What is Bid-Ask Spread Cost?
The bid-ask spread is the difference between the price at which you can sell (bid) and the price at which you can buy (ask). When you trade, you often buy at the ask and sell at the bid, so the spread is a direct cost. The spread cost in dollar terms is that price difference multiplied by the number of units you trade: (Sell price − Buy price) × Quantity. If sell > buy, the result is a profit; if sell < buy, it is a cost.
How to Use This Calculator
- 1
Enter buy price
The price at which you buy (e.g. the ask price or your entry price).
- 2
Enter sell price
The price at which you sell (e.g. the bid price or your exit price).
- 3
Enter quantity
The number of units (shares, contracts, lots, etc.) you are trading.
- 4
Read the result
Spread cost = (Sell − Buy) × Quantity. Positive means profit from that price difference; negative means cost.
Why Spread Cost Matters
Knowing the spread cost helps you understand the true cost of entering and exiting a trade, compare execution quality across brokers, and size positions so that expected moves are larger than the spread. This calculator works for stocks, forex units, contracts, or any asset where you have a buy price, sell price, and quantity.
Frequently Asked Questions
See the formula above: Spread cost = (Sell price − Buy price) × Quantity. All calculations run in your browser; no data is sent to any server.