Bid Ask Spread Calculation

Bid ask spread calculation is one subtraction, and it decides more of your results than most indicators do. The bid is what a buyer will pay you. The ask is what a seller wants. The gap between them is your cost of entering. This guide covers the arithmetic and how to turn the spread into money. It also covers why spreads widen, and where the cost kills a strategy.

Bid ask spread calculation starts with two prices

Every currency pair shows two prices at once. The bid is the price at which you can sell. The ask, sometimes called the offer, is the price at which you can buy. The ask is always the higher of the two.

This is why a trade starts at a small loss. Buy at the ask and your position values at the bid straight away. It must gain the spread before it breaks even. Nothing has gone wrong; you simply paid the cost of crossing.

The calculation itself is short:

Spread = ask − bid

On EURUSD quoted 1.15335 bid and 1.15351 ask, the difference is 0.00016. A pip sits at the fourth decimal, so that is 1.6 pips. Our guide to the pip in forex trading covers the decimal positions in detail.

Turning the spread into money

Pips only matter once converted to your account currency. Multiply the spread in pips by the pip value for the lot you are trading.

Spread cost = spread in pips × pip value per lot × number of lots

Two mini lots on a 1.6 pip spread costs 3.20 dollars to enter. That figure is paid on every trade, win or lose, which is why it compounds so heavily for anyone trading often. The forex trading lot sizes guide covers the pip values behind those numbers.

Commission sits alongside it. Raw-spread accounts advertise a spread near zero and charge a fee per lot instead. Add the two before comparing accounts. A 0.2 pip spread with a 7 dollar round-turn commission works out near 0.9 pips all-in on a standard lot.

Why the spread moves

Spreads are not fixed on most accounts. They reflect competition for the other side of your trade, and they widen whenever that competition thins.

Session is the biggest driver. The London and New York overlap has the deepest liquidity and the tightest spreads. The gap between the New York close and the Tokyo open is the thinnest stretch of the day, and spreads there can be several times wider.

Scheduled news does it abruptly. Around a rate decision or payrolls print, a pair sitting at 1.6 pips can jump past 8 within seconds. Our forex news factory guide covers planning around those releases.

Volatility generally widens it too, since market makers price uncertainty into the quote. The rollover point at 5pm New York briefly widens almost everything.

Spread by instrument

The pair you choose matters as much as the hour you trade it. EURUSD carries the deepest liquidity in the market and typically the tightest spread. GBPUSD and USDJPY sit close behind.

Crosses cost more, because there is no direct dollar leg. EURGBP and AUDNZD routinely quote two to three times the EURUSD spread. Exotic pairs run wider still, sometimes by a factor of ten.

Gold is the trap for anyone applying forex habits. XAUUSD is quoted in dollars and cents rather than pips, and the spread is far larger relative to a typical move. Read the contract specification before assuming a pip-based cost applies.

The point where spread kills a strategy

Run this calculation before you commit to any short-term method, because it decides viability more reliably than backtest results do.

Take your average winning trade in pips and divide the round-trip cost into it. A 200 pip swing trade paying 1.6 pips gives up under 1%. A 30 pip intraday trade gives up about 5%. A 6 pip scalp gives up more than a quarter.

That last case needs an unusually high strike rate just to break even. It explains why so many scalping systems test well and fail live. Backtests commonly assume one fixed, optimistic spread, while the live account pays a variable one that widens at exactly the moments the system wants to trade.

Two practical consequences follow. Test any short-hold strategy against a pessimistic spread rather than an average one. And restrict trading to the liquid hours, since the same system can be profitable at midday and hopeless at midnight purely on cost.

Reading spread on your own platform

MetaTrader shows bid and ask in the Market Watch window; right-click and enable the Spread column to see it directly. On the chart, only the bid line is drawn by default, so enable the ask line to see both.

Watch it for a few days across different hours before judging an account. A broker advertising an average spread is quoting a number that includes the quiet, deep hours; what matters is the figure during the sessions you actually trade.

Log the spread you paid alongside each trade in your journal. After fifty trades you will know your real cost per trade rather than the marketing figure, and that number belongs in every strategy decision you make.

Common mistakes

Four repeat. Comparing brokers on advertised spread alone tops the list, since it ignores commission and the hours when the quote widens. Backtesting on a fixed optimistic spread comes second, which flatters every short-term result. Third, traders scalp during thin sessions where cost consumes the edge. Fourth, they carry a pip-based cost assumption onto gold or indices, where the contract works differently.

Where to go next

Cost belongs in the same conversation as risk. Read the pip in forex trading for the units, then forex trading lot sizes for pip values, and size trades with the position sizing calculator. For how far pairs typically move before cost is worth paying, see forex pair volatility. For further reading, Investopedia explains the bid ask spread at Investopedia, and the bid-ask spread article on Wikipedia covers the market-making side.

FAQ

How do I calculate the bid ask spread?

Subtract the bid from the ask. On EURUSD quoted 1.15335 bid and 1.15351 ask the difference is 0.00016, which is 1.6 pips because a pip sits at the fourth decimal on that pair.

How much does the spread cost me?

Multiply the spread in pips by the pip value for your lot size. A 1.6 pip spread on one mini lot costs 1.60 dollars, and on one standard lot it costs 16 dollars, paid whether the trade wins or loses.

Why does the spread widen?

Liquidity thins. Spreads widen whenever fewer participants compete for the other side. Expect it outside the London and New York overlap, around news, in volatility spikes and at rollover.

Is a zero spread account cheaper?

Not automatically. Raw-spread accounts charge commission instead, so add both together. A 0.2 pip spread with a 7 dollar round-turn commission works out near 0.9 pips all-in on a standard lot.

Does the spread matter for swing trading?

Far less than for scalping. A 1.6 pip cost against a 200 pip target is under 1%, while the same cost against a 6 pip scalp consumes more than a quarter of the move before price does anything.

Can I avoid paying the spread?

No. It is the price of crossing between buyer and seller, so the practical goal is to reduce it by trading liquid pairs in liquid hours. Trading involves risk, results are not guaranteed, and past performance is not indicative of future results.