Slippage is the difference between the price you expected when you placed an order and the price your broker actually filled it at. It happens because there's always a small time gap between the instant you click "buy" or "sell" and the instant that order reaches the market, and price can move during that gap — sometimes in your favor, sometimes against you. It isn't a hidden fee and it isn't automatically a sign your broker is cheating you, but it is a real cost that catches a lot of retail traders off guard, especially around stop losses and high-impact news.
What Slippage Actually Is
When you place an order, you're requesting a price. What you get back is a fill — the price at which the trade actually executed. Under normal, liquid conditions those two numbers are usually identical or close enough not to matter. Under fast-moving or thin conditions, they can diverge, and that gap is slippage. Babypips' Forexpedia definition of slippage frames it simply: an order filled at a price different from the one requested.
Slippage can go either way. Negative slippage means you got a worse price than expected — you bought higher or sold lower than intended. Positive slippage means the opposite: a better fill than you asked for. Some brokers apply these asymmetrically, passing on negative slippage to clients more readily than positive slippage; Babypips also covers this under asymmetric slippage, which is worth understanding when you're evaluating a broker's execution quality.
What Causes Slippage
- Execution latency. The time between submitting an order and the broker's system processing it is never zero. In that window, however small, the market price can move.
- Low liquidity. When there are fewer buyers and sellers at your requested price, the broker has to fill you at the next best available price instead, which widens the gap between what you asked for and what you got.
- Volatility and news events. Fast-moving markets — particularly around scheduled high-impact releases — can see price shift meaningfully between the moment an order is placed and the moment it's filled.
- Broker execution model. How a broker chooses to handle your order when price has moved determines whether you experience slippage or a requote instead — covered in more detail below.
Spread vs Slippage: Two Different Costs
It's easy to lump spread and slippage together since both eat into a trade's outcome, but they work differently. The spread — the gap between the bid and ask price — is a known, direct cost baked into every trade before you even click the button. Slippage is indirect and unpredictable: you don't know its size or direction until the order actually fills. Both tend to widen at the same times, during volatile or illiquid conditions, because liquidity providers pull back and widen their own quotes when they're less certain about fair value — but they're not the same mechanism, and a broker with a tight average spread isn't automatically a broker with low slippage.
Market Execution vs Instant Execution
Brokers generally handle price changes between order and fill in one of two ways. With instant execution, the broker attempts to fill you at the exact price you requested; if the price has moved by the time your order arrives, you get a requote and have to accept the new price or cancel. That gives you price certainty but fill uncertainty — your order might not go through at all during a fast move.
With market execution, the broker fills your order at the best price currently available rather than rejecting or requoting it. That gives you fill certainty — the trade almost always goes through — but price uncertainty, since the fill can land above or below what you requested. Most retail forex brokers today default to market execution, which is exactly why understanding slippage matters: it's the built-in tradeoff for reliably getting your orders filled during fast markets instead of watching them bounce back as requotes.
How Slippage Interacts With Stop Losses
This is where slippage stops being an abstract concept and starts affecting real risk numbers. A standard stop-loss order isn't a guarantee of an exact exit price — once price touches your stop level, it typically converts into a market order and fills at the next available price, not necessarily the price you set. In a fast-moving market, a gap, or a thin session, that fill can land noticeably beyond your intended stop, meaning your realized loss on the trade can exceed what you calculated going in.
Some brokers offer guaranteed stop-loss orders that fill at the exact level regardless of gaps or volatility, usually for a fee or a wider spread — but this isn't universal, so it's worth checking whether your broker offers it if guaranteed execution matters to your strategy. For most traders using standard stops, the practical takeaway is that a stop-loss distance calculated through a risk calculator represents your intended risk under normal conditions, not an absolute ceiling on what a single trade can cost. Reviewing your actual fills over time in a trading journal is the most reliable way to see how much real slippage your own broker and strategy typically produce, rather than relying on assumptions.
Realistic Expectations: Retail Forex vs High-Impact News
During normal trading hours on major, liquid pairs, slippage on a typical market order is usually small under a reasonable broker with decent liquidity. It's not zero, but it's rarely the dominant factor in a trade's outcome. That changes sharply around scheduled high-impact news — events like central bank rate decisions or major employment data can see price gap by a meaningful number of pips within a second or two as liquidity providers pull their quotes and reprice all at once, and execution during that window often comes in worse than requested on both new entries and stop-loss exits.
Checking a live economic calendar before entering or holding a trade through a scheduled release is a simple way to know when that elevated slippage risk is coming, rather than being surprised by it.
How to Manage Slippage Risk
- Use limit orders when the fill price matters more than certainty of execution. A limit order won't fill at a worse price than specified, though it may not fill at all in a fast market.
- Know your broker's execution model. Understanding whether you're on market execution or instant execution sets realistic expectations for requotes versus slippage.
- Be deliberate about holding positions through major scheduled news. Check the economic calendar and decide in advance whether you're comfortable with wider potential slippage on entries and stops during that window.
- Treat calculated risk as an estimate, not a guarantee. Build a small buffer into your risk assumptions rather than treating a stop-loss distance as a hard ceiling on loss.
- Track real fills, not assumed ones. Comparing your planned entry and exit prices against actual fills in a trading journal over time shows you the real slippage pattern on your account.
Slippage is a normal feature of how live markets fill real orders, not a flaw unique to any one broker. The traders who handle it best aren't the ones who avoid it entirely — that's not realistic — but the ones who understand when it's likely to show up, size and plan trades with a small buffer for it, and check their actual results against what they expected using tools like PipDesk's forex profit calculator and the guide on calculating forex profit and loss, rather than assuming every trade fills at the exact price on the chart.