Butterfly spread calculator
Pays a small debit for a big payout if the price pins near the middle strike. Enter your strikes and price to see the maximum profit, maximum loss, breakevens, profit chance and expected value.
Leave the price empty to estimate it from implied volatility. Results are per contract (100 shares), held to expiration.
Estimated debit: $133.77 per contract (from implied volatility; type your real price above)
Free, no account. The app adds volatility skew, exit plans, position sizing and a plain-English verdict.
How to use the call butterfly calculator
- Enter the stock's price, the days left until expiration and the implied volatility from your option chain.
- Enter each strike. Then type the price you'd pay per share, or leave it empty for an estimate.
- Add the stock's realized volatility to see expected value: what the trade makes on average if the stock keeps moving the way it has been.
Worked example
Say a stock trades at $100, options price in 25% implied volatility, and the stock has really been moving about 20% a year (its realized volatility). With 30 days to expiration, a call butterfly at strikes 95 / 100 / 105 costs about $1.34 per share, or $133.77 per contract.
- Max profit: $366.23
- Max loss: $133.77
- Breakevens: $96.34 and $103.66
- Profit chance, market-implied: 39.1%
- Expected value with 20% realized volatility: +$29.96 per contract
The expected value is positive here only because the stock is assumed to move less than options price in (20% vs 25%). If it moves more, the same trade can have negative expected value. That gap between implied and realized volatility is what the full app checks first.
What is a call butterfly?
A call butterfly buys one call below the price, sells two calls at the price, and buys one call above. All calls, one expiration.
How it makes or loses money
It earns the most if the price finishes right at the middle strike. Away from the middle, the value fades to zero at either wing. The most you can lose is the debit.
When traders use it
Traders use it when they expect the price to settle near a specific level, often late in the day on expiration.
Profit and loss at expiration
- Max profit: wing width minus the debit, at the middle strike
- Max loss: the debit
- Breakevens: lower strike plus the debit, upper strike minus the debit
The Greeks
| Greek | Sign |
|---|---|
| Delta | ≈ 0 |
| Theta | + near the middle |
| Vega | − |
| Gamma | − |
What to watch out for
- The profit zone is narrow; most of the time it finishes away from the peak.
- Fills matter: three strikes and four contracts make the bid/ask spread expensive.
Questions
What is the max profit on a call butterfly?
Wing width minus the debit, at the middle strike. In the example above that's $366.23 per contract.
What is the max loss on a call butterfly?
The debit. In the example above that's $133.77 per contract.
How do you calculate the breakeven of a call butterfly?
Lower strike plus the debit, upper strike minus the debit. The calculator works it out from your strikes and price.
What does "profit chance" mean here?
It's the market-implied chance that the trade finishes with any profit at expiration, if the stock moves as much as implied volatility prices in. It assumes you hold to expiration and uses one volatility for every strike. A high profit chance doesn't mean a good trade: small, frequent wins can still lose money overall if the losses are large.
What's the difference between implied and realized volatility?
Implied volatility is how much movement option prices assume. Realized volatility is how much the stock has actually been moving. Option sellers tend to come out ahead on average when realized stays below implied, and buyers when it runs above. Expected value in this calculator uses the realized volatility you enter.
Is a call butterfly a good trade?
This calculator can't tell you that, and neither can anyone who doesn't know your account, goals and risk tolerance. It shows the math for the numbers you enter. Whether those numbers hold up depends on the price you actually get, how the stock moves and how you manage the trade.