FREE TOOL
Bid-ask spread calculator
Enter the bid, the ask and your share count. The calculator shows how wide the spread is, what it costs to buy at the ask and sell at the bid right away, and how far the bid has to rise to get you back to your entry.
The ask must be greater than or equal to the bid, and both must be above zero.
- Spread
- –
- Spread % of mid
- –
- Mid price
- –
- Round-trip cost (buy at ask, sell at bid)
- –
- Bid rise needed to get back to an ask entry
- –
How it is calculated
- Spread = ask − bid
- Mid price = (bid + ask) / 2
- Spread % = spread / mid × 100
- Round-trip cost = spread × shares: what you give up if you buy at the ask and sell at the bid without the price moving
- Bid rise needed = spread / bid × 100
Why it matters for small caps
On a large, liquid stock the spread is often a cent or two, a few hundredths of a percent. On a thin small cap it can be several percent. A 3% spread means the price has to move 3% in your direction before an immediate exit at the bid gets you back to your entry, before any commissions.
The spread also changes during the day: it is usually widest in pre-market and after-hours, and right at the open. The order book panel in Nasdaq Life shows the live spread in dollars and percent next to the Level 2 depth.
FAQ
What is a good spread?
There is no single number. For liquid large caps a spread under 0.1% is common; for small caps several tenths of a percent or more is normal, and wide spreads make short-term trades harder.
Does the calculator include commissions?
No. It only measures the cost of the spread itself. Add your broker's fees separately.