Stock Option Calculator

Employee stock options give you the right to buy company shares at a fixed strike price. Intrinsic value (spread) = max(0, current fair market value − strike price). Paper value = number of vested or total options × spread. Options are "in the money" when FMV exceeds strike; out of the money when strike is above FMV.

Paper value is not cash — you must exercise (buy shares) and later sell or hold to realize gains. Exercise triggers tax events for ISOs and NSOs differently. Private company FMV comes from 409A valuations and may change each year. This calculator does not model vesting, AMT, or liquidity timing.

Example: 10,000 options, $1.50 strike, $8.00 FMV. Spread = $6.50/share. Paper value = $65,000. Exercising costs $15,000 (10,000 × $1.50) plus taxes. If FMV doubles to $16, spread = $14.50 and paper value = $145,000 — but you still need cash to exercise.

409A valuations set FMV for private companies, usually updated after funding rounds or every 12 months. A fresh round at a higher price often increases FMV and your paper value even if you cannot sell shares yet.

Out-of-the-money options have zero intrinsic value today but may still have time value if far from expiration. Private company options often have 10-year terms — FMV can cross strike years after grant.

Exercise cost is separate from tax. To own the shares you pay strike × number of options. NSO exercises create ordinary income on the spread. ISO exercises may trigger alternative minimum tax without immediate regular income if you hold shares.

Worked example after partial vest: 10,000 total options, 6,000 vested, $2 strike, $10 FMV. Spread $8 × 6,000 vested = $48,000 paper value on vested portion. Exercising all vested shares costs $12,000 cash plus tax — liquidity events (IPO, tender offer) determine when you can sell.

Secondary markets and tender offers sometimes let employees sell a fraction of vested shares before IPO. Paper value can exceed what you can actually monetize if no buyer exists.

This is planning math only — not tax, legal, or investment advice. Consult a CPA before exercising large option grants.

Post-termination exercise windows vary: 90 days is common for NSOs; some companies extend to 7–10 years for founders or offer 10-year windows after IPO. Missing the window forfeits vested options.

Liquidity preferences on preferred stock can mean employees with common options see little in a modest acquisition even when headline sale price looks positive — waterfall analysis is separate from spread math.

Track vested vs unvested separately in your spreadsheet. Job decisions at month 11 vs month 13 can differ by tens of thousands of dollars when a cliff is near.

Net exercise (cashless exercise) lets you exercise without upfront cash by withholding shares — tax withholding still applies and reduces shares received.

Black-Scholes and 409A valuations differ — employees see 409A FMV for exercise; option grant accounting for the company uses different models internally.

Tender offers may cap how many shares employees can sell — paper value on all vested options can exceed what a tender accepts, leaving remaining value illiquid until IPO or next event.

Company stock splits adjust option counts and strike prices in tandem — paper value math stays consistent after split but grant paperwork must reflect corporate action records.

Spread at grant (FMV minus strike on grant date) determines ISO $100K annual exercisability limits — large grants may split into ISO and NSO buckets automatically under IRS rules.

Company acquisition may cash out options at deal price minus strike — paper value before close can differ from payout if unvested options are cancelled or accelerated per deal terms.

Grant paperwork lists vesting and expiration separately from spread math — confirm post-termination exercise deadlines in your plan administrator portal.