Maximum Lot Size Calculator for MT4/MT5
Info
The Maximum Lot Size Calculator for MT4/MT5 is a Script for MetaTrader 5 that this script calculates the maximum allowable lot size for opening a trading position, utilizing the entirety of the available free margin on the trading account. The computed lot size is displayed in the upper-right corner of the chart for a default duration of 10 seconds.
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 Maximum Lot Size Calculator for MT4/MT5
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 calculates the maximum allowable lot size for opening a trading position, utilizing the entirety of the available free margin on the trading account.
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: Trade Excursion Report: Analyzing Maximum Adverse and Favorable Excursions - another powerful script for MetaTrader 5 traders.
This script calculates the maximum allowable lot size for opening a trading position, utilizing the entirety of the available free margin on the trading account. The computed lot size is displayed in the upper-right corner of the chart for a default duration of 10 seconds. This utility was originally developed for MQL4 and first published in 2026.Also recommended: Risk-Based Lot Size Calculator Script with On-Chart Panel - similar script with strong performance on MetaTrader 5.
Illustration of the Max Lot Script
This script is designed to help traders quickly determine the maximum trade size they can execute based on their current free margin. It simplifies the process of risk management by providing a clear lot size, preventing potential over-leveraging.
You may also like: Contract Sizer: A Risk Management Tool with Ladder, Floor, and Breaker Protections - excellent alternative for script users on MetaTrader 5.
Source Code
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⚠ 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.