{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"position-sizing"},"result":{"entity_type":"calculator","id":"position-sizing","calculator_id":"position-sizing","canonical_url":"https://tttkmbb.com/investing/position-sizing","name":"Position Size Calculator","title":"Position Size Calculator – Shares to Trade from Account Risk Percent and Stop-Loss Distance","category":"investing","category_name":"Investing & Real Estate","tool_name":"calculate_position_size","featured_mcp_tool":false,"description":"Computes how many shares (or units) to buy or short so that hitting the stop-loss loses a fixed percentage of the account, using the fixed-fractional method: risk amount divided by the risk per share.","use_when":"You have an entry and stop-loss price and want the number of shares that keeps the potential loss at a chosen fraction of the account.","do_not_use_when":"You want the mathematically optimal fraction to bet from a known edge (Kelly criterion) or the reward side of the trade (use risk-reward-ratio). Informational only; not financial advice.","inputs":[{"name":"account_size","label":"Account size","type":"number","required":true,"max":1000000000000,"exclusive_min":0,"description":"Total trading capital.","example":50000},{"name":"risk_percent","label":"Risk per trade","type":"number","unit":"%","required":true,"max":100,"exclusive_min":0,"description":"Share of the account you are willing to lose if the stop is hit (commonly 0.5–2 %).","example":1},{"name":"entry_price","label":"Entry price","type":"number","required":true,"max":1000000000,"exclusive_min":0,"description":"Planned entry price per share or unit.","example":100},{"name":"stop_loss_price","label":"Stop-loss price","type":"number","required":true,"min":0,"max":1000000000,"description":"Price at which the trade is exited at a loss; below the entry for a long, above it for a short.","example":95}],"outputs":[{"name":"risk_amount","label":"Risk amount","type":"number","decimals":2,"description":"account_size × risk_percent / 100."},{"name":"risk_per_share","label":"Risk per share","type":"number","decimals":4,"description":"|entry_price − stop_loss_price|."},{"name":"stop_distance_percent","label":"Stop distance","type":"number","unit":"%","decimals":2,"description":"risk_per_share / entry_price × 100."},{"name":"shares","label":"Shares to trade","type":"integer","decimals":0,"description":"floor(risk_amount / risk_per_share)."},{"name":"position_value","label":"Position value","type":"number","decimals":2,"description":"shares × entry_price."},{"name":"position_percent_of_account","label":"Position as % of account","type":"number","unit":"%","decimals":2,"description":"position_value / account_size × 100 (above 100 % requires leverage)."},{"name":"actual_risk_amount","label":"Actual risk with whole shares","type":"number","decimals":2,"description":"shares × risk_per_share."},{"name":"direction","label":"Direction","type":"string","decimals":4,"description":"Long when the stop is below the entry, short when above."}],"input_schema":{"type":"object","properties":{"account_size":{"description":"Total trading capital.","type":"number","maximum":1000000000000,"exclusiveMinimum":0,"examples":[50000]},"risk_percent":{"description":"Share of the account you are willing to lose if the stop is hit (commonly 0.5–2 %). Unit: %.","type":"number","maximum":100,"exclusiveMinimum":0,"examples":[1],"x-unit":"%"},"entry_price":{"description":"Planned entry price per share or unit.","type":"number","maximum":1000000000,"exclusiveMinimum":0,"examples":[100]},"stop_loss_price":{"description":"Price at which the trade is exited at a loss; below the entry for a long, above it for a short.","type":"number","minimum":0,"maximum":1000000000,"examples":[95]}},"additionalProperties":false,"required":["account_size","risk_percent","entry_price","stop_loss_price"]},"output_schema":{"type":"object","properties":{"risk_amount":{"description":"account_size × risk_percent / 100.","type":"number"},"risk_per_share":{"description":"|entry_price − stop_loss_price|.","type":"number"},"stop_distance_percent":{"description":"risk_per_share / entry_price × 100. Unit: %.","type":"number","x-unit":"%"},"shares":{"description":"floor(risk_amount / risk_per_share).","type":"integer"},"position_value":{"description":"shares × entry_price.","type":"number"},"position_percent_of_account":{"description":"position_value / account_size × 100 (above 100 % requires leverage). Unit: %.","type":"number","x-unit":"%"},"actual_risk_amount":{"description":"shares × risk_per_share.","type":"number"},"direction":{"description":"Long when the stop is below the entry, short when above.","type":"string"}}},"formula":"risk_amount = account_size × risk_percent/100; risk_per_share = |entry_price − stop_loss_price|; shares = floor(risk_amount / risk_per_share); position_value = shares × entry_price","method":"Fixed-fractional position sizing: the loss at the stop, not the position value, is held to a constant fraction of capital. Slippage, gaps through the stop and commissions can make the real loss larger. Informational mathematics only; not financial advice.","sources":[{"name":"Britannica Money – Calculating position size in trading","url":"https://www.britannica.com/money/calculating-position-size","type":"reference","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Risk return ratio","url":"https://en.wikipedia.org/wiki/Risk_return_ratio","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"50,000 account, 1 % risk, entry 100, stop 95","inputs":{"account_size":50000,"risk_percent":1,"entry_price":100,"stop_loss_price":95},"expected":{"risk_amount":500,"risk_per_share":5,"stop_distance_percent":5,"shares":100,"position_value":10000,"position_percent_of_account":20,"actual_risk_amount":500,"direction":"Long (stop-loss below entry)"},"url":"https://tttkmbb.com/api/v1/calculate/position-sizing?account_size=50000&risk_percent=1&entry_price=100&stop_loss_price=95"},{"name":"Short: 20,000 account, 2 % risk, entry 40, stop 42","inputs":{"account_size":20000,"risk_percent":2,"entry_price":40,"stop_loss_price":42},"expected":{"risk_amount":400,"risk_per_share":2,"shares":200,"position_value":8000,"position_percent_of_account":40,"direction":"Short (stop-loss above entry)"},"url":"https://tttkmbb.com/api/v1/calculate/position-sizing?account_size=20000&risk_percent=2&entry_price=40&stop_loss_price=42"}],"faq":[{"q":"Why is the share count rounded down?","a":"Rounding up would risk more than the chosen percentage; flooring keeps the actual risk at or below the target, which actual_risk_amount reports."},{"q":"What if the position is larger than the account?","a":"A tight stop can imply a position above 100 % of capital; that requires margin and the calculator flags it in the position percentage rather than capping it."}],"tags":["position sizing","position size calculator","risk per trade","stop loss","shares to buy","risk management"],"related":[{"calculator_id":"risk-reward-ratio","reason":"Reward-to-risk of the same entry, stop and target."},{"calculator_id":"stock-profit","reason":"Profit or loss of the position at a given exit price."},{"calculator_id":"max-drawdown","reason":"Largest peak-to-trough loss of an equity curve."}],"links":{"html":"https://tttkmbb.com/investing/position-sizing","markdown":"https://tttkmbb.com/investing/position-sizing.md","json":"https://tttkmbb.com/investing/position-sizing.json","api":"https://tttkmbb.com/api/v1/calculate/position-sizing","schema":"https://tttkmbb.com/api/v1/calculators/position-sizing","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:44:16Z"}