# RavingDesk Position Size & Risk Planner

> Size a long or short paper trade from your risk budget, stop, target and round-trip fee. Calculates how many units fit a fixed risk budget (account × risk %) between entry and stop, including an estimated round-trip fee, plus the loss at the stop, the profit at the target, reward/risk and a price-move map. It is the risk planner of the RavingDesk paper-trading workspace; it does not place orders.

Part of usefulweb.site (https://usefulweb.site/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://ravingdeskpositionsize.usefulweb.site/ (interactive tool at https://ravingdeskpositionsize.usefulweb.site/tool)
- JSON API: POST https://ravingdeskpositionsize.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://ravingdeskpositionsize.usefulweb.site/api/v1/tool)
- OpenAPI: https://ravingdeskpositionsize.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://ravingdeskpositionsize.usefulweb.site/mcp - tool `ravingdesk_position_size`

## Inputs
- side (select): Direction
- account (number, required): Account size - Paper account value in your account currency.
- riskPercent (number, required): Risk per trade
- entry (number, required): Entry price
- stop (number, required): Stop price - Below entry for a long, above entry for a short.
- target (number, required): Target price - Above entry for a long, below entry for a short.
- fee (number): Estimated round-trip fee - Entry plus exit fee in account currency; it is taken out of the risk budget.

## Method
- Risk budget = account × risk % ÷ 100. The estimated round-trip fee is subtracted first, so quantity = (risk budget − fee) ÷ |entry − stop|.
- Loss at the stop = quantity × |entry − stop| + fee (equals the risk budget); profit at the target = quantity × |target − entry| − fee; reward/risk = profit ÷ loss.
- For a long the stop must be below and the target above the entry; for a short it is the other way round.
- The move map shows the gross profit or loss of the planned quantity at −10 %, −5 %, 0, +5 % and +10 % from the entry, without fees.
- Quantities are fractional; round down to whole units or lot sizes yourself. Stops are not guaranteed fills: gaps and slippage can make the real loss larger.

## Limits
- Paper-trading calculation for education and planning only. It is not investment, tax or legal advice, uses only the numbers you enter and never places an order.