How-to guide

How to use the Founder Ownership & Dilution Calculator

Every round takes a slice. This shows how much you'll actually keep. Here's how to use it, with three examples.

Founders are routinely surprised by how little they own after a couple of rounds. This shows how SAFEs, option pools, and priced rounds dilute you — before you sign.

What this tool does

You enter your rounds, SAFEs, and pool; it shows founder ownership after each event, including the effects people forget (SAFE conversion, pool top-ups).

Who it's for

Founders modelling a raise who want to see the real ownership picture, not just the headline valuation.

How to use it — step by step

  1. Enter your starting cap table. Founders and existing holders.
  2. Add SAFEs and rounds. Amounts, caps, and valuations.
  3. Add the option pool. And whether it's pre- or post-money.
  4. Read ownership after each event. What you keep, step by step.

How to read your result

Two things surprise founders: SAFEs convert and dilute at the priced round (not when signed), and a pre-money option pool dilutes founders, not the new investor. Model both.

Worked examples

The same tool behaves differently depending on what you put in. Here are 3 situations.

A seed round

Inputs: One priced round.

What the tool shows: Shows the straightforward dilution from new money.

What to do: Know your post-round ownership before agreeing.

Stacked SAFEs

Inputs: Several SAFEs at different caps.

What the tool shows: Shows how they all convert at the priced round — often more dilution than expected.

What to do: Track total SAFE dilution, not each in isolation.

Pre-money option pool

Inputs: Investor asks for a pool in the pre-money.

What the tool shows: Shows the pool comes out of your slice, not theirs.

What to do: Negotiate pool size and timing deliberately.

Common questions

When do SAFEs dilute me? At the priced round when they convert — not when signed.

Who does the option pool dilute? In a pre-money pool, the founders — not the new investor.

Why model this early? So the ownership number doesn't shock you at closing.

A helpful estimate, not a guarantee. This tool works only off the numbers and assumptions you enter — it can't see your whole picture. Use it to get oriented and pressure-test your thinking, then sanity-check the big calls with an advisor. It isn't financial, tax, or legal advice.