Risk of Ruin Calculator

Are you properly funded? Enter your bankroll and playing conditions to see your risk of going broke.

Bankroll & Risk of Ruin

Calculate your risk of ruin, N0, and expected hourly results.
Bankroll in Units
Risk of Ruin
Expected Loss Per Hour
N0 (skill visible after)
Assessment

How the Formulas Work

Transparency matters — here are the exact formulas each calculator uses, so you can verify the math yourself.

House Edge Calculator: Starts from a baseline edge for each deck count (1 deck: 0.17%, 2: 0.31%, 4: 0.42%, 6: 0.46%, 8: 0.48%), then adds or subtracts rule adjustments: H17 (+0.22%), 6:5 payout (+1.39%), no DAS (+0.14%), no surrender (+0.07%), no re-split Aces (+0.08%). These values come from the Wizard of Odds house edge calculator.

Session EV & Variance: EV = Bet × Hands × (−Edge/100). SD = Bet × SD_per_hand × √Hands. The 95% range = EV ± 2×SD. Winning probability uses a normal distribution approximation: P(win) = 1 − Φ(0, EV, SD), where Φ is the cumulative distribution function.

Risk of Ruin: For negative-edge players: RoR ≈ e^(−2 × edge × bankroll_units / variance). For positive-edge players (counters): same formula but edge is positive, giving RoR < 100%. N0 = Variance / Edge². All formulas from Blackjack Apprenticeship and GamblingCalc.

How I Use These Tools

Before every trip to the casino, I plug my planned bet level and session length into the Session Calculator. It sets my expectations: "Tonight, I'll probably lose about $15, but I could be anywhere from −$400 to +$370." Knowing that range in advance prevents me from panicking during a downswing or getting overconfident during an upswing. It's emotional armor built from math.

For Card Counters
Enter a negative house edge value (e.g., −1.0 for a 1% player advantage) in the Risk of Ruin calculator. Set variance to 1.32 for flat betting or higher (8–20) for spread betting. The calculator will show your RoR and N0 for your specific conditions.

FAQ — Blackjack Calculator

How do I calculate blackjack house edge?
Select your table rules in Tool 1 above. The calculator starts from a baseline edge per deck count and adjusts for each rule (S17/H17, payout ratio, DAS, surrender, re-split Aces). For detailed rule impacts, see house edge explained.
What is expected value (EV) in blackjack?
Your average win or loss per session. Formula: EV = Bet × Hands × (−House Edge). For $10 bet, 300 hands, 0.5% edge: EV = −$15. See odds and probabilities for more context.
What standard deviation should I use?
For basic strategy flat betting: 1.14 units per hand (variance 1.32). For card counters with 1-12 spread: ~3.5–4.5 units. For more, see variance and standard deviation.
How do I calculate risk of ruin?
RoR ≈ e^(−2 × edge × bankroll_units / variance). Use Tool 3 above — enter your bankroll, bet size, edge, and variance. For recreational players, target RoR below 10%. See bankroll management.

Sources & References

  1. Wizard of Odds — "Blackjack House Edge Calculator": Industry-standard rule-by-rule house edge calculator. wizardofodds.com
  2. GamblingCalc — "Blackjack EV Calculator: Expected Value, Edge & Variance": SD per hand (1.142), session variance formulas. gamblingcalc.com
  3. GamblingCalc — "Blackjack Bankroll Calculator: Risk of Ruin & N0 Tool": RoR formula, N0, and Kelly criterion. gamblingcalc.com
  4. Blackjack Apprenticeship — "Blackjack Math: The Mathematics Behind Advantage Play": N0, CE, and risk-adjusted return formulas. blackjackapprenticeship.com
  5. Wizard of Vegas — "EV and Standard Deviation in BJ": Community-verified SD calculation (1.15 × AvgBet). wizardofvegas.com