Bankroll & Position Size Calculator

How position sizing protects you

Your unit is simply your bankroll multiplied by the percentage you choose to risk — a $1,000 bankroll at 2% gives a $20 unit. The point of keeping it small is survival: losses compound, so capping each position means no single market can do serious damage, and you stay in the game long enough for skill to matter. The “flat losses to halve bankroll” figure shows how many losing trades in a row it would take to lose half your bankroll at a fixed dollar stake — a quick sense of how much cushion your chosen size gives you.

Choosing a percentage

A common, conservative range is 1–5% per position. Start at the lower end while you are learning and only size up once you have a measured, proven edge. The full reasoning — including flat versus percentage staking and the math of ruin — is in our guide to bankroll management. To size by the strength of each opportunity rather than a flat percentage, see the Kelly calculator.

Once you have a unit, check the payoff with the profit calculator and the trade’s edge with the EV calculator.

More calculators

Pair this tool with the others in the kit:

Frequently asked questions

How much should I risk per position?

A common, conservative range is 1-5% of your bankroll per position, and beginners are well served starting at 1-2%. The goal is that no single market can do serious damage, so you survive losing runs.

What is a betting unit?

A unit is your standard stake per position, usually set as a fixed percentage of your bankroll. Sizing in units rather than arbitrary dollar amounts keeps your risk consistent as your bankroll changes.

Why does small position sizing matter?

Because losses compound. Oversized positions can wipe out an account during a normal losing streak before a good edge has a chance to play out. Smaller units mean longer survival and let skill express itself over time.