Bankroll and units

What counts as a bankroll

A bankroll is the money set aside for trading, and nothing else. The National Council on Problem Gambling puts the rule plainly: never gamble with funds meant for necessities like rent, bills or savings NCPG. Its toolkit adds two habits that fit trading too: budget it like entertainment, and always expect to lose it NCPG toolkit.

Keep it in one place. If you trade on Kalshi, the simplest version is to deposit your bankroll once and set a personal funding cap so a bad night can't pull in more Kalshi RT Hub. When the bankroll is gone, the month is done. You don't refill it from rent money. Lesson 04 covers how to hold that line.

Units: one slice, every time

A unit is a fixed slice of the bankroll. House convention We use 1 unit = 1 to 2% of bankroll. That range is our own rule, not an industry standard, and we say so every time we use it. It's small on purpose: it keeps a normal losing run survivable and makes every result on our record comparable.

Here is what ten losses in a row do at different sizes, when each trade is a fixed share of whatever is left. This is arithmetic, not a forecast:

The 5% ceiling

No single position gets more than 5% of the bankroll, however good it looks. betstamp's guide says it directly: no sports bettor should risk more than 5% of their bankroll on any one bet betstamp. Two positions on the same game or the same fight count as one position for this rule.

Kelly, only as 1/4 Kelly

The Kelly criterion sizes a bet from your edge. For a Kalshi contract that pays $1, it works out to:

Full Kelly share = (your probability − price) ÷ (1 − price)

The catch is that your probability is an estimate. If it's too high, full Kelly overbets, and it can suggest wild sizes. betstamp's own example, a 60% chance at even money, gives 20% of the bankroll at full Kelly, which it calls far too aggressive betstamp. So we only teach 1/4 Kelly, and the 5% cap still applies on top. If the formula says zero or less, the right size is no trade.