Simulating slippage in the MT5 strategy tester

[FXS London Scalper]

The MT5 tester can model delays, but many people run it with zero latency. That makes results look better than live.

Options:

• Use real ticks if your broker provides them, for realistic spreads.
• Set a delay in the tester settings, for example random delay, to simulate execution lag.
• Add slippage in the EA code in test mode: shift the fill price by a set amount against the trade.

How to pick values: use your live fill data. If market orders slip on average 0.1 pips with a tail of 0.5 pips on news, model that.

A worked example of the effect: an EA making 0.5 pips per trade in testing, with 0.1 pips of slippage on entry and exit, makes 0.3 pips. With 200 trades a month on 1 lot, that's $400 less per month.

Run tests with and without slippage. If the strategy only works without, it's not ready for live.

How do you model execution in testing?