Craps Variance Calculator
Calculate session variance, standard deviation, and probability ranges for your craps play. Understand the impact of odds bets on volatility.
Formula:Session σ = √(Variance × Decisions) × Bet
Session Std Deviation
$173.21
17.3 units
Expected Result
$-4.44
0.37% edge
P(Profit)
49.0%
Different bets have different variance
$
Base bet (flat bet or line bet)
30-40 typical for line bets
How long you plan to play
Expected Result Ranges for 120 Decisions
Expected (Average)
$-4.44
68% Range (1σ)
$-178 to $169
95% Range (2σ)
$-351 to $342
Bet Type Variance Comparison
| Bet Type | Edge | Variance | $10 Session σ* |
|---|---|---|---|
| Pass Line | 1.41% | 1.00 | $110 |
| Don't Pass | 1.36% | 0.98 | $108 |
| Pass + 3-4-5x Odds | 0.37% | 2.50 | $173 |
| Don't Pass + Lay Odds | 0.27% | 2.80 | $183 |
| Place 6 & 8 | 1.52% | 0.87 | $102 |
| Place 5 & 9 | 4% | 1.08 | $114 |
| Field - Triple 12 | 2.78% | 1.39 | $129 |
*Session standard deviation for $10 bet over 120 decisions
Craps Session Simulator
Monte Carlo simulation with 1,000 iterations
$
Your initial capital
%
Your expected advantage
%
Percentage of bankroll per bet
Total bets to simulate
Key Facts
- •Pass/Don't Pass variance: ~1.0 per decision (flat bets only)
- •Pass + 3-4-5x odds variance: ~2.5 per decision
- •More odds = lower edge % but higher variance (bigger swings)
- •68% of sessions fall within 1 standard deviation of expected
- •Typical craps: 30-40 line bet decisions per hour
Frequently Asked Questions
What is variance in craps?
Variance measures how much your results can swing above or below expected. Craps has moderate variance for line bets (~1.0) but taking/laying odds increases variance significantly (2.5-3.0) because those additional bets are at true odds.
How do odds affect craps variance?
Taking or laying odds increases variance because you're betting more money at 0% house edge. While this reduces your overall percentage loss, the bigger bets create larger swings. A $10 Pass with 3x odds has similar variance to a $40 flat bet.
How many decisions per hour in craps?
A typical craps game sees about 30-40 decisions per hour for line bets, though this varies by table and shooter speed. Place bets can see 40-60 decisions since they resolve on any roll of their number or 7.
Why is craps variance important for bankroll?
Higher variance requires a larger bankroll to survive downswings. Even with Pass + odds (0.37% edge), you can easily lose or win 10+ betting units in a session due to variance. Understanding this prevents going broke during normal swings.
Try These Examples
Quick-start with common scenarios
How this works
Calculations follow the published mathematics of the game — combinatorics for cards, probability theory for dice, and expected-value accounting for wagers. Results are verified against independent references (primarily Wizard of Odds). No calculation here is an opinion or recommendation; it is arithmetic applied to the rules of the game.
What this tool can’t do
When to consult a professional
This tool computes probability and expected value. It is not a betting system and cannot predict the outcome of any individual wager. If gambling is causing problems for you or someone you know, call the National Problem Gambling Helpline at 1-800-GAMBLER.
Sources
- [1]Wizard of Odds — Michael Shackleford, ASAIndustrywizardofodds.comAccessed Apr 21, 2026
Actuary; widely cited casino-game probability reference. Used for house-edge and EV verification.
- [2]National Council on Problem GamblingOfficial sourcencpgambling.orgAccessed Apr 21, 2026
Responsible-gambling guidance and 1-800-GAMBLER helpline.
Joseph OrdunaFounder & Software Engineer
Full-stack software engineer specializing in embedded systems, web architecture, and AI/ML. Founder of Practical Web Tools. Built the gesture-controlled drone IP acquired by KD Interactive (Aura Drone, sold on Amazon).
Session Std Deviation
$173.21
17.3 units
Expected Result
$-4.44
0.37% edge
P(Profit)
49.0%