Interactive tool

Roulette Losing Streak Calculator

See how likely brutal runs really are – and what they do to systems.

Long losing streaks are where most roulette systems break. This calculator estimates the probability of hitting a streak of X consecutive losing spins within a session, and shows how that streak would stress classic Martingale and Fibonacci progressions.

Choose your wheel, bet type, losing-streak length and number of spins. Optionally add your base stake to see how big the bets and bankroll requirements become under aggressive systems.

📉 Odds of X losses in a row 🎡 European & American wheels 🧪 Martingale & Fibonacci stress test

Estimate losing streak odds

Wheel type

Bet type

System analysis below assumes even-money bets, but streak odds work for all bet types.

Losing streak length (consecutive losses)

Number of spins in session

Base stake per spin (optional)

Used to estimate bet sizes and bankroll requirements for progressions.

Results

Core streak probabilities

Lose probability (single spin)

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Probability of exactly L losses starting at a specific spin

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Approx. chance of at least one L-loss streak in the session

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Session context

Wheel & bet

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Session length

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Streak length L

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System stress test (even-money systems)

The numbers below assume you’re using the progression on an even-money bet (red/black, odd/even, high/low). For other bet types, streak odds are correct but system exposure will differ.

Martingale (classic double after loss)

Max bet in a L-loss streak

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Total exposure needed to survive L losses

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Units (for reference)

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Fibonacci (sequence-based)

Max bet in a L-loss streak

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Total exposure over L losses

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Units (for reference)

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These are simplified, “worst-case” numbers – assuming you never hit a win during the streak. Real play will mix wins and losses, but planning for the worst case helps you understand how dangerous long streaks are for progression systems.

How the losing streak math works

The calculator uses a simple independent-trials model, which is more than accurate enough to understand risk levels for normal session lengths.

Key ideas

Single-spin lose probability

q = 1 − win_prob. For an even-money bet on a European wheel, that’s 19/37 ≈ 51.35%.
Exact L-loss streak at a starting point

P(L losses in a row) = q^L. For example, 8 losses in a row with q ≈ 0.5135 is 0.5135^8.
At least one L-loss streak in a session

Approximation: 1 − (1 − q^L)^(N − L + 1), where N is the number of spins. This looks at all possible starting positions for a streak of length L.
Martingale exposure

To survive L consecutive losses with base unit 1, you need 2^L − 1 units of bankroll; the maximum single bet is 2^(L−1) units.
Fibonacci exposure

For L consecutive losses, the bet level reaches the L-th Fibonacci number. Total exposure is roughly the sum of the first L Fibonacci numbers.

Why this matters for roulette systems

It’s easy to underestimate how common long losing streaks are, especially on even-money bets that “feel” close to 50/50. Systems like Martingale, Fibonacci and Labouchere all become dangerous when you hit those streaks – that’s where table limits and finite bankrolls collide with nice-looking theory.

Use this calculator together with the systems library and the responsible gambling guide to decide whether a strategy is compatible with your real-world risk tolerance, not just your curiosity.