Spread and Slippage Calculator
Work out what crossing the spread and imperfect fills cost, and how far price must move before a trade is level.
The spread is the most consistently underestimated cost in trading, because it never appears as a line on a statement. It is paid silently at the moment of entry: buy at the ask, and the position is immediately worth the bid. This spread and slippage calculator puts a number on that bid-ask spread cost.
Formula: cost = (spread + entry slippage + exit slippage) x units
Your figures
In units of the instrument — shares, contracts or base units.
Bid-ask spread in price units, from your broker's quote.
Expected adverse fill on entry, in price units.
Expected adverse fill on exit, in price units.
Optional — projects the cumulative drag.
Instrument currency to account currency. 1 when they match.
Results
Execution cost
US$100.00
1.000000 of adverse price movement
- Break-even moveHow far price must travel before the trade is worth nothing.
- 1.00000000
- Break-even move as a percentage
- 2.0000%
- Spread cost
- US$50.00
- Entry slippage cost
- US$20.00
- Exit slippage cost
- US$30.00
- Cost as a share of position value
- 2.0000%
- Position value
- US$5,000.00
- Projected cost over the yearAt the trade frequency entered, on a position of this size.
- US$25,000.00
What this means
Crossing the spread and filling imperfectly costs US$100.00 on this position — 2.0000% of its value. Price has to move 1.000000 in your favour before the trade is worth nothing at all. Repeated at the frequency entered, that is US$25,000.00 a year on execution alone. Note that the break-even move does not shrink with position size — the spread is the same distance whatever you trade.
- Every figure here is broker-specific and must come from your own contract specification or statement. No broker's or venue's figure is preset: where a field opens with a number it is a round illustration to overwrite, because commission, spreads and rates differ by broker, venue, instrument and account tier, and all of them are revised.
- Spreads widen in thin markets and around scheduled news, and slippage appears in the same conditions, so a typical-conditions figure understates the worst case.
- Excludes commission, which is charged separately — the total trading cost calculator combines both.
Execution cost: US$100.00
The link reopens this calculator with the same numbers. Nothing you enter is sent to a server.
Continue with these figures
About the Spread and Slippage calculation
Slippage is its close relative — the gap between the price you expected and the price you got. A slippage calculator has to treat it separately from the spread, because it appears in exactly the conditions where it hurts most: thin markets, fast markets, and the moments after a scheduled release.
Both are measured in price units rather than currency, which is what makes execution cost in trading different from commission. That distinction has a consequence worth understanding: their cash cost grows with position size, but the distance price must travel to overcome them does not shrink at all.
Spread and Slippage formula
price drag = spread + entry slippage + exit slippage
cost = price drag × units × FX
break-even move = price drag
break-even % = price drag ÷ entry price × 100
projected annual cost = cost × trades per year- price drag
- Total adverse price movement, before the market has moved at all.
- slippage
- The difference between the expected fill and the actual one.
- units
- Position size in the instrument's own units.
The three components are all adverse price movements, so they add together in price units and convert to money exactly once. That is why the drag is subtracted from the price move rather than from the resulting profit — doubling the position doubles the cash cost but leaves the break-even distance identical.
That invariance is the important property. A trader who doubles their size to make the spread 'less significant' has not made it less significant at all: the same percentage of every trade is still consumed. The only levers that work are trading a tighter instrument, trading a longer horizon, or trading less often.
The annual projection is where the number usually becomes uncomfortable. A cost that looks trivial per trade, multiplied by a few hundred trades a year, is frequently larger than the account's entire expected return.
Spread and Slippage: a worked example
100 units at 50.00 with a 0.50 spread, 0.20 of entry slippage and 0.30 of exit slippage, traded 250 times a year.
- Price drag0.50 + 0.20 + 0.30 = 1.00
- Spread cost0.50 × 100 = $50.00
- Slippage cost0.50 × 100 = $50.00
- Cost per trade$100.00
- Break-even move1.00, or 2.00% of the entry price
- Projected annually$100 × 250 = $25,000
$100 a trade, and price must move a full 2% just to reach level. Repeated 250 times that is $25,000 a year — on execution alone, before commission.
How to use the Spread and Slippage calculator
- Take the spread from a live quote at the time you actually trade, not from an advertised typical figure — a spread cost calculator is only as honest as the quote you put into it.
- Enter slippage separately for entry and exit; they are often asymmetric, since exits are more likely to be urgent.
- Enter position size in the instrument's units, not in lots or contracts, unless one unit is one lot.
- Add your annual trade count to see the cumulative figure. This is usually the number that changes behaviour.
- Compare the break-even percentage against your average winning trade. If it is a large fraction of it, the strategy has a cost problem rather than a signal problem.
Limitations of the Spread and Slippage calculator
Every calculation makes assumptions. These are the ones that matter here.
- Assumes a constant spread. Real spreads widen at session opens and closes, around scheduled news, and whenever liquidity thins.
- Slippage is entered as an expectation. It is not symmetric in practice — it is worse on stops and on urgent exits than on planned entries.
- Excludes commission and any exchange or clearing fee, which are charged separately.
- Does not model partial fills, where part of an order executes at a worse price than the rest.
Frequently asked questions about Spread and Slippage
Does trading a larger position reduce the cost of the spread?
No, and this is the most common misconception about it. The cash cost rises in exact proportion to size, and the distance price must move to cover it is unchanged. A larger position pays more in absolute terms for the same percentage penalty.
How do I estimate slippage?
From your own fills. Compare the price you intended against the price you got across a sample of trades, separating entries from exits and calm conditions from volatile ones. Broker-published figures are averages that hide the tail, and the tail is where the cost is.
Why is the spread worse for short-term trading?
Because it is a fixed distance paid per trade regardless of how long the position is held. A trader targeting a move ten times the spread pays 10% of the target to enter; one targeting a move a hundred times the spread pays 1%. Holding period, not size, is what dilutes it.
Should I include slippage if I only use limit orders?
Entry slippage can reasonably be zero if you never chase a fill. Exit slippage usually cannot be, because stops execute at market and are triggered precisely when the market is moving against you.
Last reviewed . See our methodology and editorial policy.
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