Learn / Risk of Ruin
Will the bankroll survive the variance? Risk of ruin for sports betting.
The math behind why a 2 percent edge bettor still goes broke at the wrong unit size. NuroPicks targets RoR under 1 percent on every published stake.
Plain-English answer
Risk of ruin is the probability that a sports betting bankroll hits zero before your statistical edge has time to play out. The standard approximation is RoR equals ((1 minus edge) divided by (1 plus edge)) raised to the power of (bankroll divided by average bet). A 2 percent edge bettor sizing 5 percent units carries a roughly 67 percent chance of going broke. Drop unit size to 1 percent and risk of ruin collapses to about 1.8 percent. NuroPicks publishes quarter Kelly stake recommendations on every Pro and Elite pick, which keeps RoR under 1 percent for a 55 to 60 percent win-rate model. Run any bankroll plus stake combination through /kelly in the Discord server to see the recommended unit size and the implied risk of ruin.
The formula
RoR = ((1 - edge) / (1 + edge)) ^ (bankroll / unit)
- edge is the per-bet expected value as a decimal (a 2 percent edge is 0.02).
- bankroll is the total roll dedicated to betting.
- unit is the average bet size in dollars.
- The exponent bankroll / unit is the number of units in the roll. More units equals lower RoR.
This approximation assumes flat staking and a binary win or loss bet at roughly even money. Real betting with mixed odds and varying stakes runs slightly higher RoR than the formula suggests, which is why fractional Kelly exists.
Worked example
Sharp bettor with a verified 2 percent edge against the closing line. Bankroll is 1,000 dollars. Compare three unit sizes side by side.
- 5 percent unit (50 dollars, 20 units in roll): RoR ~= 67 percent
- 2 percent unit (20 dollars, 50 units in roll): RoR ~= 13.5 percent
- 1 percent unit (10 dollars, 100 units in roll): RoR ~= 1.8 percent
Same edge, same bettor, same year. The only difference is the unit size, and the 5 percent bettor is twice as likely to bust as to ever realize the long-run edge. This is why disciplined bettors quote bankroll in units, not dollars.
Run a bankroll, edge, and odds combination through /kelly in the Discord server and the bot will return the quarter, half, and full Kelly stakes against your tracked bankroll, which is the cleanest way to keep RoR under 1 percent.
The four rules NuroPicks plays by
- Target RoR under 1 percent. Anything above 5 percent is a slow-motion bankroll wipe. Above 20 percent the year ends in zeros for a third of bettors with the same edge.
- Hold 100 units minimum in the roll. A 1,000 dollar bankroll sizes 10 dollar units. A 5,000 dollar bankroll sizes 50 dollar units. Anything tighter and a normal 8 to 12 bet losing streak ends the season.
- Cap any single stake at 5 percent of bankroll. Even on max-edge picks, the published quarter Kelly stake never exceeds 5 percent. Variance does not respect conviction.
- Re-size the unit monthly, not per pick. Bankroll growth or drawdown above 25 percent triggers a unit recalculation. Resizing per pick produces martingale-style chases and breaks the RoR math.
Pair with the rest of the bankroll stack
Risk of ruin is the survival floor. Use it alongside Kelly Criterion for stake sizing, bankroll management for monthly review, and units vs dollars for tracking.
21+ only. Not financial advice. 1-800-GAMBLER.
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