Tool · Trading / Risk management
Calculate a position size from account equity, risk tolerance, entry price, and stop price. Add a target and win rate to calculate reward-to-risk and expectancy in R.
What it calculates
Trade direction
A stop below the entry price is treated as a long trade. A stop above entry is treated as a short trade. Entry and stop cannot be equal.
If a target is supplied, it must be on the profitable side of the entry: above entry for a long trade, or below entry for a short trade. A win rate can only be supplied when a target is also present because expectancy depends on the resulting R multiple.
Developer / agent interface
POST https://www.ytonlabs.com/api/position-sizing
curl -X POST \
https://www.ytonlabs.com/api/position-sizing \
-H "Content-Type: application/json" \
-d '{
"accountSize": 10000,
"riskPct": 0.01,
"entryPrice": 100,
"stopPrice": 95,
"targetPrice": 115,
"winRate": 0.40
}'
{
"positionSize": "20.00000000",
"riskAmount": "100.00",
"rMultiple": "3.0000",
"expectancy": "0.6000"
}
Scope
The returned position size is a mathematical result from the supplied inputs. Real orders can be constrained by factors that this version deliberately does not model.