Box Spread Calculator
A bull call spread and a bear put spread on the same strikes. A financing trade.
The stock
Everything else is measured against this price.
Enter a ticker to pull the live stock price automatically.
Filled from the live quote when you enter a ticker. You can still edit it.
Where you think the stock will be. Adds a marker to the chart.
Today, unless you are modelling a past or future entry.
The contracts
Premiums are per share, the way they are quoted. One contract covers 100 shares.
Long call (lower)You pay
Calculated by a modelModel estimate, not a quote
45 days
100 shares of exposure
Leave blank and it is solved from the premium you entered.
Short call (upper)You receive
Calculated by a modelModel estimate, not a quote
45 days
100 shares of exposure
Leave blank and it is solved from the premium you entered.
Long put (upper)You pay
Calculated by a modelModel estimate, not a quote
45 days
100 shares of exposure
Leave blank and it is solved from the premium you entered.
Short put (lower)You receive
Calculated by a modelModel estimate, not a quote
45 days
100 shares of exposure
Leave blank and it is solved from the premium you entered.
Rates, dividends and costs4.00% rate · 0.00% yield
Roughly the Treasury yield matching your expiration.
Annual, continuous. Raises put values and lowers call values.
Charged per leg, both to open and to close.
Per contract. Usually a few cents.
Per share, applied against you on entry.
Profit and loss
The solid line is the exact payoff at expiration. Move the sliders to see the position before then.
Hover, tap or use arrow keys to read the curve
- At expiration
- Today (model estimate)
- Current price
| Stock price | Profit or loss |
|---|---|
| 82.75 | +$2.40 |
| 84.19 | +$2.40 |
| 85.63 | +$2.40 |
| 87.06 | +$2.40 |
| 88.50 | +$2.40 |
| 89.94 | +$2.40 |
| 91.38 | +$2.40 |
| 92.81 | +$2.40 |
| 94.25 | +$2.40 |
| 95.40 | +$2.40 |
| 96.84 | +$2.40 |
| 98.28 | +$2.40 |
| 99.71 | +$2.40 |
| 101.15 | +$2.40 |
| 102.59 | +$2.40 |
| 104.03 | +$2.40 |
| 105.18 | +$2.40 |
| 106.61 | +$2.40 |
| 108.05 | +$2.40 |
| 109.49 | +$2.40 |
| 110.93 | +$2.40 |
| 112.36 | +$2.40 |
| 113.80 | +$2.40 |
| 115.24 | +$2.40 |
| 116.68 | +$2.40 |
Drag towards expiration to watch time value drain out of the position.
Shifts every leg's implied volatility. Changes the Greeks and every date before expiration.
Result
Measured at Sep 19, 2026 · 45 days to expiration
$0.00
The worst case at expiration, including fees.
$2.40
The best case at expiration, including fees.
$997.60
Paid out of your account when the position is opened.
None
This position never crosses zero at expiration.
$997.60
A debit position is fully paid for at entry, so the cost is the requirement.
$2.60
To open. Closing costs are not included.
+$2.40
If the stock finished expiration exactly where it is now.
Not set
Enter one to see the profit at a specific price.
Probability
Model estimates, not forecasts. The assumptions behind each number are stated in full.
100.0%
Assumes a lognormal terminal price (geometric brownian motion), the same distribution black-scholes assumes with volatility of 30.0% and risk-neutral drift. Real returns have fatter tails than this model assumes, and volatility itself changes. Other tools quote different numbers mainly because they assume a different volatility or a different expected drift.
Greeks
How the position responds to price, time, volatility and rates, for the whole position rather than a single contract.
- delta
- −0.00
- share equivalents
- How many shares this position behaves like. A delta of 50 gains roughly $50 for every $1 the stock rises.
- gamma
- 0.0000
- delta per $1 move
- How quickly delta changes. High gamma means the position gets directional fast as the stock moves.
- theta
- 0.11
- dollars per day
- What time decay costs or earns each calendar day, if nothing else changes.
- vega
- 0.00
- dollars per 1% of volatility
- What a one percentage point change in implied volatility is worth to this position.
- rho
- −1.23
- dollars per 1% of rates
- What a one percentage point change in interest rates is worth. Usually the smallest of the five.
These inputs produce a profit at every possible stock price, which real markets do not offer.
Check that each leg is on the correct side (buy or sell) and that the premiums are per share rather than per contract.
Profit table
Every combination of price and date, so you can see the position from any angle at once.
| Stock price | Aug 5, 2026estimate | Aug 13, 2026estimate | Aug 20, 2026estimate | Aug 28, 2026estimate | Sep 4, 2026estimate | Sep 12, 2026estimate | ExpirationSep 19, 2026 |
|---|---|---|---|---|---|---|---|
| 125.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 122.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 120.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 117.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 115.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 112.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 110.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 107.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 105.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 102.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 100.00now | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 97.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 95.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 92.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 90.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 87.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 85.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 82.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 80.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 77.50 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
| 75.00 | −$2.52 | −$1.65 | −$0.88 | −$0.01 | +$0.76 | +$1.63 | +$2.40 |
Every column before expiration is a model estimate that assumes implied volatility stays where it is today. Only the expiration column is arithmetic rather than a forecast.
Notes on the box spread
- The payoff at expiration is the strike width, regardless of the stock price.
- On American-style options a box is not risk-free: early assignment can break it apart. Boxes have caused catastrophic retail losses for exactly this reason.
- Four legs means four spreads to cross, which frequently costs more than the rate advantage is worth.
- Max loss
- $0.00
- Max profit
- $2.40
- Breakeven
- —
How a box spread works
Four legs that between them guarantee the distance between the two strikes at expiration, whatever the stock does. The payoff is a fixed number, so what you are really trading is the interest rate implied by paying for it now and collecting it later.
When traders use it
As a way to borrow or lend at the rate the options market implies, rather than as a directional trade. It is included here mostly so the flat payoff can be seen.