Bid-Ask Spread Calculator
Calculate the bid-ask spread in dollar terms and percentage, find the midpoint price, and see the effective cost of a round-trip trade.
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How to use this calculator
The spread is the difference between the lowest ask and highest bid price. Spread % is typically expressed relative to the ask. A round-trip trade costs the full spread.
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Enter the current bid price (the highest price a buyer will pay).
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Enter the current ask price (the lowest price a seller will accept).
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The calculator shows the absolute spread, percentage spread, midpoint, and round-trip trading cost.
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Use the interpretation to assess market liquidity before placing a market order.
Frequently asked questions
What does the bid-ask spread represent?
The spread is the transaction cost embedded in the market. When you buy at the ask and later sell at the bid, you lose the spread. On a $50 stock with a $0.25 spread, you need the stock to rise $0.25 just to break even. Tight spreads mean lower implicit trading costs.
How does the spread affect frequent traders?
Significantly. A day trader making 10 round trips per day on a stock with a 0.1% spread pays 1% in daily spread costs alone. Over a year of trading days, this compounds to substantial losses even before commissions. Wide-spread securities are particularly costly for active trading.
Should I use market orders or limit orders when the spread is wide?
For wide spreads, use limit orders — you specify your price and wait for the market to come to you. Market orders in illiquid securities can execute at far worse prices than expected (slippage). The risk of limit orders is non-execution if the market moves away before your order fills.
What causes spreads to widen?
Low trading volume, high uncertainty/volatility, news events, pre/post market hours, small-cap or penny stocks, and low dealer competition all widen spreads. Spreads on major currency pairs are widest during Asian/Pacific session when major market makers are less active.
Understanding bid-ask spreads in trading
Market makers and spread economics
Market makers provide liquidity by continuously quoting bid and ask prices. Their profit is the spread — they buy at the bid and sell at the ask. Tighter spreads arise when many market makers compete; wider spreads when liquidity is thin or uncertainty is high. For investors, the spread is an invisible fee paid every time a trade is executed at market price.
Spreads across asset classes
Major currency pairs (EUR/USD): 0.5–2 pips (0.005–0.02%). US large-cap stocks: $0.01 on $50 stock = 0.02%. Small-cap stocks: 0.5–3%. Emerging market ETFs: 0.1–0.5%. Corporate bonds (OTC): 0.25–2%. Cryptocurrency: 0.1–1%+ depending on exchange and pair. The less standardized and less liquid the asset, the wider the spread.
Total transaction cost: spread + commission
Commission-free brokers eliminated explicit commissions but earn revenue through the spread (payment for order flow). "Free" trades are not cost-free if your order fills at a worse price than the midpoint. The total transaction cost = spread cost + commission. For small trades, the spread dominates; for large trades on liquid securities, the spread is trivial and commissions (if any) matter more.
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