Stock Option Value Calculator

Value a stock option grant at different exit outcomes, after strike price, dilution and tax. The result updates as you type so you can compare scenarios quickly.

The method

How it is worked out

Value = (exit ÷ diluted shares − strike) × options × (1 − tax)
fully diluted
All shares, options and convertibles counted as if exercised

Keep in mind

What it leaves out

  • PreferencesInvestors are paid first; in a low exit common may get less than this.
  • Exercise windowLeaving usually means exercising within 90 days, cash up front.

Use the calculator to compare scenarios rather than as a guaranteed forecast.

About the Stock Option Value Calculator

Value a stock option offer at realistic exit outcomes after dilution, strike price and tax, and compare it with salary you are giving up.

How it works and an example to tryShow less

How to use the result

Your ownership is options over fully diluted shares, reduced by expected dilution. Exit value per share is the exit divided by the diluted share count; gain is the excess over strike times options, then taxed.

Example to try

20,000 options at £1.20 on 12m fully diluted shares, 30% more dilution and a £150m exit are worth about £113,000 after tax, against £50,000 of salary forgone over five years.

Put it to work

Try it on a real situation

Load an example

What moves the result most

    Worked out from your figures above. Tap a row to try it.

    Who uses it, and when

    Candidates weighing a startup offer and employees deciding whether to exercise.

    Mistakes worth avoiding

    • Valuing options at the last round price as if they were cash.
    • Ignoring the preference stack that pays investors first.
    • Missing the 90-day exercise window on leaving.

    Questions

    What does the Stock Option Value Calculator do?

    Value a stock option grant at different exit outcomes, after strike price, dilution and tax.

    How should I use the result?

    Your ownership is options over fully diluted shares, reduced by expected dilution. Exit value per share is the exit divided by the diluted share count; gain is the excess over strike times options, then taxed.

    Does TechBullion store the information I enter?

    The core calculation or transformation runs in your browser. Normal website security and analytics may still record page-level events, but the tool does not need to create a public record from your inputs.

    What mistakes do people make with a stock option value calculator?

    Valuing options at the last round price as if they were cash. Ignoring the preference stack that pays investors first. Missing the 90-day exercise window on leaving.

    Is the result guaranteed?

    No. Use the result as a practical check or planning aid and verify important decisions with the relevant primary source, provider or professional advice.

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    Results are estimates based on the figures entered, for general information only, and not financial, investment, tax or legal advice. See our terms of use.