Last updated:
What Is a Butterfly Spread?
A butterfly spread is a neutral, defined-risk options strategy that involves buying one option at a lower strike, selling two options at a middle strike, and buying one option at a higher strike, all on the same underlying asset and expiration date. The standard long call butterfly uses only call options: you buy the lower strike call, sell two at-the-money calls, and buy the upper strike call. The net result is a position that profits most when the stock closes exactly at the middle strike at expiration and loses only the initial net debit if the stock moves far above or below the outer strikes.
The strategy gets its name from the shape of its expiration payoff diagram, which resembles a butterfly with wings on each side of the central peak. The two outer strikes, sometimes called the wings, define the boundaries of the trade, while the middle strike, called the body, marks the point of maximum profit. The profit zone sits between the two breakeven prices, one on each side of the body, and any close within that range at expiration produces a gain. Because the butterfly spread calculator above shows the exact width of that profit zone before you place the trade, you can evaluate whether the position is realistically sized for the underlying stock's expected behavior.
According to the CBOE options education center, butterfly spreads are one of the most widely used limited-risk neutral strategies among retail and professional options traders alike. Their popularity stems from the combination of a well-defined maximum loss, a potentially high return on risk ratio, and suitability for low-volatility environments where directional bets are unlikely to pay off. As a neutral options strategy calculator, this tool works whether you expect the stock to drift sideways after earnings or simply trade in a tight range into expiration.
How to Construct a Butterfly Spread
Building a valid call butterfly spread requires three equidistant strike prices and four total option contracts. The critical rule is that the distance from the lower strike to the middle strike must equal the distance from the middle strike to the upper strike; the wings must be symmetric. A standard example would be buying the 90-strike call, selling two 100-strike calls, and buying the 110-strike call, creating 10-point wings on each side. Using asymmetric strikes, for instance, 90/100/115, creates a broken-wing butterfly, which is a different strategy with a different risk profile than the standard version computed by this butterfly spread calculator. Running the position through a call butterfly spread calculator before you enter an order is the fastest way to confirm the wings are actually symmetric.
The net debit for a butterfly spread is typically a small fraction of the wing width. If the wing width is $10 and the net debit is $2.50, the maximum risk is $2.50 per share (or $250 per contract), while the maximum reward is $7.50 per share (or $750 per contract). This three-to-one reward-to-risk ratio is achievable only if the stock closes precisely at the middle strike, but even partial profits are earned anywhere within the two breakeven prices. Most traders choose the middle strike at or very near the current stock price to maximize the probability of profiting, though some position the body above or below current price if they have a mild directional bias combined with a low-volatility outlook.
For comparison against other multi-leg strategies, our iron condor calculator computes the equivalent metrics for the four-legged condor structure, which provides a wider profit zone in exchange for a lower return on risk. Explore all investing calculators in our toolkit for additional options, bond, and portfolio tools.
When Is Maximum Profit Achieved?
The butterfly spread max profit is realized only when the underlying stock closes exactly at the middle strike price at expiration. At that point, the two short middle-strike calls expire worthless, generating full retention of the premium received for selling them. The long lower-strike call has an intrinsic value equal to the wing width, while the long upper-strike call also expires worthless. After subtracting the net debit paid to enter, the resulting profit equals the wing width minus the net debit, the maximum the position can ever earn. Confirming both butterfly spread breakeven prices before you place the order matters just as much as knowing the theoretical maximum, since most trades close somewhere inside that range rather than exactly at the body.
In practice, the probability of the stock closing at the exact middle strike is very low. Traders therefore focus on the profit zone; the range between the lower and upper breakeven prices, rather than trying to time an exact pin. Any close within the profit zone generates a partial profit, and the closer the stock is to the middle strike, the larger that partial profit. The payoff table in the butterfly spread calculator above shows exactly how much the position earns or loses at each price level, allowing traders to identify the range of outcomes that produce a meaningful return.
Time decay works in the butterfly spread's favor when the stock is near the middle strike because the two short middle-strike calls lose value faster from Theta than the two long outer-strike calls gain. This positive Theta profile close to the body is a key advantage of the butterfly spread over directional long options strategies, where Theta continuously erodes the position value.
Choosing Strike Prices for a Butterfly Spread
Selecting the right strikes is the most important decision when setting up a butterfly spread strategy. The middle strike should reflect your best estimate of where the stock will be at expiration. It is not simply the at-the-money strike. If you expect a stock currently trading at $100 to consolidate and drift toward $95 over the next 30 days, placing the body of the butterfly at $95 rather than $100 centers the maximum profit zone on your actual price target.
The wing width determines the trade-off between the width of the profit zone and the return on risk. Narrow wings (for example, a 5-point wing on a $100 stock) create a very tight profit zone but a potentially high return on risk because the net debit is small relative to the maximum profit. Wide wings (for example, a 20-point wing) produce a broader profit zone and more forgiveness on price movement, but the net debit is larger and the return on risk is lower. The butterfly spread calculator lets you test multiple wing widths instantly to find the combination that fits your price target, risk tolerance, and return objective.
According to Investopedia's butterfly spread guide, most traders choose wing widths that correspond to standard strike intervals for the underlying, typically $5 or $10 for individual stocks and $25 or $50 for index options. This ensures the position is liquid in both the bid-ask spread and open interest, reducing slippage when entering and exiting the trade. Liquidity is critical for butterfly spreads because the four-legged structure must be executed simultaneously, and poor liquidity can cause the net debit to differ significantly from the theoretical value.
Butterfly Spread vs. Iron Condor: Key Differences
Some traders search for this as an options butterfly calculator rather than a butterfly spread calculator, but the two names describe the identical tool. The butterfly spread and the iron condor are often compared because both are neutral strategies that profit from low volatility and range-bound price action. The fundamental structural difference is that the butterfly uses three strikes and four contracts of a single option type (all calls or all puts), while the iron condor uses four strikes and combines a put credit spread with a call credit spread for a total of four contracts across two option types.
The iron condor is entered for a net credit, you collect premium upfront, while the butterfly spread is entered for a net debit. This means the iron condor's maximum profit (the collected credit) is earned if the stock stays within the inner strikes at expiration, while the butterfly's maximum profit requires a pin at the middle strike. The iron condor has a flat, wide profit zone between its two short strikes, while the butterfly has a peaked payoff that rises sharply toward the middle strike. The butterfly spread typically offers a higher maximum return on risk than the iron condor, but at the cost of a much narrower profit zone requiring the stock to be closer to a specific price at expiration.
In terms of implied volatility sensitivity, both strategies benefit from falling volatility, each has a net short Vega exposure near the center of the profit zone, but the butterfly is more sensitive because it has a larger short gamma position at the middle strike relative to its size. For traders who want the quantitative comparison side by side, our options profit calculator allows you to model individual legs and combine them to build custom strategy payoffs for any options structure. The SEC investor guide to options also provides a plain-language overview of options risks that is valuable reading before using any multi-leg strategy in a live brokerage account.