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Option Pool Dilution Calculator

Estimate dilution from creating a new employee option pool.

6 min guideTransparent methodologyGo to calculator ↓
01 / UNDERSTAND THE CONCEPT

Reserved equity has an ownership cost.

An option pool reserves shares for employees and other eligible service providers. On a fully diluted basis, a newly created pool reduces existing holders’ ownership even before the options are granted or exercised.

The timing of a pool increase matters. A pre-money pool top-up in a financing can fall primarily on existing shareholders. This tool isolates pool creation so that its effect is clear, without combining it with financing terms.

02 / THE MATHEMATICS

The formula, made clear.

Retained ownership = current ownership × (1 − new pool percentage)
New pool target
Total newly reserved options as a percentage after the pool is created.
Fully diluted
Assumes all reserved options are included in the share total.
03 / A WORKED EXAMPLE

Put the numbers in context.

Creating a 10% pool reduces an 80% holder to 72%. Other existing holders retain 18%, and the new pool represents 10%.

Illustrative scenario
InputExample value
Your current ownership80%
New pool target10%
Your ownership after pool creation72%
MODEL BOUNDARIES

What this calculation assumes

An entirely new pool with no existing reserve, created independently of a financing. Not a pre-money pool top-up model; ungranted, granted and outstanding options need separate treatment in a real cap table.

FROM UNDERSTANDING TO ACTION

What to consider next.

For a financing, establish whether the pool target is measured before or after the round and who bears the increase.

How we approach financial models →
THE OAKSHORE NETWORK

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