Know your numbers before you trade.

Stock position P/L & averaging down

See where your position stands, then see what adding more shares does to your average cost.

Add shares (averaging)

Averaging down lowers your break-even but also puts more money at risk in the same stock.

Options profit calculator

Long calls and long puts. See break-even, max loss and profit/loss at expiration, plus an estimate before expiration (Black-Scholes).

P/L at expiration

Estimated P/L by date (before expiration)

Rows are stock prices, columns are dates. Uses Black-Scholes with the IV above, so it is an estimate. Real prices change as IV changes.

Time decay (theta) visualizer

If the stock does not move, how much value does the option lose each day? Watch how decay speeds up near expiration.

This is why long-dated options decay slowly at first: most of the time value melts in the last 30–60 days.

Position size & risk

Decide how much you are willing to lose first. The calculator tells you how big the position can be.

Risk / reward

Entry, stop and target. See how much you could lose vs. gain, and how often a setup like this has to work just to break even.

Max profit / max loss

Pick a strategy. See the most it can make, the most it can lose, where it breaks even and the money it ties up. Per the number of contracts entered.

Margin calculator

How far margin stretches your cash, how much you borrow, the price that would trigger a margin call, and what the loan costs.

Short option margin estimate (uncovered)

Standard exchange formula for selling a naked option: the greater of 20% of the stock minus the out-of-the-money amount, or 10% of the stock (calls) or strike (puts), plus the premium.

Estimates use Reg T 50% initial and FINRA 25% minimum maintenance by default. Broker rules vary: many require 30–40% maintenance or more on volatile stocks, can raise requirements at any time, and can sell your shares without notice. Uses the stock price above.

Payoff diagram builder

Build up to 4 legs and see the profit/loss at expiration, the break-evens and the max profit and loss. Option quantity is contracts (×100); stock quantity is shares.

Break-even calculator

The price where a position stops losing money, including fees.

Implied volatility & Greeks

Type in an option's market price. The solver finds the implied volatility that Black-Scholes needs to match it, then shows the Greeks.

Delta: how much the option moves per $1 in the stock. Gamma: how much delta changes per $1. Theta: value lost per day from time passing. Vega: change per 1 point of IV. Model assumes no dividends and European-style exercise, so results are estimates.

IV crush calculator

Options often get cheaper right after earnings because implied volatility (IV) drops once the news is out. See what an option could be worth the day after the report for different stock moves.

Estimates use Black-Scholes, valued at the close of the first trading day after the report. Real prices also depend on bid/ask spreads and how far IV actually drops.