Employee Stock Options (ESOPs), Explained

Stock options are how startups pay people in upside they cannot afford in cash. They are also one of the most misunderstood parts of a startup offer — by the founders granting them and the employees receiving them. A candidate hears "0.5% of the company" and either dismisses it as Monopoly money or fantasizes about a life-changing payout, and both reactions are usually wrong.

The truth sits in the mechanics: the pool the equity comes from, the strike price you lock in, the vesting that earns it, and the exercise decision that turns it into real shares. Understand those four things and you can value an option grant honestly — whether you are writing the offer or reading it.

This guide explains how option pools work, what a strike price and vesting actually mean for the holder, the exercise trap that catches people who leave, and how to think about what equity is really worth.

The option pool: where the equity comes from

When a startup grants equity to employees, it comes out of a dedicated option pool — typically 10 to 20% of the company set aside for the team, advisors, and future hires. Crucially, when the pool is created or expanded, the dilution lands on the founders and existing investors, not on the people receiving the options. That is the point: it is the mechanism by which a company shares ownership with the people building it.

Investors usually insist on a healthy pool at a financing, because they want the company to be able to attract talent without going back for more equity every time. For founders, the pool is the budget you grant from; for employees, it is the proof that the company actually intends to share the upside.

Strike price and why timing matters

Every option grant comes with a strike price — the fixed price at which you can later buy your shares, set at the share's fair market value on the day of the grant. The whole value of an option is the gap that opens up between that locked-in strike price and what the shares are actually worth later.

This is why joining early can be worth more than the raw percentage suggests: an early employee locks in a low strike price, so if the company grows, more of the increase is theirs. A later hire with the same percentage but a much higher strike price captures less of the same growth. It is also why equity and cash trade off the way they do — a topic we cover in depth in salary versus equity in startup compensation.

90 days

Vesting and the exercise trap

Options do not arrive all at once. They vest on a schedule — almost always the same four-year, one-year-cliff structure used for founders, which we break down in startup vesting and cliffs explained. You earn the right to your options gradually as you stay and contribute.

But vesting only gets you the right to buy. To turn vested options into actual shares you must exercise them — pay the strike price out of your own pocket. And here is the trap that catches people: when you leave a company, you typically have a short window, often 90 days, to exercise your vested options or lose them. Exercising can cost real cash and trigger a tax bill, so an employee who leaves may face a hard choice: pay to keep equity in a company whose outcome is uncertain, or walk away from options they spent years earning.

What an option grant is actually worth

The honest answer most founders won't say out loud: often nothing. Most startups fail, and options only pay out if the company is eventually sold or goes public at a value above your strike price. That does not make them worthless — it makes them a high-variance bet whose expected value depends on several things at once:

• The percentage you actually own (ask for it as a percentage, not just a share count).
• The company's odds and trajectory — a tiny slice of a likely winner can beat a big slice of a long shot.
• Your strike price — lower is better, and earlier usually means lower.
• The terms — vesting, the post-departure exercise window, and any acceleration.

For an employee, the practical rule is to treat options as a bonus on top of a salary you can comfortably live on, never as guaranteed pay. For a founder, the rule is to be transparent: explain the percentage, the strike, and the risks honestly, because an offer the candidate doesn't understand builds neither trust nor retention.

Granting and receiving options well

1. Founders: size the pool deliberately

   Set a pool large enough to hire the team you need for the next stage, knowing it dilutes you and your investors — not your hires. Top it up at financings rather than over-granting early.

2. Founders: be transparent in offers

   State the percentage, the strike price, the vesting, and the exercise window plainly. Candidates who understand the deal value it more and resent it less.

3. Employees: translate the offer

   Convert any grant into a percentage of the company and ask about the strike price, the current valuation, and the post-departure exercise window before you weigh it.

4. Everyone: get the equity split right first

   Options sit on top of the founder cap table. If the underlying equity split between co-founders is broken, no option plan fixes it.

Stock options are a genuinely powerful way for startups to share the wealth they hope to create — but only when both sides understand the mechanics. Granted thoughtfully and explained honestly, they align a team around the same outcome. Treated as magic numbers on an offer letter, they breed confusion and resentment. Learn the four levers — pool, strike, vesting, exercise — and you can read or write an equity offer for what it really is. When you are ready to build the team you will be granting this equity to, start by finding the right people on Foundersbase.