Bankroll Calculator(2026)

A bankroll calculator turns your bankroll, edge, and variance into a recommended bet size and a live ruin probability. This page covers four contexts — sports betting, blackjack, poker and video poker — in one tool, with Monte Carlo simulation so you can see realistic best and worst paths instead of just averages.

Pick a sizing method (flat, Kelly, fractional, units, or custom percentage), enter your edge and variance, and the calculator returns a per-bet unit. The default for most bettors is 1% flat or half-Kelly — both keep ruin probability low without leaving meaningful growth on the table.

For sports betting, half-Kelly or 1–2% flat staking are the two evidence-supported defaults. Full Kelly assumes you know your edge precisely; almost no one does. Half-Kelly cuts long-run growth by about 25% but cuts variance roughly in half, which is a trade most bettors should make.

Use Kelly when your edge is confidently measured (1,000+ logged bets, closing-line value tracked). Use flat when edge is estimated, fuzzy, or new. Fractional Kelly (0.25–0.5) is the practical middle ground — most professional bettors live there.

For sports betting, 50–100 units is the rough minimum (so a $10 unit means $500–$1,000 bankroll). For card-counting blackjack, 200+ units. For cash-game poker, 25–40 buy-ins of your typical stake. For tournaments, 100–200 buy-ins. The calculator backs this out from your unit and ruin tolerance.

The 1% rule says size each bet at 1% of your current bankroll. It's popular because it survives almost any realistic downswing, recovers compound growth on wins, and never requires precise edge estimation. It's a strong default for anyone who hasn't logged 1,000+ bets.

Risk of ruin is the probability that your bankroll falls to zero (or a stop-loss threshold) over a given horizon. It matters because two plans with the same average profit can have wildly different ruin probabilities — and the one with high ruin will eventually bust you, even if it looks great on paper.

Yes — switch the mode tab at the top. Blackjack uses house edge in percent and bets-per-hour; poker uses bb/100 and hands-played; video poker uses optimal-play house edge and max-coin sizing. The variance presets and ruin formulas adapt automatically.

Fractional Kelly multiplies the full Kelly bet size by a fraction (commonly 0.25, 0.5, or 0.75). Half-Kelly cuts variance roughly in half while keeping about 75% of long-run growth — a near-optimal trade. Quarter-Kelly is for bettors who feel any drawdown sharply.

Set edge to 0 and use 1% flat staking. The calculator still gives a meaningful ruin probability and a sustainable unit size. As you log results, refine the edge estimate up or down. Never assume positive edge until 1,000+ bets prove it.

Higher variance widens the distribution of outcomes — more big wins, more big losses, deeper drawdowns. Two strategies with identical expected value but different variance have very different ruin probabilities. The calculator's variance preset (low/medium/high) is calibrated to typical game-specific values.

Only if your bankroll genuinely grew — the percentage method scales naturally. Avoid increasing the percent itself after a streak; that's winner's tilt. The math of your edge does not change because of recent results, and most streaks are within normal variance.

Bankroll is total money set aside for betting. A unit is a standard per-bet size, usually 1% of bankroll. Tracking results in units instead of dollars normalizes performance across bankroll sizes and makes ROI comparisons honest.

This page is the universal hub — it answers 'what unit should I bet right now and how risky is it?' across four game types. The Bankroll Growth Calculator is a specialist projector that compounds expected growth over thousands of sessions and visualizes ROI curves. Use this hub for sizing decisions, the growth calculator for long-term planning.