Bid-ask spread calculator measures the gap between what buyers bid and sellers ask.
About this calculator
Bid-ask spread calculator measures the gap between what buyers bid and sellers ask. Enter both quotes from your broker terminal, NSE depth, forex screen, or crypto exchange. You get the absolute spread, spread as a percentage of ask, and the mid price.
Every trade crosses the spread. You buy at the ask and sell at the bid — the difference is an immediate cost before price moves in your favor. Liquid large-cap NSE stocks often show spreads of a few paise; thin small-caps and exotic forex pairs can be much wider.
Spread margin uses ask as the denominator: (Ask − Bid) ÷ Ask × 100. That matches standard market microstructure quoting. Mid price is the average of bid and ask — a reference point, not a price you can usually trade at instantly.
Use with [[stock-profit]] to see round-trip P&L after spread, [[cagr]] for long-term return context, and [[financial-ratios]] when comparing broker execution quality.
Common uses
- Compare bid-ask on Reliance vs a thinly traded small-cap before placing orders
- Check EUR/USD spread on your forex broker vs the interbank quote
- Estimate immediate cost of a round-trip scalp on Nifty 50 constituents
- Teaching — compute spread and margin from sample Level 1 quotes
Frequently asked questions
What is the bid-ask spread on bid 99.994 and ask 100?
Spread = 100 − 99.994 = 0.006. Margin = 0.006 ÷ 100 × 100 = 0.006%. Mid price = 99.997. Enter those bid and ask values to reproduce.
Why is ask always higher than bid?
Sellers want more than buyers offer. The ask is the lowest price a seller will accept; the bid is the highest price a buyer will pay. The gap is where trades happen when someone crosses the spread.
Is a wider spread always bad?
Wider spreads usually mean lower liquidity or higher risk. You pay more to enter and exit. For long-term investors trading liquid stocks, spread cost is often small next to brokerage and taxes.
How is mid price used?
Mid = (Bid + Ask) / 2 is a fair-value reference for charts and index calculations. You still buy at ask and sell at bid in normal market orders.