Position Size Calculator

The provided Pine Script is a custom indicator titled "Position Size Calculator" designed to assist traders in calculating the appropriate size of a trading position based on predefined risk parameters. This script is intended to be overlaid on a trading chart, as indicated by `overlay=true`, allowing traders to visualize and adjust their risk and position size directly within the context of their trading strategy.

What It Does:

The core functionality of this script revolves around calculating the position size a trader should take based on three input parameters:
  1. **Risk in USD (`Risk`)**: This represents the amount of money the trader is willing to risk on a single trade.
  2. **Entry Price (`EntryPrice`)**: The price at which the trader plans to enter the market.
  3. **Stop Loss (`StopLoss`)**: The price at which the trader plans to exit the market should the trade move against them, effectively limiting their loss.
The script calculates the position size using a function named `calculatePositionSize`, which performs the following steps:

  • It first calculates the `expectedLoss` by taking 90% (`0.9`) of the input risk. This implies that the script factors in a safety margin, assuming traders are willing to risk up to 90% of their stated risk amount per trade.
  • It then calculates the position size based on the distance between the Entry Price and the Stop Loss. This calculation adjusts based on whether the Entry Price is higher or lower than the Stop Loss, ensuring that the position size fits the risk profile regardless of trade direction.
  • The function returns several values: `risk`, `entryPrice`, `stopLoss`, `expectedLoss`, and `size`, which are then plotted on the chart.

How It Does It:

  • **Expected Loss Calculation**: By reducing the risk by 10% before calculating position size, the script provides a buffer to account for slippage or to ensure the trader does not fully utilize their risk budget on a single trade.
  • **Position Size Calculation**: The script calculates position size by dividing the adjusted risk (`expectedLoss`) by the price difference between the Entry Price and Stop Loss. This gives a quantitative measure of how many units of the asset can be bought or sold while staying within the risk parameters.

What Traders Can Use It For:

Traders can use this Position Size Calculator for several purposes:
  • - **Risk Management**: By determining the appropriate position size, traders can ensure that they do not overexpose themselves to market risk on a single trade.
  • - **Trade Planning**: Before entering a trade, the script allows traders to visualize their risk, entry, and exit points, helping them to make more informed decisions.
  • - **Consistency**: Using a standardized method for calculating position size helps traders maintain consistency in their trading approach, a key aspect of successful trading strategies.
  • - **Efficiency**: Automating the calculation of position size saves time and reduces the likelihood of manual calculation errors.

Overall, this Pine Script indicator is a practical tool for traders looking to implement strict risk management rules within their trading strategies, ensuring that each trade is sized appropriately according to their risk tolerance and market conditions.
Release Notes:
Updated to have only position size show in indicator status line
Release Notes:
Added color to numerator and denominator
Added denominator in plot
Release Notes:
Simplified calculation by using math.abs()
Open-source script

In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.


The information and publications are not meant to be, and do not constitute, financial, investment, trading, or other types of advice or recommendations supplied or endorsed by TradingView. Read more in the Terms of Use.

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