Option Pool Impact Calculator
See who pays for a new option pool: how a pre-money pool carve-out splits ownership between founders and the incoming investor.
How it works
Post-money = pre-money + investment · Investor % = investment ÷ post-money × 100 · Existing shareholders % = 100 − investor % − pool % · (pool carved from pre-money)
Investors usually require an option pool to be created before their money goes in — the "pre-money pool shuffle". Because the pool is carved out of the pre-money valuation, its entire dilution lands on existing shareholders, not the new investor. That quietly lowers the effective pre-money price founders receive, so a 10% pool can cost founders several points of ownership beyond the round itself.
Worked example
Raising $2,000,000 at an $8,000,000 pre-money ($10,000,000 post) gives the investor 20%. Adding a 10% pre-money option pool leaves existing shareholders 100% − 20% − 10% = 70% — 10 points below the 80% they would keep with no pool.
Frequently asked questions
Why does the option pool dilute founders more than investors?
When the pool is created pre-money, it is funded entirely out of the existing shareholders’ stake. The investor buys their percentage of the post-money company after the pool already exists, so their slice is untouched by it.
Can the pool come out of the post-money instead?
Yes, if negotiated. A post-money pool is shared proportionally between founders and the new investor, which is far more favorable to founders. Term sheets usually default to a pre-money pool, so it is worth negotiating.
How big should an option pool be?
Enough to cover planned hires until the next round — commonly 10–20% of the fully diluted cap table. Sizing it to an actual hiring plan avoids over-diluting for options that never get granted.
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Educational estimate, not financial, tax or investment advice.