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.
Enter the lower strike
Enter the strike of the long call at the lower wing. This sits below your target price. The distance from this strike to the middle strike is the spread width and determines your max profit potential.
Enter the middle strike
Enter the strike of the two short calls you are selling. This is the body of the butterfly and the peak of the profit tent. Place it at the price where you expect the stock to close at expiration.
Enter the upper strike
Enter the strike of the long call at the upper wing. It should sit the same distance above the middle strike as the lower wing sits below it. Equal wing widths are the standard butterfly structure.
Enter net debit and review
Enter the total net debit paid for the three-leg trade. The P&L diagram updates instantly. Read off your max profit at the body, both breakeven prices, and the small max loss at either wing.
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
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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.