Defining a bankroll, and why nothing works without one

A bankroll is a sum set aside for betting and separated from money that has a job. Everything downstream — unit size, return, drawdown, risk of ruin — is defined relative to it and undefined without it.

It is the denominator. A record with no fixed denominator cannot be read afterwards, because the same selections staked differently produce completely different results and there is no way to separate the two effects.

The size matters far less than the fixedness. A small bankroll applied consistently produces a readable record; a large one applied by mood does not.

And that is the trap. Not having one feels like flexibility rather than like an omission, and the cost only becomes visible months later when the record turns out to mean nothing.

What to do with it. Set aside an amount you can lose entirely without consequence, keep it in a separate account, and define a unit as a fixed percentage of it.