Butterfly Spread Calculator

Calculate maximum profit at the body, maximum loss, both break-evens and return on risk for a long or short butterfly.

A butterfly is three strikes and four contracts: one at the lower wing, two at the body, one at the upper wing, all of the same type and the same expiry. Bought, it pays most when the underlying finishes at the body and costs a limited amount everywhere else. Sold, the shape inverts. The two contracts at the middle strike are what give the payoff its peak, and they are also why this butterfly spread calculator counts one position as four option contracts rather than three.

Formula: max profit = wing width x multiplier - net debit paid

Your figures

Currency

Position

Option type

All three strikes are the same type. With equal wings calls and puts give the identical payoff; with a broken wing they do not.

Lower wing strike

One contract at this strike.

Body strike

Two contracts at this strike — the body is traded twice, against one at each wing.

Upper wing strike

One contract at this strike. It need not be as far from the body as the lower wing.

Net premium per share

All four contracts together, per share rather than per contract. Enter it positive; the selector below says whether it is paid or received.

Premium paid or received

A symmetric butterfly is bought for a debit and sold for a credit. Only a broken-wing structure can be the other way round.

Number of contracts

One contract means one whole butterfly: four option contracts, because the body is traded twice.

Shares per contract

From your own contract specification. 100 on standard US equity options.

Commission per contract

Per option contract, charged on entry and exit. A butterfly has four legs, so eight charges in all.

Underlying price at expiry

Optional. Values the butterfly at this price, at expiry. Leave it blank to skip that.

Results

Maximum profit

US$350.00

at the US$100.00 body strike, against US$150.00 at risk

Maximum lossThe worst of the three strikes, which is where the payoff is at its lowest.: US$150.00
Result at the body strikeIf the underlying finishes exactly at US$100.00.: +US$350.00
Upper break-evenBetween the body and the upper wing, where the payoff passes through zero.: US$103.50
Lower break-evenBetween the lower wing and the body, where the payoff passes through zero.: US$96.50
Return on riskMaximum profit divided by maximum loss. A ratio between the two extremes, not a likelihood that either is reached.: 233.33%
Result beyond the wingsThe payoff is flat outside the wings, and with equal wings it settles at the same figure on both sides.: -US$150.00 below · -US$150.00 above
Wing widthsEqual wings, so the payoff is symmetrical about the body.: US$5.00 lower · US$5.00 upper
Net debit paidAcross every butterfly, after commission.: US$150.00
Payoff rangeThe full span from the worst strike to the best. Maximum profit and maximum loss sum to it, commission included.: US$500.00
Option contracts tradedFour per butterfly — one at each wing and two at the body.: 4
Shares controlledContracts multiplied by the shares each contract controls. Every cash figure scales with this, not with the number of legs.: 100
Result at the price enteredAt expiry, if the underlying finished exactly there.: +US$350.00

What this means

A long call butterfly buys one contract at each wing against two sold at the body, and here that is 1 butterfly with wings of US$5.00 and US$5.00 either side of the US$100.00 body, opened for a debit of US$150.00 after commission over 100 shares. The payoff is flat outside the wings and slopes at one point per point between them, so the three strikes are the only prices that need evaluating: -US$150.00 at US$95.00 and anywhere below, +US$350.00 at US$100.00, and -US$150.00 at US$105.00 and anywhere above. The largest and smallest of those three are the maximum profit of US$350.00 and the maximum loss of US$150.00, and they sum to US$500.00 — the span between them.

Every figure here is an at-expiry figure, where each leg is worth its intrinsic value and nothing else. Before expiry the legs still carry time value, so the position can quite legitimately trade outside the maximum profit and maximum loss shown, and closing early gives a different result.
Commission is charged as eight fills: four legs, each opened and closed. A leg left to expire worthless costs nothing to close, so this overstates the cost rather than understating it.
American options can be assigned before expiry. A short leg assigned while the long leg is still open leaves a different position from the one priced here until it is resolved, and the risk in the meantime is not what these figures describe.
Assumes all four contracts share the same underlying and the same expiry, and that the body is exactly twice the size of each wing. Any other ratio is a different structure from the one priced here.

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About the Butterfly Spread calculation

The structure is usually taught with symmetric wings, where a handful of tidy formulas apply: maximum profit is the wing width less the debit, maximum loss is the debit, and the two break-evens sit that same distance either side of the body. Those formulas stop being true the moment the wings are unequal, which is exactly when a butterfly becomes interesting — and exactly when a calculator that only knows the textbook case starts producing confident wrong answers.

This one evaluates the payoff from the leg ratio itself, so a broken-wing butterfly is handled on the same footing as a symmetric one. It reports butterfly option profit and loss at expiry: the maximum profit and maximum loss, the result at the body strike, the flat result beyond each wing, both break-evens where they exist, the return on risk and the full span of the payoff, for a long or short butterfly built from calls or from puts.

