Long Put Calculator
Buying a put buys the right to sell 100 shares at the strike. This calculator shows what that costs, where it breaks even, and what it pays at every stock price at expiration. Free, no signup.
What is A Long Put?
A Long Put is a bought put option: you pay a premium for the right to sell 100 shares at the strike price. It gains value as the stock falls below the strike and expires worthless if the stock finishes at or above it. The most you can lose is the premium.
This calculator returns the breakeven, max loss, the payoff at every price, and — if you supply days to expiry — delta, theta and vega.
Your Put
Leave implied volatility blank and it is backed out of the premium you typed, so the Greeks reflect your own inputs rather than an assumed vol. Days to expiry only affects the Greeks — the payoff table and chart are always at expiration.
Hedging shares you already own? Use the protective put calculator. Want to cut the cost by selling a lower put against it? See the debit spread calculator.
Your Payoff
P&L at Expiration by Stock Price
| Stock at Expiry | Put Value | P&L | Return on Premium |
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How to Use the Long Put Calculator
Enter four things and the payoff is fully determined: the stock price now, the strike of the put you are buying, the premium per share you are paying, and how many contracts. Premium is entered the way it is quoted — a put shown at 2.00 costs $200 for one contract, and the calculator applies the 100x multiplier for you. Days to expiry and implied volatility are optional and change only the Greeks; the table and the chart always show P&L at expiration, where the put is worth its intrinsic value and nothing else.
The table is the part worth studying. It prices the position at a spread of stock prices around the strike so you can see how much of the move you actually need. A put that is 5% out of the money and costs 2% of spot does not start paying until the stock is 7% lower — that gap between "the stock fell" and "the trade made money" is where most long puts are lost.
The Formulas
Breakeven
Strike − Premium
Max Loss
Premium × 100 × Contracts
P&L at expiry, stock at P
(max(K − P, 0) − Premium) × 100 × Contracts
Max Profit — only if the stock goes to $0
(Strike − Premium) × 100 × Contracts
Worked Example
The stock is at $100. You buy one 95 put for $2.00. Breakeven is $95 − $2.00 = $93.00. Max loss is $2.00 × 100 = $200, which is what you lose on any close at or above $95. If the stock closes at $90, the put is worth $5.00 intrinsic, so P&L is ($5.00 − $2.00) × 100 = +$300. The arithmetic maximum, ($95 − $2.00) × 100 = $9,300, requires the stock to be worth nothing at expiration.
On max profit: the large theoretical maximum exists only because a stock can in principle go to zero. It is a boundary of the payoff function, not a forecast — judge the put by what it pays at prices the stock can realistically reach.
Insurance Versus a Directional Bet
The same contract does two very different jobs depending on whether you hold the stock. The payoff maths is identical; what changes is the standard you judge it against.
As insurance
Held against shares you own, the put is a floor. Below the strike your stock keeps falling but the put rises one-for-one against it, so the combined position stops losing. You expect the premium to be a cost, most of the time, in the same way a household insurance premium is a cost.
The right question is not "will this put profit?" but "is the floor worth the annualised drag?" A put costing 2% of spot for three months is roughly an 8% annual drag if you keep rolling it — weigh that against how much downside you are unwilling to sit through.
As a directional bet
Held on its own, the put is a bearish position with a deadline. You need direction, size and timing all to work: the stock has to fall, fall past the breakeven, and do it before expiration. Being right about the direction and late about the timing pays nothing.
Theta is against you every day, and it accelerates into the last few weeks. Shorting the stock has no deadline but unlimited risk; the put caps the loss at the premium and charges you time decay for the privilege. Both trades are defensible — just be clear which one you are placing.
The IV crush risk when you buy puts into a spike
Puts get expensive exactly when people want them. Implied volatility rises into earnings, Fed meetings and selloffs, and the premium you pay rises with it. A long put is long vega, so if IV falls after you buy, the option loses value even with the stock unchanged — and that vega loss can swamp the delta gain from a moderate fall. This is the single most common way a "correct" put trade still loses money.
Two checks before paying up. IV rank: if implied volatility is high against its own history, you are buying at peak pricing and the move has to be larger than usual to compensate. And the implied move: the chain already prices in an expected move, and the put only wins if the stock exceeds it. Buying after a market has already fallen 5% in a week is often the worst of both — some of the move is behind you and the premium still reflects the panic.
If the premium looks steep and you still want the exposure, selling a further out-of-the-money put against yours turns it into a put debit spread: cheaper, less vega-sensitive, capped upside. The debit spread calculator prices that trade-off directly.
Frequently Asked Questions
How do you calculate the breakeven on a long put?
Breakeven = strike − premium per share. A 95 put bought at $2.00 breaks even at $93.00. Between $93 and $95 the put has intrinsic value but not enough to cover what you paid, so the position is still down.
What is the maximum loss on a long put?
The premium, and nothing more: premium × 100 × contracts. One 95 put at $2.00 risks $200. You lose the full amount on any close at or above the strike, because the put then expires worthless.
What is the maximum profit on a long put?
(Strike − premium) × 100 × contracts, reached only if the stock goes to zero. For the 95 put at $2.00 that is $9,300 per contract — an arithmetic boundary, not a base case. Use the payoff table for outcomes the stock can plausibly reach.
Why did my put lose money when the stock fell?
Usually implied volatility. Buy a put while IV is elevated — into earnings or a panic spike — and the premium is inflated. When IV normalises, the vega loss can outweigh the delta gain from a modest fall, with theta subtracting value every day on top. Check IV rank before paying up.
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