Butterfly Spread Calculator
Use this free butterfly spread calculator to model your low-cost neutral trade before you place it. Enter your three strikes and net debit to instantly see max profit, max loss, both breakeven prices, and a full P&L diagram.
How to use the butterfly spread calculator
Enter your three strikes and net debit above and the calculator updates in real time. Here is what each input does.
Pull current market data (optional)
Type a ticker like AAPL and click Get Price. The calculator fills in the current stock price, dividend yield, and the risk-free rate from the 13-week T-bill, then loads the option chain so you can pick actual strikes and premiums.
Set up your butterfly spread legs
The butterfly spread legs are preloaded for you. Pick each strike, expiration, and premium straight from the option chain, or type your own numbers. The calculator works out implied volatility from the premium you enter, and you can still edit it.
Calculate and read the results
Click Calculate P&L to see max profit, max loss, breakeven, return on risk, and probability of profit, plus position Greeks: delta, gamma, theta, vega, and rho.
Stress test before you trade
Drag the view-date slider to see your P&L curve on any day before expiration, shift implied volatility up or down 50 points, and scan the price-by-date P&L table to see how the trade behaves across scenarios.
This butterfly spread calculator prices each leg with your choice of an American-style binomial model (the default for US equity options) or European Black-Scholes-Merton, and accounts for dividend yield. You can set a per-contract commission, copy a shareable link to your exact setup, download the chart as a PNG, and switch to dark mode.
Understanding the butterfly spread strategy
A long butterfly spread is built from three equally spaced strikes using all calls or all puts. You buy one option at the lower strike, sell two options at the middle strike, and buy one option at the upper strike. The two short options fund a large portion of the two long options, so the net debit is typically very small relative to the potential profit. This gives the butterfly its defining characteristic: a high reward-to-risk ratio when the stock pins at the body strike, at a cost of a very narrow profit zone.
The P&L shape is the classic tent: the position loses the small debit if the stock is outside either wing at expiration, earns maximum profit at the peak of the tent (the body strike), and grades smoothly in between. Because the debit is small, the dollar risk is low. The challenge is accuracy: the stock needs to close very close to the body strike to realize meaningful profit, which makes butterfly spreads more of a precision tool than a probability play.
Placing the body strike
Where you place the middle strike drives the entire trade. Most traders position the body at a nearby support level, at a technical target for the stock, or at a round number where pinning action is historically common near expiration. Some traders place the body slightly above the current stock price to lean bullish, or slightly below to lean bearish, while still keeping a defined downside risk. The calculator helps you preview the breakeven range for any body strike before you commit.
Time decay and expiration timing
Butterfly spreads benefit from time decay as expiration approaches, because the two short options at the body lose value faster than the two long wing options when the stock is near the body. Many traders enter butterfly spreads two to four weeks before expiration to take advantage of the accelerating theta decay in the final stretch without paying for the slow early decay of longer-dated options. Entering too early means paying more premium for time that has not yet decayed.
Butterfly spread example with real numbers
Here is a worked example you can enter directly into the calculator above to see the full P&L diagram in action.
Trade setup: XYZ stock trading at $100.00, target: stock pins at $100
Common butterfly spread mistakes to avoid
A long butterfly has a narrow profit zone and four legs, so most losses come from setup errors rather than the options math. Model your trade in the calculator above, then check it against the mistakes below before you place the order.
Placing the body strike away from your real target
A long butterfly reaches its maximum profit only if the stock pins the body (middle) strike at expiration. If you center the body on a price you do not actually expect, the trade is built to underperform from the start. Place the body where you expect the stock to land, not where the payoff diagram looks best.
Paying too much debit for the wing width
Your max profit is the distance between the body and the wing minus the debit you pay. Overpay, and you shrink the reward while pushing both breakevens closer to the body. Compare the debit to the wing width in the calculator before committing; a butterfly that costs a large fraction of its wing width leaves little room to be right.
