Cap table and dilution calculator

How it works

A cap table shows who owns what, and what each holder would receive if the company were sold. This tool works through a SAFE or note, one or more priced rounds with an option pool top-up, and an exit. It shows the price per share of each round, how the SAFEs and notes convert, each holder's fully diluted ownership after every round, and the exit waterfall with liquidation preferences. It is arithmetic on your own terms and gives no investment, legal or tax advice.

1. Price a round with the option pool created before the money. The pre-money valuation is divided by every share counted before the new money: the existing shares, the shares the SAFEs and notes convert into, and the new option pool top-up. The pool is therefore created before the investment (the option pool shuffle), so it dilutes the existing holders and not the new investor. The top-up is sized so that the whole pool is the target share of the post-money fully diluted shares.price = pre-money / (existing shares + conversion shares + pool top-up); new investor shares = investment / price; pool top-up = (T x (V + I) / V x (existing + conversion shares) − existing pool) / (1 − T x (V + I) / V), with T the target pool share, V the pre-money and I the investment
2. Convert SAFEs and notes at the better of cap or discount. Each SAFE or note converts at the lowest of its cap price, its discount price and the round price, which gives the holder the most shares. A post-money cap is divided by the company capitalisation including all the conversion shares, so a post-money SAFE always buys the share of the company equal to its amount over its cap before the new money. A pre-money cap is divided by the shares that exist before the conversion. A note converts its principal plus simple interest. Because the cap price, the round price and the pool top-up depend on each other, the tool solves them together by repeating the calculation until it settles.cap price = cap / (existing shares + conversion shares) for a post-money cap, or cap / existing shares for a pre-money cap; discount price = round price x (1 − discount); conversion price = lowest of the three; shares = (amount x (1 + rate x years)) / conversion price
3. Track fully diluted ownership. After each round every holder's share is their shares over all shares, option pool included. The converted SAFEs, the pool top-up and the new investors each appear as their own holder, so you can see who is diluted by what.ownership = holder shares / total fully diluted shares; effective pre-money = price x shares before the round
4. Pay out an exit by seniority. From the exit value, take off debt and fees. Preferred series that keep their preference are paid in order of seniority (equal ranks share pro rata), each up to its preference. A non-participating series takes the better of its preference and converting to common, so series with the lowest preference per share convert first. A participating series takes its preference and then shares the rest as if converted, and a capped one stops when its total reaches the cap or converts if that pays more. What is left is shared by the common shares and the option pool in the money.preference = money paid in x preference multiple; a non-participating series converts when its share of the residual per share exceeds preference / shares; a capped series converts when residual per share exceeds cap x money paid in / shares

Sources

The methods and default figures rest on these public sources. The wording here is our own; read the source for its full text.

• The SAFE: The standard way startups raise money (post-money safe and user guide) (opens in a new tab), Y Combinator, Post-money safe introduced 2018; page read October 2026. Post-money valuation cap, what the company capitalisation includes (all SAFE money, existing options and the pool, but not a new or increased pool in the priced round), conversion at the cap price or the discounted price, and an example of about 15% sold for $1M on a $6.7M post-money cap. The user guide PDF could not be read as text, so details are taken from the page.
• Negotiating the Option Pool (opens in a new tab), Cooley GO (Cooley LLP), Last reviewed 2 March 2023. The pool as a share of the post-closing fully diluted capitalisation, counted in the pre-money so existing holders carry the dilution.
• Venture Deals: Be Smarter Than Your Lawyer and Venture Capitalist, Fourth Edition, Brad Feld and Jason Mendelson; John Wiley and Sons, 2019. Liquidation preferences, participation, conversion and the option pool in term sheets. Bibliographic details (fourth edition, 2019, ISBN 9781119594826) confirmed from library and retailer records; the book itself was not read for this tool.
• Modelling Liquidation Preferences in Cap Tables (opens in a new tab), Allied VC, Undated web page, read October 2026. A worked example of non-participating and participating preferences at a $10M exit with a $3M preference and a 30% stake, which the tool's unit test reproduces. The page cites a Carta example; Carta's own publication was not read.