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Stock Option Value Calculator

Value vested stock options as the spread between share price and strike, after tax.

About Stock Option Value Calculator

Options are worth the spread, not the share price, and only the vested portion is available. The exercise cost is real cash you must find up front, which is why a large paper gain can still be hard to realise. Employees consistently overestimate option value by using the share price rather than the spread, and by ignoring both the exercise cost and the tax charge on exercise.

Formula

Stock Option Value

Net value = vested options × (share price − strike) × (1 − tax rate)

spread
Gain per share on exercise
exercise cost
Cash needed to buy the shares

Worked example

With the default values below, Stock Option Value Calculator returns Net Value After Tax of $26,000.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Options heldminimum 0
20,000
Strike priceminimum 0
1
Current or expected share priceminimum 0
5
Share of the grant vestedaccepts 0–100 %
50 %
Tax rate on the gainaccepts 0–100 %
35 %

Results

Net Value After Tax
$26,000.00
Gross Spread on Vested Options
$40,000.00
Cost to Exercise Vested Options
$10,000.00
Tax on the Gain
$14,000.00
Vested Options
10,000

Step by step

  1. 1Values used
  2. 2Stock Option Value
  3. 3Net Value After Tax= 26,000.00
  4. 4Gross Spread on Vested Options= 40,000.00
  5. 5Cost to Exercise Vested Options= 10,000.00
  6. 6Tax on the Gain= 14,000.00
  7. 7Vested Options= 10,000

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Stock Option Value calculated?

Net value = vested options × (share price − strike) × (1 − tax rate) Options are worth the spread, not the share price, and only the vested portion is available. The exercise cost is real cash you must find up front, which is why a large paper gain can still be hard to realise.

Why does Stock Option Value matter?

Employees consistently overestimate option value by using the share price rather than the spread, and by ignoring both the exercise cost and the tax charge on exercise.

What values do I need to enter?

This calculator takes 5 inputs: Options held, Strike price, Current or expected share price, Share of the grant vested, Tax rate on the gain. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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