Good position sizing is what keeps a losing streak from taking you out. This calculator helps you size a Kalshi trade two ways: a simple fixed percentage of your bankroll, and the Kelly criterion based on your edge.
Enter your bankroll and trade details below. This is educational, not financial advice.
FIXED PERCENTAGE
STAKE
$20.00
2% of bankroll
KELLY CRITERION (edge-based)
Kelly fraction (conservatism)
FULL KELLY
10.0%
of bankroll (aggressive)
SUGGESTED STAKE
$50.00
0.5x Kelly
≈ CONTRACTS
100
at 50¢
Full Kelly maximizes long-run growth but is very volatile, so most traders use a fraction (half or quarter). This is educational, not financial advice. Only risk what you can afford to lose.
Fixed percentage
The simplest discipline is risking a small, fixed slice of your bankroll per trade. It is easy to follow and keeps any single loss from doing real damage. Many traders use something in the low single digits of percent.
The Kelly criterion
Kelly sizes your stake based on your edge: the bigger your advantage, the more it suggests betting. Full Kelly is mathematically optimal for long-run growth but very volatile, so most traders use a fraction (half or quarter Kelly). This tool shows full Kelly and a more conservative fractional stake.
FAQ
How much should I bet on a Kalshi trade?
A common approach is a small fixed percentage of your bankroll, or a fraction of the Kelly stake based on your edge. This calculator gives both. Conservative sizing is the consistent theme.
What is the Kelly criterion?
A formula that sizes your bet according to your edge and the odds. Full Kelly maximizes long-run growth but is volatile, so most traders use half or quarter Kelly.
Why does position sizing matter?
Because even a real edge comes with losing streaks. Sizing small lets you survive the downswings and keep trading your edge instead of going broke on variance.
Stop calculating one trade at a time
ContractTax does this across your whole Kalshi history: real P&L, a Sharp Score that rates your edge, and your tax numbers under every treatment.
These tools are for education and estimation only, not financial or tax advice. Fee estimates use Kalshi’s standard formula and may differ from your actual fees.