What is spread in prop trading?
What the bid-ask spread is, why it matters more inside a prop firm evaluation than anywhere else, and how to read measured spread data instead of marketing tables.
What is slippage in prop trading?
What slippage is, why it cannot be read off a price feed, and why Prop Spread leaves it out of every cost it shows.
Slippage is the difference between the price you asked for and the price you were filled at. You click a buy at one number, the order reaches the server a few milliseconds later, and the market has moved a fraction in between. The fill lands on the price that existed when the order arrived, not the one you saw. That gap, positive or negative, is slippage.
Why slippage matters inside an evaluation
Like the spread, slippage is a cost paid at the fill rather than a line on a statement, and inside a prop firm evaluation it spends the same two scarce resources: distance to the profit target and headroom under the drawdown limit. A strategy that enters on fast moves, around news or at session opens will pay more of it than one that enters in quiet conditions, because slippage grows exactly when prices move faster than orders travel.
- Market orders pay slippage in fast markets; limit orders trade it for the risk of not being filled.
- News releases and session opens are where fills drift furthest from the quoted price.
- Stop losses are market orders once triggered, so exits can slip exactly when it hurts most.
Why slippage cannot be read off a price feed
A spread is visible in the quote itself: the distance between bid and ask exists whether or not anyone trades. Slippage only exists at the moment of a real fill, on a real order, at a real size. Measuring it honestly would require placing actual orders at every firm continuously. A price feed alone cannot produce that number, and any site that publishes a precise slippage figure without trading real orders is estimating, whether it says so or not.
How Prop Spread handles it
Prop Spread keeps the two apart by leaving slippage out. Spreads are measured from connected feeds and carry sample counts. Every cost on the site is the measured spread plus the commission the firm publishes, and each one says that slippage is not included, because a figure for your fills would have to be invented.
The practical takeaway is the same one the spread guide ends on: plan with the costs you can see, leave margin for the ones you cannot, and treat any single number that claims to capture both as a starting point rather than a fact.
The costs you can see, live
The module below shows the measurable half of the invoice for EUR/USD at the tracked firms: the currently sampled spread converted to dollars per one-lot round turn, plus each firm's published commission. Slippage is deliberately absent here, because it belongs to your orders, not to a feed.
What one lot costs right now: EUR/USD
FTMO, FundingPips and FundedNext are offline (since 23 Sep and 13 Sep). Not ranked.
Source: Prop Spread's sampling of each firm's live feed, converted to dollars with the commission each firm publishes. Slippage is not included. How the figures are made
Cite this research
Source: Prop Spread Research, "What is slippage in prop trading?", accessed 2026-10-06, https://www.propspread.com/knowledge/guides/what-is-slippage-in-prop-trading
Link to this page when quoting figures, so readers can see the current values and the methodology behind them.
Questions
Is slippage always a cost?
No. A fill can land on a better price than requested, which is positive slippage. In fast markets the drift tends to run against market orders more often than for them, which is why planning treats it as a cost with margin rather than a coin flip.
Can slippage be avoided completely?
Not on market orders in moving markets. Limit orders remove price surprise but add fill uncertainty. The realistic goal is to control when you pay it: calm conditions, sensible sizes, and no market entries into scheduled news unless the strategy prices that in.
Why does Prop Spread leave slippage out?
Because an honest site cannot measure your fills without placing your orders. A slippage figure would be an assumption dressed as a measurement, so every cost here is the measured spread plus the published commission, and it says that slippage is not included.
Next steps
Related research
How drawdown limits actually work
Daily loss limits, overall drawdown, static versus trailing anchors, and why spreads and commissions quietly spend the same headroom your losing trades do.