Startup Dilution Calculator

Who owns what. Without the legal fees.

Dilution is the drop in your ownership when a company issues new shares: your ownership percent equals your shares divided by the total shares after the round. Your share count does not change, but the total grows, so your slice shrinks. Own 100% before a €250,000 round at a €1,000,000 pre-money valuation and you hold 80% after, because the new shares expand the total.

How it's calculated

Two steps, both pure share counting:

  • Total shares = sum of every holder's shares
  • Ownership % = your shares / total shares x 100

A priced round issues new shares at the round price (pre-money valuation / existing shares). Those shares raise the total, so every existing holder's percent falls. For a solo founder who starts at 100%, ownership after the round is pre-money / (pre-money + raise) x 100.

Worked examples

Raise Pre-money Founder % after
€250,000 €1,000,000 80.0%
€1,000,000 €3,000,000 75.0%
€2,000,000 €4,000,000 66.7%

How it works

Add shareholders to the list, one row each.

Pick a role (Founder, Investor, Employee, or Pool) and type the number of shares.

The ownership bars and total update as you type. Use the × at the end of a row to remove a shareholder.


Why it matters

Equity is the most expensive currency you have. Giving it away without understanding the dilution impact is a common founder mistake.

This tool gives you a quick snapshot of your cap table so you can negotiate with clarity.

Ownership Structure

Total shares 0

Questions people ask

What is startup dilution?

Dilution is the drop in your ownership percentage when a company issues new shares, usually to raise a funding round or to fill an option pool. Your share count stays the same, but the total share count grows, so your slice of the whole gets smaller. Owning 100% of 10 million shares means 100%; after a round mints 2.5 million new shares, those same 10 million are 80%.

How much equity do founders give up in a seed round?

A typical seed round trades 10% to 25% of the company for the raise. The exact number is the raise divided by the post-money valuation. Raise 1,000,000 at a 4,000,000 pre-money (5,000,000 post-money) and investors take 20%, leaving founders and the pool to split the remaining 80%.

Does the option pool dilute founders or investors?

It depends on when it is created. A pool set up before the round (a pre-money pool, the usual investor ask) comes out of the founders' shares. A pool topped up after the round dilutes everyone on the cap table in proportion to what they already hold. Model both and the difference in founder ownership is often several points.