What it is
MQL5 — MetaQuotes Language 5 — is the programming language used to write Expert Advisors, indicators, and scripts for MetaTrader 5. It is more powerful and more flexible than MQL4 but requires rewriting to convert MQL4 code. Code written in MQL5 produces .ex5 compiled files that run exclusively on MetaTrader 5.
How MQL5 differs from MQL4
Object-oriented programming
MQL5 is fully object-oriented — it supports classes, inheritance, and polymorphism in the same way as C++. This makes it better suited for complex, modular EA architectures. MQL4 has limited OOP support.
Multi-threading for Strategy Tester
The MQL5 Strategy Tester can run optimisation tests across multiple CPU cores simultaneously — dramatically faster than MT4's single-threaded optimisation. For developers testing thousands of parameter combinations, this is a significant advantage.
More trading functions
MQL5 exposes more trading functions, order types, and market data than MQL4. For strategies that require complex order management or multi-asset execution, MQL5 is the better environment.
Tick data quality
MT5 backtesting with MQL5 can use real tick data rather than modelled ticks, producing more accurate backtest results — particularly important for scalping strategies where tick-level accuracy matters.
Why it matters
If your EA is built in MQL5 for MetaTrader 5, you need a broker that supports MT5 and a VPS running MT5. Attempting to run an MQL5 EA on MT4 is not possible. Always verify which platform your EA targets before choosing your broker account type.
Common misconceptions
- MQL5 is not automatically better than MQL4 for all use cases. MT4 has a larger EA library, wider broker support, and a more mature ecosystem. MQL5 is better for certain advanced applications — not universally superior.
- You cannot convert MQL4 to MQL5 automatically. The languages are similar enough that experienced developers can port code, but it is a manual process — not a simple file conversion.
The Karnek note
Karnek is read-only monitoring for MetaTrader - it watches every account you run, live on one dashboard, and alerts you the moment something stops. It never trades and never asks for a trading password.
Written and reviewed by the Karnek Research team. Last updated August 2026.
Educational content only - not financial advice. Past performance does not predict future results. Trading carries significant risk.