Ignoring the two breakevens and the narrow profit zone
Unlike a single long option, a butterfly only profits if the stock finishes between its two breakevens, and that zone is often just a few dollars wide. Check both breakeven points shown above and confirm the stock has a realistic chance of landing inside them by expiration.
Closing too early or holding too long
Most of a butterfly’s value appears in the final stretch as time decay pulls the wings toward the body. If the stock is sitting near the body and the profit is acceptable, it is often worth closing rather than holding for the last cents, because a move away from the body in the final days can erase the gain quickly.
Using illiquid strikes and wide bid-ask spreads
A butterfly has four legs, so every cent of slippage is multiplied across the order, and wide spreads or thin open interest can cost more than the trade is worth on entry and exit. Stick to liquid strikes, and if you want an asymmetric payoff that can be opened for a smaller debit, model a broken wing butterfly instead.
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Butterfly spread calculator FAQ
Common questions about the butterfly spread strategy and how to use this calculator.
A long butterfly spread is a three-leg options strategy where you buy one call at a lower strike, sell two calls at a middle strike, and buy one call at a higher strike, all with the same expiration date and equally spaced strikes. You pay a small net debit upfront. The strategy profits if the stock closes at or near the middle strike at expiration. Maximum loss is limited to the debit paid, and maximum profit is the spread width minus the debit, achieved only if the stock pins exactly at the body strike.
The maximum profit equals the spread width minus the net debit paid, multiplied by 100 per contract. Spread width is the distance between the lower and middle strike (or equivalently between the middle and upper strike). For example, with $10-wide wings and a $2.00 net debit, max profit is $800 per contract ($10.00 – $2.00 = $8.00, times 100). This peak profit is earned only if the stock closes exactly at the middle strike at expiration. Even a small miss reduces the profit proportionally as you move toward either breakeven.
The maximum loss is the net debit paid, multiplied by 100 per contract. This loss occurs if the stock closes at or below the lower wing strike or at or above the upper wing strike at expiration. In both scenarios, all three legs offset each other and the entire spread expires worthless. For example, with a $2.00 net debit, the max loss is $200 per contract. The low debit is one of the butterfly spread’s most attractive features: you can risk a very small dollar amount for a potentially much larger payout if your price target is correct.
A butterfly spread has two breakeven prices. The lower breakeven is the lower wing strike plus the net debit paid. The upper breakeven is the upper wing strike minus the net debit paid. For example, with a $90 lower strike, a $110 upper strike, and a $2.00 net debit, the lower breakeven is $92.00 and the upper breakeven is $108.00. For the trade to be profitable at expiration, the stock must close between those two prices, with maximum profit occurring if it closes exactly at the $100 middle strike.
Both strategies profit when the stock pins near a specific strike at expiration, but they differ in construction and cash flow. A long butterfly spread uses three strikes and is built entirely with calls or entirely with puts. It is a debit trade where you pay a small amount upfront. An iron butterfly uses four legs across both calls and puts, combining a short straddle at the body strike with protective wings, and is a credit trade where you collect premium upfront. The iron butterfly collects more premium and has a somewhat wider breakeven range, while the butterfly spread has a lower upfront cost and a higher reward-to-risk ratio but requires a very accurate price prediction.
Butterfly spreads work best when you have a precise price target for a stock at a specific expiration date and want to express that view with a small upfront cost and defined risk. Common use cases include placing the body strike at a key technical level, a round price where stocks often pin near options expiration, or a post-earnings range where you expect the stock to consolidate. Because the profit zone is narrow, butterfly spreads reward accurate directional and timing analysis more than they reward general neutral positioning. They are less suitable for uncertain or high-volatility environments where the stock is likely to move past the wings.
This calculator is for educational and informational purposes only. Options trading involves substantial risk and is not suitable for all investors. Past performance is not indicative of future results. Always consult a licensed financial professional before making investment decisions.