Do MT4 EAs run on MT5?

Not without porting. MQL4 and MQL5 are different languages. Automated converters exist but rarely produce reliable code. A proper port means rewriting under MT5 conventions.

Why do so many traders still use MT4?

MT4 has accumulated a massive EA library and community since around 2005. Many commercial EAs are only available for MT4. The simpler hedging account model — multiple independent trades on the same symbol — is also more intuitive for certain multi-EA setups.

Which platform should I use for new EA development?

MT5. MetaQuotes is no longer developing MT4. MT5 has superior backtesting tools, genuine tick-data downloads, a multi-threaded optimiser, and an active MQL5 developer community.

MT4 vs MT5 for Algo Trading: What EA Developers Need to Know

Why platform choice matters more for EA traders than for manual traders

For a manual trader, MT4 vs MT5 is a question of habit and chart comfort. For an EA trader, the platform decides backtest quality, execution architecture, multi-symbol capability, and the long-term viability of the code. Anyone developing today is making a decision that will have consequences for years.

At a glance

| Criterion | MT4 | MT5 | |---|---|---| | EA language | MQL4 | MQL5 | | Tick data | Broker-supplied, limited | Genuine tick download, high quality | | Backtesting | Single-threaded, slow | Multi-threaded, dramatically faster | | Account model | Hedging (multiple trades per symbol) | Netting (default) + hedging option | | Multi-asset | Limited (no native futures) | Stocks, futures, options, forex | | Development status | Discontinued (no active updates) | Actively developed | | Broker availability | Very high (nearly all forex brokers) | Growing rapidly, still below MT4 | | Community / EAs | Huge legacy library | Growing, more modern library |

Account model: the most overlooked difference

This is the point that surprises most switchers.

MT4 — hedging model: you can hold multiple independent long and short positions on the same symbol simultaneously. Each position has its own SL, TP, and trade history entry. For multi-EA setups where EA A is long and EA B is short on EURUSD, this is intuitive.

MT5 — netting model (default): positions on the same symbol are merged into a single net position. A long and a short on EURUSD partially cancel each other out. This changes how EAs must implement their position management logic.

MT5 with hedging account: since MT5 build 1755+, many brokers offer MT5 accounts in hedging mode. This resolves the problem — but check whether your broker supports it. Our broker reviews document which account models each provider offers on MT5.

MQL4 vs MQL5: what changes when developing?

MQL5 is very similar to MQL4 but not identical. The key differences for EA developers:

Position management: in MQL4 you work with OrderSend(), OrderSelect(), and a simple order pool. In MQL5 there is PositionSelect(), PositionGetDouble(), and the CTrade class from the standard library — more powerful, but structured differently.

Type strictness: MQL5 is more strictly typed. Code that works in MQL4 with implicit casts will not compile in MQL5 without explicit conversions.

Object model: MQL5 has a fully object-oriented standard library (CTradeClass, CIndicator, etc.) that considerably simplifies professional EA design.

Indicator buffers: indicators work differently in MQL5 — iCustom returns a handle rather than a direct array value. The switch takes time to internalise but is more consistent once learned.

Backtesting: MT5 is clearly superior

This is the uncontested advantage of MT5 for EA developers.

Genuine tick download: MT5 downloads tick-by-tick data directly from the broker. Quality depends on the broker but is significantly better than MT4's interpolated ticks for most modern MT5 brokers.

Multi-threaded optimisation: MT5 uses all available CPU cores for optimisation runs. What takes hours in MT4 is done in minutes in MT5.

Walk-forward analysis: MT5 includes a built-in walk-forward optimiser. In MT4 you need third-party tools.

For rigorous backtesting and forward-testing, MT5 is the considerably better platform.

Broker availability: MT4 is still more widespread

This remains the strongest practical argument for MT4. Nearly every forex broker offers MT4; MT5 availability is lower but growing steadily. Among the providers we have reviewed — including IC Trading, RoboForex, and BlackBull — most now offer both platforms.

For new setups where you have flexibility, choosing a broker with full MT5 support is the right long-term move.

VPS and runtime environment

Both platforms run on a Windows-based VPS. MT5 is more resource-intensive than MT4; with multi-chart setups running many EAs, factor this into your RAM planning. A practical rule of thumb: MT4 with 5–10 active charts is comfortable at 2 GB RAM; a comparable MT5 setup wants closer to 4 GB.

Which platform for which use case?

Choose MT4 if:

You are running a proven commercial EA that is only available for MT4.
Your broker only offers MT4.
You have a large existing MQL4 codebase you are not ready to port.

Choose MT5 if:

You are developing something new or porting existing strategies.
You run serious walk-forward tests and multi-pass optimisations.
You want to trade multi-asset or futures.
You want platform security for the long term.

Conclusion

MT4 is the legacy; MT5 is the future. For all new EA development and for serious backtesting, MT5 is the better choice today — superior test infrastructure, better tick data, and active ongoing development. The only substantive argument for MT4 is the legacy EA library and broader broker availability. Anyone active in algo trading for the long term will eventually need to port their strategies to MT5.