Every quoted instrument has two prices: the bid (what someone is willing to pay) and the ask (what someone is willing to sell for). The gap between them is the spread. When you market-buy you pay the ask; when you market-sell you get the bid. Even on a perfect entry you start the trade already in the red by the spread amount.
Spreads vary wildly. Major FX pairs at 8 PM CET are 0.1-0.5 pips. Same pair during a Powell speech can blow to 5+ pips. Cheap-commission products (CFDs) often hide their cost entirely in a fat spread; cheap-spread products usually charge a per-side commission instead. Either way you pay — the question is just where the line item sits.
EURUSD shows Bid 1.08495 / Ask 1.08510. The spread is 1.5 pips. On a 1-lot round-trip that's roughly $15 of cost — before slippage, before commission.
Rough bands traders use: - 0-1 pip on majors — normal liquid hours. Scalpable. - 1-3 pips — getting tight for high-frequency setups. Worth checking your average win in pips first. - 3+ pips — only viable for swing trades that aim for 30+ pip targets, otherwise the broker eats your edge. - Variable spread that widens at news — assume the worst case when sizing, not the marketing-page average.
Spread is the most underrated cost in retail trading. Newer traders look at the per-trade math (`risk = 1R, reward = 2R`) and forget that the broker takes a chunk on entry, then another on exit. A 2:1 R:R setup with 0.5R of spread cost suddenly only delivers 1.5R per win — and the math of expectancy depends on every R you actually keep.
In TradeOnyx you don't model spread separately because the broker already baked it into your fill prices on import. Your Expectancy and Profit Factor in the Overview tab include the cost — there's no "before-spread P&L" in the dashboard, because that number is fiction.
What the dashboard does help with: comparing performance across symbols. Group your trades in the Trades tab by symbol — the ones with the worst expectancy are often the ones with the widest typical spread. That's how you find the products where your edge isn't really beating the broker's tax. Cut those, scale the rest.