EA costs: spread, commission and swap

EA Trade Tester Demo lab How we test For AI agents

Published 11 November 2026 · methods v2.5 · by TrueTest

Costs decide most backtests. In our own research, 86% of the failed tests whose reasons we listed had costs among the reasons, and our cost study found edges before costs rarely above +0.10 R a trade (340 tests). So the question for any EA is: what share of the stop does one round trip cost?

Test my EA with real costs See a full example first

Drop your .mq5/.mq4 code, a Python bot or an MT5 report on the home page. The first read takes seconds and needs no sign-up; the lab verdict is free too. Only the detailed technical report is paid (the full PDF report is GBP 49). The price shown is the total price: no VAT is added. TrueTest is not VAT-registered in the UK. We read your code as text and never run it as given; an outside AI service drafts the rule card only if you tick the box (see Security). Not financial advice.

What makes up the cost of one trade?

Spread: the gap between buy and sell prices. It is small in the London and New York day and wide around the daily roll-over.
Slippage: the fill is worse than the price you saw. Our lab charges 0.2 pip when the trade opens (gold 2 US cents an ounce).
Commission: on raw-spread accounts, GBP 5 a lot for the round trip in our lab.
Safety margin: our margin on top of the recorded spread: 0.1 pip on most pairs, 0.3 pip on GBPJPY, 48 US cents an ounce on gold.
Swap: the overnight fee for holding past the roll-over; Wednesday night counts 3 times.

How much does the hour change it?

Round trip in pips in our lab (median recorded spread at that server hour + slippage + commission + safety margin):

Symbol	Server 10:00	Server 00:00 (roll-over)	Share of a 15-pip stop at 10:00 / 00:00
EURUSD	1.17	1.57	0.08 R / 0.10 R
GBPJPY	2.75	11.95	0.18 R / 0.80 R

Server time is New York + 7 hours: usually UK time + 2 hours. A GBPJPY trade opened at the roll-over pays 4.3 times the cost of the same trade in the London morning.

Why test again with extra costs?

Your broker can be dearer than ours, and fills get worse when markets move. Our lab runs every trade again with the spread and the commission one and a half times as big, plus 1 pip more when the trade opens (gold 48 US cents an ounce), and any overnight fee you pay one and a half times as big. A result must stay profitable with these extra costs.

What about scalping EAs?

We tested 8,506 short-timeframe scalping settings and 48 published scalping bots with costs. Before costs the best settings made about 0.3 pip a trade; a EURUSD round trip cost about 1.1 pip in that search. All 48 bots lost money in our test once costs were included.

More guides: MT5 Strategy Tester report checker · Free forex EA tester online · Is my EA martingale or grid? How to tell · How many backtests? Overfitting explained · TrueTest vs StrategyQuant, Forex Tester, MT5 · MQL5 / MQL4 EA code checker · Why live results are worse than the backtest · Does my EA repaint or look ahead? · Can a scalping EA make money after costs? · Does my EA make money every year? · Will my EA pass a prop-firm challenge? · What to check before you buy an EA

Questions people ask

My broker has zero commission. Is that cheaper?

Not always: zero-commission accounts usually have a wider spread. Compare the whole round trip in pips.

Does a backtest with a fixed spread show real costs?

Rarely. The spread changes through the day; a fixed spread hides how much the roll-over hours cost.

Can I work out my own costs?

Yes: the trading-cost calculator on our research page runs in your browser and sends nothing.

Are your costs the same as my broker's?

No. They are modelled on one broker's recorded spreads; your broker can be cheaper or dearer. That is why we also test with extra costs.