Stock market calculators
The sums behind a share offering, a buyback, a concentrated portfolio, an earnings gap or a losing streak, each printed line by line so you can check the arithmetic and see which input moves the answer most.
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Stock Trading
Share Dilution CalculatorYour ownership percentage and earnings per share after a company issues new shares, and the dilution in each.
Background: fully diluted shares
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Investing
Buyback EPS CalculatorEarnings per share after a buyback shrinks the share count, net of any new shares issued at the same time.
Background: whether buybacks help holders
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Investing
Position Concentration CalculatorThe weight of each holding and sector in your portfolio, and what a fall in the largest one does to the total.
Background: how big one stock should be
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Earnings
Earnings Gap Loss CalculatorWhat an overnight gap of 5%, 10% or 20% does to a position, in dollars and as a share of your account.
Background: the earnings gap
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Investing
Volatility Drag EstimatorWhy equal gains and losses leave you behind, and the compound return a run of ups and downs really produces.
Background: why smooth returns compound faster
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Dividends
Dividend Cut CalculatorAnnual income before and after a dividend cut, the new yield on cost, and the capital needed to replace the lost income.
Background: dividend coverage
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Stock Trading
Average Down CalculatorYour new average cost after buying more shares lower, with fees, and the price the stock must reach to break even.
Background: what averaging down really does
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Prop Trading
Losing Streak CalculatorWhat a run of losing trades does to an account at different risk levels, and how long a streak a drawdown limit survives.
Background: sizing for a losing streak
Before you trust an output
Every calculator runs in your browser and sends nothing anywhere. An answer is only as good as the inputs, and the inputs that matter most are the ones you have to look up or estimate: the share count in the latest filing, the size of a gap the options market is pricing, the risk you really take per trade. A calculator will turn a guess into a number with two decimal places without complaint.
Change one input at a time and watch the output. When a small change in the offering price or the gap size moves the result a long way, that sensitivity is the useful finding, because it tells you which number deserves the most checking.