Risk-Based Lot Size Calculator Script with On-Chart Panel
Info
The Risk-Based Lot Size Calculator Script with On-Chart Panel is a Script for MetaTrader 5 that this script answers one question before every trade: how many lots should i open so that a stop loss hit loses exactly the percentage of my account that i decided to risk. You drop it on a chart, set the risk percent and the stop loss distance in points, and it shows the lot size in a panel on the chart.
Usage
This tool is typically used for enhancing chart analysis and decision making.
Platform
This Script works exclusively on MetaTrader 5 (both build 600+ and newer versions).
Setup
Place the downloaded file in MQL5/Scripts folder via File ? Open Data Folder in MetaTrader 5.
How to Install and Use Risk-Based Lot Size Calculator Script with On-Chart Panel
1. Installation: Move your script file into the MQL/Scripts directory and restart the platform.
2. Execution: Drag the script onto a chart; it will perform a one-time action, such as closing all open orders or clearing chart objects.
3. Editing: Use MetaEditor (F4) to modify code, click "Compile," and verify no errors appear in the terminal before running.
4. Removing: Scripts stop automatically, but you can remove them manually by right-clicking the chart and choosing "Remove Script."
Frequently Asked Questions
Q: How are scripts different from EAs? A: Scripts execute a single action and then stop; EAs monitor the market and trade continuously.
Q: Can I assign a hotkey to a script? A: Yes, right-click the script in the Navigator, select "Set Hotkey," and define your preferred keyboard shortcut.
Q: Why did my script stop? A: Scripts are designed to stop immediately after finishing their programmed command; this is normal behavior.
What this tool does
This script answers one question before every trade: how many lots should I open so that a stop loss hit loses exactly the percentage of my account that I decided to risk.
Typical Use Case
This Script excels in automated trading and technical analysis on MetaTrader 5.
Compatible Platform & Setup
This Script works on MetaTrader 5. Place the file in the MQL5/Scripts folder and restart the terminal.
Description & Settings
Related: Contract Sizer: A Risk Management Tool with Ladder, Floor, and Breaker Protections - another powerful script for MetaTrader 5 traders.
This script answers one question before every trade: how many lots should I open so that a stop loss hit loses exactly the percentage of my account that I decided to risk?Also recommended: Correlation-Aware Lot Size Calculator for MT4/MT5 - similar script with strong performance on MetaTrader 5.
You drop it on a chart, set the risk percent and the stop loss distance in points, and it shows the lot size in a panel on the chart. The calculation uses OrderCalcProfit(), so the tick value, the contract size and the account currency are handled by the platform. It works on forex pairs, gold, indices and crypto without any symbol specific setting.
How the lot is calculated
The script takes the risk base (equity, balance or free margin) and multiplies it by the risk percent to get the amount of money you accept to lose. It then asks the platform how much 1 lot would lose if the price moves from the entry price to the stop loss, and divides the two numbers. The result is rounded down to the volume step of the symbol and kept between its minimum and maximum lot, so the real risk never goes above what you asked for.
If the exact lot is below the broker minimum, the panel shows a warning, because the minimum lot risks more than you asked. A second warning appears when the free margin is not enough for the calculated lot.
Input parameters
Risk per trade, % of the base below
- the percent of the risk base you accept to lose if the stop loss is hit (default 1.0).
Risk base
- equity, balance or free margin.
Direction
- true for a buy, false for a sell. The entry price is the current Ask for a buy and the current Bid for a sell.
Stop loss distance, in points
- distance between the entry price and the stop loss (default 200).
Take profit as a multiple of risk
- optional. Enter 2.0 to see the take profit level at 2R. Leave 0 to hide it.
How to use
Copy RiskLotCalculator.mq5 to the MQL5 Scripts folder and compile it in MetaEditor.
Drag the script from the Navigator onto the chart of the symbol you want to trade.
Set the inputs and press OK.
Read the lot size, the money at risk and the margin needed in the panel. Press Close to remove the panel.
The script does not open, modify or close any trade. It only reads the account and symbol information and draws the panel.
You may also like: Risk-Based Position Sizing Calculator - excellent alternative for script users on MetaTrader 5.
Source Code
#property copyright "RobotFX"
#property link "https://robotfx.org"
#property version "1.02"
#property description "This code is educational. Feel free to use, modify and upgrade as you wish. Visit ROBOTFX.ORG for professional trading tools"
#property script_show_inputs
enum ENUM_RISK_BASE
{
RISK_EQUITY = 0,
RISK_BALANCE = 1,
RISK_FREE_MARGIN = 2.......
⚠ Limitations & Risk Warning
- This tool is provided for educational and testing purposes only.
- Past performance does not guarantee future results.
- Trading involves substantial risk of loss. Use on a demo account first.
- Results may vary depending on market conditions, broker, and settings.
- We recommend thorough backtesting and forward testing before using with real funds.