MT4 vs MT5 for Expert Advisors — Which Should You Choose?
MetaTrader 4 and 5 look similar but are different platforms with different languages, order models and testers. Here is how to choose for a new EA.
For a new Expert Advisor, MetaTrader 5 (MQL5) is usually the better choice: a faster multi-threaded tester with real-tick history, multi-symbol testing, more timeframes, an object-oriented language and native ONNX model support. Choose MetaTrader 4 (MQL4) mainly when your broker, your existing EAs or your clients are tied to MT4. EAs are not interchangeable: the code must be ported between the two.
The main differences at a glance
| MetaTrader 4 (MQL4) | MetaTrader 5 (MQL5) | |
|---|---|---|
| Language | Procedural, C-like | Object-oriented, C++-like (classes, inheritance, templates) |
| Compiled file | .ex4 | .ex5 |
| Account model | Hedging: many independent orders | Netting or hedging, depending on the broker’s account type |
| Strategy Tester | Single-threaded, bar-model based | Multi-threaded, real-tick history, forward testing, multi-symbol, cloud agents |
| Timeframes | 9 standard | 21 standard |
| AI / ML | Needs external bridges (for example DLL or sockets) | Can run ONNX models natively, plus a Python integration package |
| Markets | Mainly forex and CFDs | Forex, CFDs, stocks and futures where the broker offers them |
Account model: hedging vs netting
On MT4, every order is its own position; you can hold a buy and a sell on the same symbol at once. MT5 was built around netting, where all deals on a symbol merge into one position, and later added hedging accounts. Which one you get depends on the broker. This matters for EAs: a grid, a hedge or a multi-order strategy written for hedging can behave differently, or fail, on a netting account. Always confirm the account type before building or buying an EA.
Backtesting
The MT5 tester is the largest practical advantage. It can replay real recorded ticks, test several symbols in one run, use many CPU cores for optimization and offers a built-in forward-testing option. MT4’s tester is simpler and its ticks are generated from bar data, which makes results for scalping and tight-stop systems less reliable. For serious validation see our guide on why EAs fail live.
Porting between MQL4 and MQL5
The two languages share syntax but not the trading API. MQL4 identifies orders by ticket and uses functions like OrderSend, OrderSelect and OrderClose directly. MQL5 separates orders, deals and positions, and indicators return handles that you read with CopyBuffer. Porting is a rewrite of the trading and indicator layers, not a recompile. Plan and budget for it if you need the same strategy on both platforms; a single well-structured codebase can target both, but it has to be designed that way.
Which one should you choose?
- Choose MT5 for new EAs, tick-accurate testing, multi-symbol strategies, portfolio or AI-assisted systems, and non-forex markets.
- Choose MT4 if your broker only offers MT4, you rely on existing MT4 EAs and indicators, or your clients and subscribers use MT4.
- Need both? Build for MT5 first and port a clean, stable version to MT4 afterwards.
Whichever you pick, check that your broker’s account type, symbol specifications and execution model match the assumptions in your EA.
Frequently Asked Questions
Is MT5 better than MT4 for Expert Advisors?
For new projects usually yes, thanks to the faster multi-threaded tester with real-tick history, multi-symbol testing, more timeframes, an object-oriented language and ONNX support. MT4 remains a reasonable choice when your broker, tools or clients depend on it.
Can an MT4 Expert Advisor run on MT5?
No. The platforms use different compiled formats and different trading APIs, so the code has to be ported, not just recompiled.
What is the difference between hedging and netting accounts?
A hedging account allows several independent positions on one symbol, as MT4 always did. A netting account merges all deals on a symbol into one position. Which one you get depends on the broker, and some EA designs only work on hedging accounts.
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