Free tool
ESOP vesting calculator
How many options are vested on any date, and every tranche still to come. Monthly, quarterly, half-yearly, annual or single-date, with or without a cliff.
The link carries your figures in the address itself, so share it only with people you would show the grant to. Nothing is stored on our side either way.
The full schedule
Every vesting event from the start date to the end of the term, with the cumulative total after each one. Rows on or before your chosen date are marked as vested.
| Date | Month | Vesting | Cumulative | Status |
|---|---|---|---|---|
| The schedule appears here once your figures are in. | ||||
How the schedule is worked out
Every step, in the open, so you can check a grant letter against it rather than take either on trust. A calculator you cannot check is an ad.
Months, not days, and what that fixes
Elapsed time is counted in whole months from the vesting start, not in days. A month is complete when the same day-of-month arrives again, and where that day does not exist it clamps to the last day of the shorter month: a grant starting 31 January completes its first month on 28 February, or 29 February in a leap year. Because the arithmetic is month-based rather than day-based, leap years change nothing about how much has vested.
The cliff, then the rounding
Before the cliff, nothing is vested. At the cliff, the whole elapsed share vests at once: the cliff months divided by the total months, multiplied by the grant. After the cliff, vesting continues on the frequency you chose, on the same day-of-month as the start date, and the final event completes the grant exactly. Cumulative totals are rounded down to whole options at every step, so each tranche is the difference between two rounded cumulative figures and the last tranche absorbs any remainder. That is why an individual tranche can differ by one option from its neighbours.
The edge cases, shown rather than smoothed
If the cliff is longer than the total vesting period, the tool shows the literal result, which is that the entire grant vests in one step at the cliff, and it says so as a warning rather than silently adjusting your input. A date before the vesting start shows zero. A grant of zero, a term of zero and a negative cliff are refused with a message instead of a number.
What this tool does not know
It puts no value on your options, models no tax at grant, exercise or sale, and applies no plan rules. Vesting can be paused, accelerated, cancelled or forfeited by terms that live in your plan document and your grant letter, and those documents are the authority over anything shown here.
For the concepts in plain words, read how ESOP vesting works and the guide to startup equity and ESOPs. For how grants and vesting are recorded so each employee can see their own position, see the Compensation and Equity module.
Questions with complete answers
What does this calculator not know?
Your plan document. Plans differ on rounding, on whether vesting pauses during unpaid leave, on what happens to unvested options when someone leaves, on acceleration in a sale, and on how long a leaver has to exercise. None of that is modelled here, because none of it can be inferred from a grant size and a date. The tool does the schedule arithmetic; your plan rules decide everything around it.
Why does it never show what my options are worth?
Because nobody can honestly tell you. An option is the right to buy a share at a fixed strike price, and what it turns out to be worth depends on a future share price that does not exist yet. Any figure a calculator put on your screen would be a guess dressed as a number. This tool counts units, tells you when they vest, and leaves valuation to your company and your own advisers.
Does this work outside the country my company is in?
Yes. Vesting is contract mechanics, not local law: a four-year schedule with a one-year cliff counts the same in Berlin, Lagos, Jakarta, Singapore, London and San Francisco. What does differ by country is the tax treatment of grant, exercise and sale, and this tool says nothing about tax anywhere. Choose your own date and number format above so the output reads the way you write dates and group digits.
What happens if the cliff is longer than the vesting term?
The tool shows what the arithmetic actually implies, which is that nothing vests until the cliff and then the entire grant vests in one step, and it warns you that this is unusual. It does not quietly correct your input. If that is not what your plan intends, the plan or the numbers you were given need fixing, and it is better to see that here than to discover it at the cliff.
Is anything I type here saved or sent anywhere?
No. The whole calculation runs in your browser and nothing leaves the page. There is no email wall, no account and no storage, so closing the tab clears it. The one exception is the link button, which puts your figures into the address itself so you can send them to someone; the page tells you that before you copy, and it is your choice whether to use it.
A schedule an employee can read for themselves beats one they have to ask you for.