Macroplane › Free Tools › Startup Stock Option Calculator

Startup Stock Option Calculator

See what your employee stock options could be worth at an exit — accounting for your strike price, dilution from future funding rounds, and a growing company valuation. Your share count stays fixed while each round shrinks your ownership; a rising valuation usually more than makes up for it.

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Frequently asked questions

How do I calculate what my startup stock options are worth?

Your options are worth your ownership percentage of the company's equity value at exit, minus the cost to exercise (options × strike price). Ownership shrinks as the company raises money and issues new shares, but a rising valuation usually more than offsets that dilution.

How does dilution from funding rounds affect my equity?

Each funding round issues new shares, so your fixed number of options becomes a smaller slice of a bigger pie. A 20% round dilutes you by roughly 20%. Over several rounds the effect compounds, but if the valuation grows faster than you're diluted, your stake still gains value.

What is a strike price and exercise cost?

The strike (or exercise) price is what you pay per share to convert each option into stock. Your total exercise cost is options times strike. Your gain is the value of the shares at exit minus that cost — and if the exit price per share is below your strike, the options are underwater and worthless.

Does this account for taxes and liquidation preferences?

No — it's a pre-tax estimate of gross value. Real outcomes are affected by income/AMT taxes when you exercise, capital-gains tax at sale, and investor liquidation preferences that get paid before common shareholders. Treat the result as an upper-bound sketch, not a guarantee.