Butterfly Spread formula

one contract at each wing, two at the body
  L = lower wing strike, B = body strike, U = upper wing strike

structure value per share at expiry:
  calls: max(P−L, 0) − 2 × max(P−B, 0) + max(P−U, 0)
  puts:  max(L−P, 0) − 2 × max(B−P, 0) + max(U−P, 0)

profit per share = ±value(P) + cash at entry
  + for a long butterfly, − for a short one
  cash at entry = credit received, or −debit paid

the payoff is flat outside the wings and straight
between the strikes, so only L, B and U need evaluating

shares controlled = contracts × shares per contract
commission        = rate per contract × 4 legs × contracts × 2

max profit = best of the three × shares − commission
max loss   = −worst of the three × shares + commission

break-evens = zero crossings on the two sloping segments
return on risk = max profit ÷ max loss × 100

L, B, U: Lower wing, body and upper wing strikes, in ascending order. The body is the strike traded twice.
P: The underlying price at expiry — the one number the whole payoff is a function of.
structure value: What the four contracts are worth together at expiry, before the premium paid or received is applied.
cash at entry: The net premium, signed: positive if it was received, negative if it was paid.
wing width: Body less lower strike on one side, upper strike less body on the other. Equal wings make a symmetric butterfly.
broken wing: A butterfly whose wings are unequal, which leaves the payoff away from zero on one side rather than flat at it.

Writing the value straight from the leg ratio, rather than from a case analysis of where price finished, is what lets one expression cover every butterfly. The three terms are the three contracts with their signs and quantities, and the max functions handle the ranges automatically: each term switches on when price passes its strike and contributes nothing before that. No branching is needed because the arithmetic already contains it.

The payoff needs evaluating at only three prices, and the reason is geometric. Between adjacent strikes the slope is exactly one point of profit per point of underlying — one contract's worth — and beyond the outer strikes it is flat, because every option is either fully in or fully out of the money and one more point moves nothing. A function that is straight between three knots and level outside them takes its highest and lowest values at those knots. Searching for the extremes is unnecessary; the calculator simply looks at all three.

Broken wings are where the general treatment earns its place. Write wL for the lower wing and wU for the upper. A call butterfly is worth wL at the body and wL − wU everywhere above the upper strike; a put butterfly is worth wU at the body and wU − wL everywhere below the lower strike. When the wings match, both of those tails are zero, the payoff outside the wings settles flat at minus the debit, and calls and puts give the identical picture — which is precisely why the symmetric case hides the distinction so completely.

When the wings do not match, one tail is not zero, and its sign decides everything about the structure. A call butterfly with a wider upper wing carries extra risk above the upper strike, and it is that risk which the market pays for — which is how such a butterfly can be opened for a credit rather than a debit. The same structure with a wider lower wing gives up its tail on the far side instead. A broken wing moves risk from one side of the body to the other; it does not remove it, and the two tail figures the calculator reports are where it has gone.

That is also why a butterfly break-even is found by interpolation rather than by adding the premium to a strike. Each sloping segment runs between two known profit figures, so the crossing is a straight-line solve on that segment. A symmetric long butterfly has one on each side, equally far from the body. A broken-wing structure opened for a credit frequently has only one, because it cannot lose money on the side the credit already covers, and the calculator reports the absent side as none rather than as a price the payoff never reaches.

Direction and premium type are separate inputs deliberately, because their combinations are not all sensible and the calculator can only say so if it is told both. A symmetric butterfly is bought for a debit and sold for a credit; a long one entered for a credit would be a position that could not lose at any price, which no market offers. Rather than printing that impossible result, the calculator names the two fields most likely to have been confused — the premium's sign and the long or short selector.

Maximum profit and maximum loss sum to the payoff range, the full span between the best and worst of the three strike values, commission included. It is the same check as the width identity on a vertical, generalised to a shape with three knots instead of two, and it is worth running on any butterfly whose wings are not equal.

Butterfly Spread: a worked example

A long call butterfly: buy the 95 call, sell two 100 calls, buy the 105 call for a net debit of 1.50 a share, four contracts of 100 shares, commission 0.65 a contract.

Wing widths100 − 95 = 5.00 lower, 105 − 100 = 5.00 upper
Option contracts4 butterflies × 4 = 16
Shares controlled4 × 100 = 400
Commission, round trip0.65 × 16 × 2 = 20.80
Net debit paid1.50 × 400 + 20.80 = 620.80
Value at 95 and below0 − 0 + 0 = 0, so −1.50 a share
Value at 1005.00 − 0 + 0 = 5.00, so +3.50 a share
Value at 105 and above10.00 − 10.00 + 0 = 0, so −1.50 a share
Maximum profit3.50 × 400 − 20.80 = 1,379.20
Maximum loss1.50 × 400 + 20.80 = 620.80
Payoff range5.00 × 400 = 2,000.00 = 1,379.20 + 620.80
Break-evens95 + 1.50 = 96.50 and 105 − 1.50 = 103.50
Return on risk1,379.20 ÷ 620.80 = 222.16%
Result at 102.00(7.00 − 4.00 − 1.50) × 400 − 20.80 = 579.20

1,379.20 at the 100 body against 620.80 at risk, which is the whole debit including commission, and the two sum to the 2,000.00 span. The position is level at 96.50 and 103.50, and anywhere outside 95 to 105 it settles flat at the same 620.80 loss. A finish at 102.00 — two points past the body, still inside the upper break-even — returns 579.20.

