MT4 vs MT5 for Expert Advisors: which platform should you run?

MetaTrader 4 and MetaTrader 5 look alike, are made by the same company and are offered by many of the same brokers, which is why traders assume a tool for one will run on the other. It will not. The platforms use different programming languages, different compiled file formats and, in some respects, different models of what a position is. This guide explains the differences that matter when you are choosing where to run an Expert Advisor, and what to check before you buy.

The one-sentence answer

If you already trade on a platform you are comfortable with and the tool you want exists for it, stay there. If you are starting fresh, MT5 is the platform that receives new development, has the better strategy tester and is where most new tools are released; choose MT4 only when a specific tool or broker requires it.

File formats are not interchangeable

MT4 tools are written in MQL4 and compiled to .ex4. MT5 tools are written in MQL5 and compiled to .ex5. Neither terminal can load the other's files, and there is no converter. When a product page on this site says “MT4 and MT5”, it means the author ships two separately compiled builds and you receive both. When it says only one, that is the only platform it runs on. The MT4 and MT5 category pages filter the catalogue accordingly.

Hedging versus netting

In MT4 every trade is a separate position. You can hold a buy and a sell on the same symbol at once, and each has its own stop loss and take profit. MT5 accounts come in two modes. Hedging accounts behave like MT4. Netting accounts hold one aggregated position per symbol: a new buy adds to an existing buy, a sell reduces or reverses it, and there is a single stop and target for the whole position.

This matters enormously for grid, basket and multi-entry strategies. An EA written for hedging behaviour will misbehave on a netting account, and vice versa. Product pages on this site state which MT5 account modes a tool supports; if your broker only offers netting accounts, check before buying. You can see your account's mode in the terminal's Navigator → Accounts tooltip or in the Trade tab's account line.

Order and position model

MT5 separates orders (instructions), deals (executions) and positions (the resulting exposure), and adds more pending-order types (buy stop limit, sell stop limit) and fill policies (fill or kill, immediate or cancel, return). MT4 has a simpler model where an order and a position are the same object. For you as a user the practical consequence is that MT5 EAs are more sensitive to broker fill-policy settings, and a tool tested on one broker's symbol specification may need an input changed on another. Authors who sell here document those inputs, and our set-file guide shows how to adjust them.

Strategy tester quality

The MT5 strategy tester is substantially better than MT4's. It supports real tick data from the broker, multi-currency and multi-symbol testing in a single run, multi-threaded optimisation across local cores or a network of agents, and forward testing on a held-out period. The MT4 tester models ticks from one-minute bars unless you import external tick data, tests one symbol at a time and optimises on one core.

This is why most backtest reports from serious authors are now produced in MT5, even for tools that also ship an MT4 build. When you read a report, note which tester produced it and at what modelling quality; our guide Reading backtests critically explains what those numbers mean.

Timeframes, depth of market and instruments

MT5 offers 21 timeframes against MT4's 9, includes a depth-of-market window where the broker supplies one, and supports exchange-traded instruments such as futures and stocks alongside forex and CFDs. If you intend to run an EA on indices, metals or synthetic instruments, check that the tool lists them explicitly; an EA built around forex tick sizes may need adjustments for other symbol specifications regardless of platform.

Performance and resources

MT5 is a 64-bit application and handles many charts and heavy indicators more comfortably. MT4 is 32-bit and can run out of memory with dozens of charts, which is relevant if you run several EAs on a small VPS. Both are light enough for the entry-level VPS plans discussed in Choosing a VPS, but MT5 gives more headroom.

Broker and development support

MetaQuotes stopped issuing new MT4 licences to brokers years ago and focuses development on MT5. Existing brokers continue to offer MT4 because demand is strong, and the terminal still receives maintenance builds, but new features arrive on MT5 first or only. Many independent authors have moved their primary development to MQL5 and ship MT4 builds as a secondary target — some new tools are MT5-only. If you want the widest choice of new releases, MT5 is where they appear.

Prop firms

Most prop firms offer both platforms, but their rule sets — maximum daily loss, restrictions on news trading, hedging rules — apply regardless. A few firms operate netting-only MT5 accounts. Before committing to a firm and a tool, read Prop-firm compatibility and confirm the account mode you will actually receive.

Checklist before buying

1. Open Help → About in your terminal and note the platform and build number.
2. Check the product page lists that platform and a tested build no older than the current public one.
3. For MT5, confirm the tool supports your account's hedging or netting mode.
4. Confirm the symbols you trade are listed, including how the tool handles broker suffixes.
5. If you plan to backtest, note which tester the author's reports come from and whether set files are included.
6. Use Compare to line up alternatives on these points before deciding.

Switching platforms later

If you buy a dual-platform tool, your license covers both builds within the same activation limit, so moving from MT4 to MT5 costs nothing more than a reinstall — follow the installation guide for the new folder structure. If you buy a single-platform tool and later switch, the license does not convert; that is a deliberate reason to favour dual-platform tools when you are undecided.

Whatever you choose, run the tool on a demo account of the same type first. Platform differences are exactly the kind of thing that shows up in a week of demo trading and costs nothing to discover there.