Bear Put Spread Calculator

A bear put spread buys a put (a right to sell) at a higher strike, the agreed exercise price, and sells a lower-strike put on the same stock or index with matching expiry and quantity. Net debit is the premium paid minus premium received. That debit is the maximum expiry loss per unit; breakeven is the bought strike minus the debit. Multiply per-unit amounts by total units for position totals. Charges are excluded. The Probability of Profit label only compares current price with breakeven; it is not a measured chance.

Put debit spread or put credit spread?

This page calculates a bearish put debit spread. Debit means money paid to open the position. A put credit spread reverses the bought and sold strikes and receives money upfront; its usual name is a bull put spread. Entering that arrangement here does not turn this tool into a credit-spread calculator.

If you meant a bearish credit spread, read the bear call spread explanation. Calls and puts create different obligations. A similar market view does not make their input directions interchangeable.

Enter premiums per unit and quantity separately

• Current Price: the underlying stock or index level used for distance from breakeven. It is not a live option quote or an expiry-date selection.
• Buy Put Strike (Higher) and Sell Put Strike (Lower): the agreed exercise prices of the purchased and written puts. Check the same underlying and expiry yourself because the form has no controls for them.
• Buy Put Premium and Sell Put Premium: prices per underlying unit, not the total cash amount of each leg. A leg means one of the option positions in the spread.
• Lot Size: underlying units in the contract you are examining. Confirm the quantity for that contract with the exchange or broker rather than relying on the preset.
• Number of Lots: matching contract counts on both sides. Total underlying units equal Lot Size multiplied by Number of Lots.

Use a higher bought strike, a lower sold strike and a positive debit smaller than the strike gap. The tool does not reliably reject reversed strikes or unsuitable premiums. Blank or zero entries can substitute hidden defaults, so clear and re-enter every field before comparing results.

Read the expiry bounds in the right units

A price at or below the lower strike reaches maximum spread profit at expiry. A price at or above the higher strike loses the opening debit. Between the strikes, each further fall increases the gross payoff until the lower strike is reached. Breakeven itself produces no gross profit or loss. The money cards round to whole rupees, including per-unit debit and breakeven, so fractional premiums can make the displayed figures differ from the exact arithmetic.

Worked example with an assumed contract quantity

This is a made-up example, not a current exchange contract or market quote. Assume Current Price 1,000, Buy Put Strike 1,000, Buy Put Premium ₹70, Sell Put Strike 900, Sell Put Premium ₹30, Lot Size 20 and Number of Lots 2. Both puts refer to the same underlying and expiry.

• Total quantity: 20 × 2 = 40 units.
• Net Debit: ₹70 − ₹30 = ₹40 per unit. Total Debit and Max Loss: ₹40 × 40 = ₹1,600.
• Strike gap: 1,000 − 900 = 100. Max Profit: (100 − 40) × 40 = ₹2,400.
• Breakeven: 1,000 − 40 = 960. The displayed reward per risk is 2,400 ÷ 1,600 = 1.5.
• Maximum return on debit: 2,400 ÷ 1,600 × 100 = 150%. Distance from the assumed current price: (1,000 − 960) ÷ 1,000 × 100 = 4%.

At an illustrative expiry price of 980, the purchased put has ₹20 of exercise value per unit and the sold put has none. Spread profit is (20 − 40) × 40 = −₹800. At 960, exercise value equals the debit, so the gross result is ₹0. At 900 or lower, the spread reaches its ₹2,400 profit cap. These are expiry scenarios, not a forecast or prices available for an early exit.

Why the probability card cannot price your risk

The calculator has no time-to-expiry or implied-volatility input. Implied volatility means the movement reflected in option prices. Its probability wording changes solely with the position of current price relative to breakeven. That comparison cannot establish the likelihood of a profitable expiry. The fixed Outlook text also says nothing about current market conditions.

The maximum-return percentage has a different meaning: it describes a maximum possible expiry payoff compared with the debit. A large ratio does not establish that outcome is likely. Use the risk and reward calculator to examine a separate planned loss and gain without treating either as a probability.

Three strike widths compared (made-up premiums)

The strike gap is the distance between the two put strikes. A wider gap raises both the debit and the profit cap. The table below uses made-up premiums, a bought strike of 1,000 and a quantity of 20 units (one lot of an imaginary contract). Real premiums depend on the market, so treat these as practice numbers only.

The narrowest spread has the smallest debit but also the lowest cap. The widest spread has the largest possible profit, but it needs a bigger fall to get there and risks a bigger debit. Before comparing real spreads, check that the sold put is not so cheap that you are paying almost the full cost of a single put.

Costs and exits can change the cash result

No brokerage, statutory charges or bid-ask spread is deducted here. The bid-ask spread is the gap between available buying and selling prices. Use actual executable premiums when comparing a proposed spread; the last traded prices of its legs may not be available together.

Expiry arithmetic also differs from closing the spread beforehand. An early exit requires prices for both options, which can change with time and volatility. The options payoff tool can help examine other expiry structures, but a payoff boundary does not certify settlement funding or broker margin. Check the requirements of the actual contracts separately.

Bear put spread versus buying a single put

A single long put costs its full premium and keeps gaining as the price keeps falling. A bear put spread costs less because the sold put gives back some premium, but the gain stops at the lower strike. In the 1,000 / 900 example above, a single 1,000 put at a premium of 70 would have a breakeven of 930, while the spread breaks even at 960.

• Cost: the spread debit (40 in the example) is lower than the single put premium (70).
• Breakeven: the spread breaks even sooner, at 960 against 930.
• Upside: the spread profit is capped at 60 per unit. The single put has no cap other than the underlying reaching zero.
• Time: both lose value as expiry approaches if the price does not move, but the sold put offsets part of that loss in the spread.

Which one fits depends on how far you expect a fall to go and how much you want to risk. This page only does the arithmetic. It does not tell you which is better.

Closing or adjusting before expiry

Many traders close before expiry. Closing the spread means selling the put you bought and buying back the put you sold. The cash result is the closing price of the bought put minus the closing price of the sold put, minus what you paid to open. This calculator does not take closing prices, so work it out by hand with the actual premiums you can trade.

• Close both legs together: this avoids ending up with only one put, which has a very different risk.
• Rolling: closing the spread and opening a new one at different strikes or a later expiry. Each step has its own debit and costs.
• Leg risk: if you close one leg first, you hold the other alone until the second order is filled.

Common mistakes when using this calculator

• Typing the total cost of a leg instead of the premium per unit.
• Swapping the strikes so that the bought strike is lower than the sold strike. That is a different structure.
• Mixing expiries between the two puts. A spread across two dates is a calendar or diagonal spread, which this tool does not cover.
• Leaving a field blank and trusting a hidden default.
• Forgetting brokerage, STT (securities transaction tax) and other charges, which cut into a small profit cap.
• Reading the probability card as a prediction.

After a trade, write down your planned exit and the result in your journal so you can compare plan and outcome later. For related checks see the credit spread calculator, the breakeven points calculator, the bull call spread calculator and the risk reward ratio page.

Bear put spread questions

Sources

• OIC: bear put construction and expiry boundaries, checked 16 Oct 2026.
• Fidelity: debit, breakeven and cost treatment, checked 16 Oct 2026.