How to use the Butterfly Spread calculator

Set Position to long if you are buying the wings and selling the body, or short if you are selling the wings and buying the body. It decides the sign of the whole payoff, so it matters more than any other field here.
Choose the option type. All three strikes are the same type; with equal wings calls and puts give the identical payoff, and with a broken wing they do not, which is why the choice is asked rather than assumed.
Enter the three strikes in ascending order. The body is the strike traded twice — one contract at each wing against two at the middle — and it does not have to sit halfway between them.
Enter the net premium per share for all four contracts together, as a positive figure, then use the premium selector to say whether it was paid or received. Separating the two removes any need to sign the premium yourself.
Set the number of contracts to the number of whole butterflies. One contract means four option contracts, because the body is traded twice, and the result panel reports that figure back.
Take the shares per contract from your own contract specification, and enter your own commission per contract. Commission is applied as eight fills — four legs, opened and closed.
Read the result beyond the wings row alongside the wing widths row. On a symmetric butterfly the two tails are equal; if they are not, the structure is broken-winged and the lower of the two is the maximum loss.
Add an underlying price at expiry to value the butterfly at a particular finish, or leave it blank to skip that question entirely.

Limitations of the Butterfly Spread calculator

Every calculation makes assumptions. These are the ones that matter here.

Every figure is an at-expiry figure. Long butterfly options spend most of their life worth far less than their peak, because the peak requires the body's time value to have gone, so an unrealised result well below the maximum profit is normal rather than a sign of anything being wrong.
The maximum profit needs the underlying to finish exactly at the body strike. It is a single point on a payoff that slopes away in both directions, and treating it as an achievable target rather than as a boundary is the most common misreading of the structure.
Pin risk at the body is unusually acute. If the underlying settles at or near the body, the two short contracts may be partly assigned while the wings are exercised or abandoned separately, leaving an unhedged position that no at-expiry figure describes.
Assumes exactly the one-two-one ratio, with the body traded twice against one contract at each wing. Any other ratio is a different structure — a ladder or a ratio spread — and the payoff here does not describe it.
Assumes all four contracts share one underlying and one expiry, and that the whole structure filled at the net premium entered. Legging into four options across four bid-ask spreads rarely produces the price a combination order would.
American-style options can be assigned before expiry, and a butterfly has two short contracts to be assigned on. Resolving one leaves a position quite different from the one priced here until it is closed out.
Margin and buying power are excluded, and a short butterfly or one opened for a credit will carry a requirement the broker sets individually and can raise while the position is open.
Nothing here estimates the chance of finishing near the body, which is what the return on risk quietly depends on. A high ratio and a narrow profitable band are two descriptions of the same structure.

Frequently asked questions about Butterfly Spread

Why does one butterfly count as four option contracts?

Because the body strike is traded twice, against one contract at each wing. Commission attaches to those four fills, and to four more when the structure is closed. The cash figures still scale with contracts multiplied by shares per contract, never with the leg count — multiplying by four as well is the classic way to report a butterfly at four times its real size.

What is a broken-wing butterfly?

One whose wings are unequal — for example strikes at 50, 55 and 65, giving a 5-wide lower wing and a 10-wide upper one. The wings no longer cancel beyond the outer strikes, so the payoff settles away from zero on one side. That extra exposure is what the market pays for, and it is how such a structure can be opened for a credit.

Do calls and puts give the same butterfly?

With equal wings, yes — the payoff diagrams are identical, which is why the distinction is so easily missed. With unequal wings they are not. A call butterfly leaves its non-zero tail above the upper strike and a put butterfly leaves it below the lower one, so the same three strikes describe two different risk profiles.

Why does my butterfly show only one break-even?

Because the payoff does not cross zero on the other side. A broken-wing structure entered for a credit is often profitable across a whole side of the range, so there is no price there at which it is level. Rather than print a figure the payoff never reaches, the calculator reports none and the hint says which side of zero that segment stays on.

Why was my butterfly rejected as impossible?

Because those strikes and that premium produce a structure that either cannot lose or cannot win at any price, and neither is available in a traded market. Almost always it is a long butterfly entered for a credit, or a short one entered for a debit — check the premium selector and the long or short position field before the strikes.

Is the maximum profit realistic to expect?

It requires the underlying to finish exactly at the body strike at expiry, which is one price out of all of them. It is the top of the payoff rather than a likely outcome, and the return on risk that follows from it is a ratio between two extremes — a high figure generally goes with a narrow band of prices that produce any profit at all.

Can I use this as an iron butterfly calculator?

Not with its own legs, but its payoff is available here exactly. An iron butterfly sells a put and a call at the body and buys a wing either side, and at expiry that is the same shape as a long butterfly on the same three strikes. Enter it as a long butterfly with a debit equal to the wing width less the credit received, and the extremes and both break-evens match leg for leg.

Last reviewed 29 August 2026. See our methodology and editorial policy.

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