Finance

Sports Betting Bankroll Calculator

Built by Kevin Glover · @gloverbuilds · Verified formula

Calculate optimal unit size, monthly budget, and risk of ruin based on your bankroll, win rate, and betting volume.

📅 Updated April 2026 ✅ Formula verified 📖 4 min read 🆓 Free · No sign-up

In this article

The Foundation of Profitable Betting
Unit Sizing Strategies

The Foundation of Profitable Betting

Bankroll management is more important than picking winners. A 55% bettor with poor bankroll management will go broke. A 52% bettor with disciplined unit sizing will grind profit over time. The core rules: never bet more than 1-5% of your bankroll on a single bet, never chase losses by increasing bet size, and track every bet meticulously.

Unit Sizing Strategies

Flat betting (1-3% units): Same amount on every bet. Simplest and safest. Recommended for beginners. Kelly Criterion: Variable sizing based on edge — larger bets when you have a bigger edge. Mathematically optimal but requires accurate probability estimates. Confidence-based: 1 unit on standard plays, 2 units on high-confidence plays, 3 units on max confidence. Popular but risky if confidence does not correlate with actual edge.

⚡ CalcWolf Insight

The single most common mistake recreational bettors make: chasing losses by doubling bet size. This is a martingale strategy and it has a 100% probability of catastrophic failure given enough time. After a loss, bet the same amount or less — never more. Your edge comes from selection, not from sizing.

Frequently asked questions

How much should I start with for sports betting?▾

Start with an amount you can afford to lose entirely — most beginners lose their initial bankroll while learning. $500-2,000 is a reasonable starting bankroll. At 1-2% unit sizing, this means $5-40 per bet. Never fund your bankroll with money needed for bills, savings, or debt payments.

What is risk of ruin?▾

Risk of ruin is the probability of losing your entire bankroll even if you have a positive edge. It depends on edge size, unit size, and bankroll depth. A 53% bettor at -110 with 100-unit bankroll (1% units) has less than 1% risk of ruin. The same bettor with 20-unit bankroll (5% units) has roughly 30% risk of ruin.

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Kevin Glover · @gloverbuilds

Founder, CalcWolf · GLVTS · Blickr

All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →