Quick answer: An Expert Advisor (EA) is an automated trading program for MetaTrader. On MT5 it is a compiled .ex5 file you place in the MQL5/Experts folder, attach to a chart and control through its Inputs tab. It trades by fixed rules while the platform is open.
Key takeaways
- EAs are MetaTrader's built-in way to automate a strategy.
- MT5 EAs use .ex5 files and cannot run on MT4.
- Inputs such as lot size, session hours and drawdown limits change how the EA behaves.
- The Experts tab logs everything the EA does.
- A clear, limited set of inputs is usually safer than hundreds of settings.
Expert Advisors in one paragraph
MetaTrader 5 lets you automate a trading plan with a program called an Expert Advisor. Developers write the logic in MQL5 and compile it into an .ex5 file. You copy that file into MetaTrader, drag it onto a chart and switch on Algo Trading. From then on the EA reacts to each new price tick and sends orders when its rules say so. People often call these programs trading bots.
The files: .mq5 vs .ex5
- .mq5 is the source code. Sellers rarely share it.
- .ex5 is the compiled program MetaTrader runs. This is what you usually receive after buying an EA.
An MT5 EA will not run on MetaTrader 4. If you are still deciding between platforms, read MT4 vs MT5 for automated trading.
Understanding EA inputs
Inputs are the settings you see when you attach an EA or double-click its name on the chart. They are the main way you control risk. Common inputs include:
- Lot size: the size of each position. Start with the minimum your broker allows.
- Session hours: the window when the EA may open new positions, in broker server time. See why session hours matter.
- Max drawdown: a percentage fall from the account peak where new positions stop.
- Equity floor: a dollar level you don't want the account to go below.
- Direction: buys only, sells only or both.
- Strategy settings: the rule parameters. Leave them as delivered unless the documentation says otherwise.
Where EAs live inside MT5
- Navigator → Expert Advisors: the list of installed EAs.
- Chart corner icon: shows whether the EA on that chart is active.
- Toolbox → Experts: the log of every action.
- Algo Trading button: the master switch for all EAs.
Installation takes about ten minutes. Follow our install guide.
How to evaluate an EA
- Clear rules. You should understand, in plain words, when it enters and exits.
- Limits you control. Drawdown and equity limits are a sign the developer thought about risk.
- Honest evidence. Strategy Tester reports and live statements matter more than screenshots. Learn to read them in our backtesting guide.
- Fair pricing model. Compare one-time EAs, subscriptions and copy trading.
- No promises. Anyone guaranteeing returns is a warning sign.
Frequently asked questions
Can I run more than one EA at the same time?
Yes, on different charts. Avoid running two EAs on the same symbol and account unless you understand how their positions interact.
Does an EA keep working if I close MetaTrader?
No. The platform must stay open. Use a VPS if you want it running 24/7.
Can I change an EA's settings after attaching it?
Yes. Double-click the EA name on the chart, open the Inputs tab, change values and click OK.
Is an Expert Advisor the same as a signal service?
No. An EA runs on your own platform and account. A signal service sends trade ideas that you or a copier execute.
Want to see an EA built around limits you control? Remix Ai is an Expert Advisor for MetaTrader 5 with lot size, session hours, drawdown and equity limits. Launch price $199, one-time payment.
Risk disclosure: this article is for education only and is not financial advice. Trading with automated software carries a high risk of loss, and past or simulated results do not predict future results. Remix Ai sells software. We do not manage accounts, offer copy trading or sell trading signals.