MT4 vs MT5: Which Platform Should Your EA Target?

By Viprasol Tech Team | Trading Software Development

---

"Just build it for MT4 — my broker supports it and I know the platform."

We hear this almost every week. And about half the time, we push back. Not because MT4 is broken — it isn't — but because the decision affects the quality of your backtests, the accuracy of your risk calculations, whether prop firms will accept your account, and whether the platform you're building on will still be actively supported five years from now.

Here's our honest take, based on migrating dozens of EAs between platforms and building new ones from scratch on both.

---

The State of Play in 2026

MetaQuotes stopped selling new MT4 licenses to brokers in 2022. That's not a rumor — it's confirmed in their official communications. Brokers that have MT4 today can keep running it, but no new broker can launch on MT4. The platform is in maintenance mode.

MT5, meanwhile, receives regular updates. Multi-asset support (stocks, futures, options alongside forex), a proper object-oriented language, a dramatically more accurate strategy tester, and native multi-symbol access in a single EA. This isn't a minor version bump — it's a different development platform.

The practical result: if you're starting a new EA project in 2026, you're almost always better served building on MT5. The exceptions are real, and we'll cover them.

---

The Quick Comparison

---

Where the Differences Actually Hit You

The Backtesting Problem

This one matters more than most traders realize. MT4's Strategy Tester operates on OHLCV bar data. It models the path prices took between the open and close of each bar using a simplified algorithm — which means stop losses, take profits, and pending orders that trigger inside a bar are simulated, not replayed from real market data.

MT5 can use actual historical tick data from MetaQuotes' tick servers. When you run a backtest in "Every Tick Based on Real Ticks" mode, every tick in the database is replayed in sequence, with real spreads and real timing. For a scalping EA where a 3-pip stop matters, the difference between simulated ticks and real ticks is the difference between a meaningful backtest and a fiction.

We had a client come to us with an MT4 EA showing a 2.8 profit factor over three years. Beautiful equity curve. We rebuilt it on MT5, ran it through the real-tick tester with the same parameters, and got a 1.3 profit factor. Still profitable, but the MT4 test had been telling a story the data didn't support. The MT5 test revealed exactly where the EA's weak points were — we fixed two of them and improved the live results significantly.

Multi-Currency EAs

MT4's architecture is single-symbol. An EA attached to a EURUSD chart can't directly read GBPUSD prices without opening that chart separately and using indicator buffers as a communication channel — a fragile workaround that breaks randomly and causes synchronization bugs.

In MT5, pulling data from any symbol is one function call:

// MT5: read any symbol's data from anywhere
double gbpusdClose[];
CopyClose("GBPUSD", PERIOD_H1, 0, 10, gbpusdClose);

MqlRates usdcadRates[];
CopyRates("USDCAD", PERIOD_D1, 0, 30, usdcadRates);

This makes correlation-based EAs, currency basket management, and cross-pair hedging architecturally clean rather than a series of hacks layered on each other.

MQL4 vs MQL5: The Language Difference

MQL4 was designed as a scripting language for individual traders. It works. For simple EAs — single indicator, fixed lot, one pair — the gap isn't large.

For anything complex, the MQL5 object-oriented architecture is a genuine improvement. Here's what a multi-strategy framework looks like in MQL5, which would require messy global variables and manual dispatch in MQL4:

// MQL5: clean class hierarchy for multiple strategies
class CStrategyBase
{
protected:
   string          m_symbol;
   ENUM_TIMEFRAMES m_tf;
   CTrade          m_trade;
   
public:
   virtual bool IsLongSignal()  = 0;
   virtual bool IsShortSignal() = 0;
   virtual void OnBarClose()    = 0;
};

class CEMACross : public CStrategyBase
{
private:
   int m_fastHandle, m_slowHandle;
   
public:
   bool IsLongSignal()  override { /* ... */ return false; }
   bool IsShortSignal() override { /* ... */ return false; }
   void OnBarClose()    override { /* entry/exit logic */ }
};

class CRSIMeanRevert : public CStrategyBase
{
   // Completely independent strategy, same interface
};

This pattern lets us build a single EA that runs multiple strategies across multiple pairs with coordinated risk management — clean, testable, and maintainable. In MQL4, achieving the same thing involves dozens of global arrays and switch statements that become unmaintainable past a certain complexity threshold.

For more on MQL5's OOP capabilities, the MQL5 documentation covers this thoroughly.

---

When MT4 Still Makes Sense

We're not dismissive of MT4. There are legitimate reasons to keep working with it:

Your broker doesn't offer MT5. Some brokers — particularly in certain emerging markets — are MT4-only and have no stated migration timeline. If your broker has no MT5 offering, you have no choice. Check with them before starting development.

You have a profitable MT4 EA that's working. Don't rewrite working code for the sake of platform modernization. If your MT4 EA is live, profitable, and stable, the migration risk outweighs the benefit. The goal is consistent returns, not running the newest platform.

Simple strategy, daily or higher timeframe. An EMA crossover on the daily chart doesn't need real-tick testing. The OHLC simulation in MT4's tester is accurate enough when trades only trigger at bar opens on higher timeframes.

You're learning MQL for the first time. MQL4 is genuinely easier to start with. If you're experimenting, the procedural syntax is more approachable. Once you understand the concepts, MQL5 isn't a difficult step up.

---

When MT5 Is the Right Answer

Prop firm accounts — most serious prop firms run MT5. FTMO, The Funded Trader, Funding Pips — they use MT5 because it has better broker-side risk infrastructure. Your EA needs to run where the funded account lives.

Multi-asset trading — if your strategy involves anything beyond forex and basic CFDs, MT5 is your only option. Index futures, stocks, commodities with realistic tick data — MT4 simply doesn't support these.

Scalping and high-frequency strategies — for any strategy where a 2-3 pip stop matters, you need real tick backtesting. MT4 cannot give you that.

Starting fresh in 2026 — there is no good reason to start a new MT4 project in 2026 unless forced by broker constraints. MetaQuotes' investment is entirely in MT5. New features, better documentation, active developer community — all of that lives in MT5.

---

Migrating an Existing MT4 EA to MT5

We do a lot of these. The key points:

This is not a find-and-replace job. The concepts translate, but the syntax and available functions differ substantially:

A migration for a straightforward single-pair EA typically takes 2–3 days. A complex multi-pair EA with custom indicator buffers and inter-symbol logic takes 5–10 days. We always include re-testing with the real-tick tester as part of the migration — which frequently surfaces edge cases the MT4 tester was hiding.

The other thing we do during migrations: we treat it as an opportunity to improve the risk management. Most older MT4 EAs were written when the community's understanding of drawdown management was less mature. The migration is a good time to add proper daily drawdown guards, lot size normalisation across broker conventions, and a proper error handling layer.

---

Our Recommendation

Build on MT5 for any new project where broker constraints don't force otherwise. The real-tick backtesting alone justifies the decision — you'll have a much clearer picture of how your EA actually performs before risking real money.

For existing MT4 EAs: don't migrate unless you have a specific reason (prop firm requirement, new multi-currency features, wanting real-tick testing). Working and profitable takes priority.

If you want a second opinion on whether your specific situation calls for MT4 or MT5, talk to our team. We'll give you a direct answer, not a sales pitch.

---

See also: Building a Profitable MT5 EA in MQL5 — Full Guide | Prop Firm EA Development

Sources: MetaQuotes MT5 Platform · MQL5 OOP Documentation · FTMO EA Trading FAQ