Round Lot Jump to the manual 100 shares = 1 lot

Instrument · arithmetic only, no data feed

Options payoff calculator: break-even, maximum gain and maximum loss

Enter a strike and a premium, choose one of the four positions, and the arithmetic is done in front of you: where the position breaks even, what it can gain, what it can lose, and the shape that falls out of those three.

Written under the standing byline J. Marchetti options and execution

Share price at expiry: long call, strike 50, premium 3

404550556065
Break-even is 53, not 50. The strike is where the right starts being worth something; the premium still has to be earned back before the position is level, and the distance between those two marks is exactly what the contract cost.
Break-even
53.00share price at expiry
Maximum gain
unlimitedper contract
Maximum loss
300.00per contract
Capital at risk
300.00premium paid

This calculator needs JavaScript. The arithmetic it performs is stated in full below: break-even is the strike plus the premium for a call and the strike minus the premium for a put, and every figure is multiplied by 100 shares per contract.

All figures are the theoretical outcome at expiry, before commissions, fees, taxes and dividends, and they assume the position is held to expiry rather than closed early. No market data is used or fetched.

A draftsman's brass French curve and a fine steel nib pen on a sheet of ruled plate paper, a single bent line of shadow crossing beneath them
A French curve and a nib pen. Every payoff drawn here is two straight arms and one bend — the bend sits at the strike, and the arithmetic decides where the line crosses zero.

The arithmetic, written out

A bought option starts at minus the premium and stays there until the strike, because below it the right is worth nothing and the premium is already spent. Past the strike, intrinsic value climbs one-for-one with the share price. Break-even is therefore the strike plus the premium for a call, and the strike minus the premium for a put.

The written side is the same line reflected through zero. The writer keeps the premium as the maximum gain and begins losing past the same break-even point. For a written call that loss has no upper bound, because a share price has none; for a written put it stops at zero, which makes the worst case the strike minus the premium, multiplied by 100.

Reading the four positions against each other

Switching the position selector while leaving the strike and premium alone is the fastest way to see that the four positions are two contracts seen from both ends. A long call and a written call produce the same line reflected through zero: what one gains the other loses, at every price, with the premium moving in the opposite direction. The same holds for the put pair.

That symmetry is also where the asymmetry of risk becomes visible. The bought positions cap the loss at the premium and leave the gain open on the call side. The written positions do the reverse, and on a written call the calculator reports the maximum loss as unlimited because the contract genuinely places no ceiling on it. Seeing those two facts on the same axes, one after the other, is more instructive than any description of them.

What the calculator deliberately leaves out

It models the contract at expiry and nothing else. No commissions, no regulatory fees, no taxes, no dividends, and no early assignment — all of which are real and none of which are contract arithmetic. It also does not price the option: it takes the premium as an input rather than estimating what one should cost, because that would require a volatility assumption and the point of this tool is that every number in it can be checked by hand.

For the same reason there is no market data anywhere in it. Nothing is fetched, nothing is stored, and the page works identically offline. If you want the mechanism behind the shape rather than the numbers, the introduction walks through it, and the greeks page covers why the line is curved before expiry and straight at it.

FAQ

Questions about the payoff calculator

Where does break-even come from?

For a call it is the strike plus the premium; for a put, the strike minus the premium. The buyer has already paid the premium, so the position must recover that amount before it is level. The calculator applies the same rule to the written side, where the writer keeps the premium until the price passes that point.

Are these per-share or per-contract figures?

Per share, matching how premiums are quoted. One listed US equity contract covers 100 shares, so multiply every output by 100 for the contract. The calculator shows both, because the factor-of-100 slip is the single most common arithmetic error with options.

Why is the maximum loss on a written call shown as unlimited?

Because nothing caps how far a share price can rise, and an uncovered call obliges delivery at the strike regardless. That is not a modeling choice; it is the contract. Covering the position with shares or a second contract is what turns that into a number.

Does this account for commissions, fees or dividends?

No. It computes the contract arithmetic only, so the numbers are the theoretical outcome at expiry before any cost. Real results also move with early assignment, corporate actions and taxes, none of which are modelled here.