Cap Table Calculator

Think of a cap table like a pie that gets re-sliced every time someone new joins the table. When the company is founded, the founders own 100%. Each new investor, employee option grant, or advisor warrant adds more slices — and every existing slice shrinks proportionally. What the cap table calculator does is take the total number of all shares (the whole pie) and divide each stakeholder's count by that total to produce their ownership percentage.

The fully diluted share count is the key number. It includes not just shares already issued but also every share reserved in the employee option pool, even if no options have been granted yet. This is important because when a new investor evaluates your company, they calculate dilution against the fully diluted total — not the issued total. If your option pool has 1,000,000 reserved shares and you forget to include them, your ownership percentages will look artificially high until the investor runs their own numbers.

When a new funding round closes, fresh shares are created and issued to the new investor. Every existing shareholder — founders, previous investors, option pool holders — gets diluted by exactly the same proportion. A founder who held 70% before a round that issues 25% to new investors will hold roughly 52.5% afterward (70% multiplied by 75%). The calculator does this arithmetic instantly across all stakeholders, so you can see the post-round structure before agreeing to any term sheet.

Use this calculator when you are preparing for a funding conversation and need to know exactly what each stakeholder will own before and after the round. It is the right tool when you have actual share counts from your incorporation documents or existing cap table spreadsheet, and you want to stress-test a specific investment scenario quickly.

It is also useful when issuing new options to an employee and you want to communicate their ownership percentage accurately. Telling someone they are getting 50,000 options means nothing without context — showing them that 50,000 shares represents 0.5% of the fully diluted total makes the offer real and comparable to market benchmarks.

This calculator is not appropriate when your cap table includes convertible instruments with complex terms — tiered discounts, MFN provisions, or multiple conversion triggers — that change the share count depending on the scenario. In those cases a proper cap table management tool or a startup attorney's model is necessary. It is also not the right tool for waterfall analysis during an exit, which requires modeling liquidation preferences, participation rights, and seniority stacks that this calculator does not handle.

The most common mistake is entering only issued shares and forgetting the option pool. Founders frequently report a 70% ownership figure to investors that is based on issued-only shares, then discover mid-negotiation that their real fully diluted ownership is 58% once the pool is included. The consequence: the term sheet is renegotiated on worse terms because trust erodes when numbers do not match.

A second frequent error is treating the option pool expansion as neutral. Many Series A term sheets require the company to expand the option pool before close — meaning the new pool shares dilute the existing cap table, not the incoming investor. A 10% post-money option pool that requires a top-up from 5% to 10% can cost founders an extra 5 percentage points of ownership that they did not expect to lose.

The third mistake is confusing pre-money and post-money valuation when calculating ownership. If an investor says they are investing $2,000,000 at a $10,000,000 pre-money valuation, they expect 16.7% of the company post-money — not 20%. Calculating 20% (by dividing $2M by $10M) is the wrong math. The correct calculation is $2M divided by ($10M plus $2M), which gives 16.7%. This tool calculates ownership from share counts directly, bypassing this confusion entirely.

Ownership percentage for any stakeholder is simply their share count divided by the total fully diluted shares, multiplied by 100. If a founder holds 5,000,000 shares and the fully diluted total is 9,750,000, their ownership is 5,000,000 divided by 9,750,000, which equals 51.28%.

When a new round is added, the new total becomes the pre-round fully diluted count plus the new shares issued. The implied price per share is calculated by dividing the investment dollar amount by the number of new shares issued. If $1,500,000 buys 1,500,000 new shares, the price per share is $1.00. This price per share implies a post-money valuation equal to that price multiplied by the fully diluted post-round share count.

Post-money valuation is not calculated here because it depends on how your company values unexercised options — some companies use treasury stock method, others use the simple fully diluted count. The price per share output gives you the core number that feeds into any valuation conversation without requiring that judgment call from this calculator.

This calculator treats all shares as common-equivalent, which is standard for ownership percentage calculations but omits a critical real-world layer: preferred shares issued to investors almost always carry liquidation preferences that mean 20% economic ownership on paper may translate to 0% of proceeds in a modest exit. The ownership percentage you see here is the governance and upside number — it is accurate for voting control and for modeling high-value exits, but it overstates economic value in downside scenarios. Founders and employees with common shares should always model the waterfall separately before accepting an offer or signing a term sheet.