Flat Betting Calculator
The honest baseline. Calculate expected value for constant bet sizing and understand why all systems have identical EV.
The Honest Baseline
Flat betting is not a "system"—it's the truth. Every betting system claims to give you an edge through clever bet sizing. But mathematics proves they all have identical expected value.
- Expected value is determined by the game, not your bets: The probabilities and payouts define EV. Bet sizing can't change the house edge percentage.
- All systems lose at the same rate: Per dollar wagered, Martingale, Fibonacci, Labouchere, and flat betting all lose the same percentage. The house edge is inescapable.
- Systems only change the experience: Progression systems alter variance (swings) and ruin timing (when you go broke), but not the expected outcome. Some systems feel safer, but all reach the same mathematical destination.
- Flat betting reveals the truth: Because flat betting is simple and unchanging, it makes the house edge obvious. Systems obscure this truth with complexity and short-term variance.
Use this calculator to find the expected value of any game. Then realize: every betting system playing that game has this exact same EV. The only way to win is to find positive EV opportunities—not to dress up negative EV in clever bet sizing.
Quick Examples
Betting Parameters
Your starting funds
Fixed amount per bet
Maximum bet allowed
e.g., 48.65% for roulette
e.g., 1 for even money
For analytics projection
How It Works
How Flat Betting Works
Flat betting is the simplest betting strategy imaginable: bet the same amount every time. Win or lose, you always bet your base unit. No progressions, no adjustments, no systems. Just consistent, unchanging bet sizing.
Why Flat Betting Matters
Flat betting is not exciting. It won't help you "recover losses" or "lock in wins." But it serves a critical educational purpose: it reveals the truth that all betting systems try to hide.
All betting systems have the exact same expected value as flat betting.
This is a mathematical certainty, not an opinion. Whether you use:
- Martingale (doubling after losses)
- Fibonacci (sequence-based progression)
- Labouchere (cancellation system)
- Oscar's Grind (conservative positive progression)
- D'Alembert (adding/subtracting units)
- Kelly Criterion (proportional betting)
- Flat betting (constant sizing)
...they all have the same expected value per bet when playing the same game.
Expected Value Formula
For a single bet:
Where:
- p = probability of winning
- q = probability of losing (1 - p)
- winAmount = bet size × payout multiplier
- lossAmount = bet size
Example: Roulette Red
Single-zero roulette, betting $10 on red (even money, 1:1):
- Win probability: 18/37 = 48.65%
- Loss probability: 19/37 = 51.35%
- Win amount: $10 × 1 = $10
- Loss amount: $10
Over 1,000 bets of $10 each, your expected loss is $270. This is true whether you use flat betting or any progression system.
What Betting Systems Actually Change
If betting systems can't change expected value, what do they change?
| System | Expected Value | Variance | Ruin Risk |
|---|---|---|---|
| Flat Betting | -2.7% | Low | Gradual |
| Martingale | -2.7% | Extreme | Sudden |
| Fibonacci | -2.7% | High | Moderate |
| Oscar's Grind | -2.7% | Low-Medium | Gradual |
Systems change the path to the same destination. Martingale gets you there with wild swings and sudden bankruptcy. Flat betting gets you there steadily. Oscar's Grind gets you there slowly. But all arrive at the same expected loss.
Use This Calculator
Enter your game parameters below to calculate the expected value for flat betting. Then compare this EV to any betting system—you'll find they're identical. This calculator reveals the honest mathematical truth behind all betting strategies.
Frequently Asked Questions
Learn More: Guides
Why Betting Systems Always Fail
Mathematical proof of why the Martingale, Fibonacci, Labouchere, and Oscar's Grind cannot overcome the house edge.
Kelly Criterion & Flat Betting Guide
The only approaches with a mathematical foundation — flat betting as the honest baseline and Kelly for genuine positive EV.
Related Calculators
Expected Value Calculator
Calculate EV for any bet type with detailed probability breakdowns.
Martingale Simulator
See how aggressive doubling produces the same EV as flat betting, just higher variance.
Oscar's Grind Simulator
Compare conservative progression to flat betting and confirm identical EV.
Kelly Criterion Calculator
For positive EV games only, Kelly optimizes bet sizing for growth.
Educational Disclaimer
This calculator is provided for educational purposes only. It demonstrates mathematical principles and does not constitute betting advice or encouragement to gamble. All casino games have negative expected value—the house always wins in the long run. See our full disclaimer.