Session Loss Calculator
Plan for the worst weekend you can still survive: this tool estimates the mean and spread of profit when you repeat the same style of bet several times in one session—so “bad luck” does not surprise you after the fact.
Enter your best estimate of win probability (from your model, not the public line), the decimal odds you actually get, flat stake size, and how many such bets you expect. The model assumes bets are independent and identically distributed—parlays, correlated markets, and moving lines violate that, so use the numbers as a baseline, not gospel.
Session P&L Mean & Volatility
σ on total P&L grows with √n for iid bets.
Adjust inputs to see expected session profit and a rough 95% range.
Table of Contents
How to Use This Calculator
Enter win probability, decimal odds, stake per bet, and bets in session. The tool reports expected session P&L, standard deviation, and a rough 95% band using independent identical bet assumptions.
iid model
Assumes each bet is independent with the same distribution—real trips may correlate.
Session length
How many bets you plan tonight, this weekend, etc.
Read σ and band
Variance scales with n; σ grows with √n.
Bankroll check
Compare σ to trip bankroll to see if you can survive normal swings.
Trip Risk
Short samples swing wildly even with edge. This calculator quantifies how wide session results might be under a simple model.
Examples
Example 1 — Defaults
p = 0.52, odds 1.91, stake 100, n = 25—check E[P&L], σ, and 95% band in the widget.
Example 2 — Shorter session
n = 5 shrinks σ but relative noise remains huge.
Example 3 — Underdog odds
Higher decimal widens per-bet variance—session σ jumps.
Frequently Asked Questions
It uses a normal-style multiple on σ—P&L is discrete, so treat as intuition.
Enter decimal odds in the odds field.
Correlation across live bets breaks iid—interpret cautiously.
Shows central tendency while σ captures dispersion—both matter.
If your p is below breakeven for the odds, mean session P&L turns negative.
