Spread Percentage
The bid-ask spread expressed as a percentage of the ask price.
Formula
Variables
Example
(1.1005−1.1000)/1.1005 ≈ 0.045%
How it works
This formula measures how large the bid-ask gap is relative to the price you would pay to buy the currency, which makes it easier to compare spreads across different currency pairs and market conditions. It works by subtracting the bid from the ask to find the absolute spread, then dividing by the ask to express that gap as a fraction of the buying price before converting to a percentage.
When to use it
Use this when comparing trading costs across forex pairs, brokers, or time periods, especially when the same raw spread means different things at different price levels. It is also useful when estimating how much price movement is needed just to cover the spread on a trade.
Worked example, step by step
Ask = 1.2568 Bid = 1.2562 Spread = Ask - Bid = 1.2568 - 1.2562 = 0.0006 Spread% = (Spread / Ask) × 100% Spread% = (0.0006 / 1.2568) × 100% Spread% ≈ 0.0477% Final answer: the spread percentage is about 0.048%
Common mistakes to avoid
- Dividing by the bid instead of the ask
- Forgetting to subtract bid from ask before converting to a percentage
- Confusing the spread percentage with the pip spread or raw price difference
Did You Know?
The spread is the true cost of a “commission-free” currency trade — it is baked into the price.
Share this formula
More in Currency & Forex
View allCurrency Conversion
BasicConvert an amount from one currency to another using the quoted exchange rate.
Inverse Exchange Rate
BasicFlip a quoted rate to express it from the other currency’s point of view.
Currency % Change
BasicThe percentage move in an exchange rate between two points in time.
Cross Rate
IntermediateDerive the exchange rate between two currencies via a common third currency.
Bid-Ask Spread
IntermediateThe gap between the price to buy and to sell a currency — the dealer’s markup.
Pip Value
IntermediateThe monetary value of a one-pip move for a given trade size.