ESOP Pool Refresh Calculator
Size the new option-pool shares to top up to a target post-money percentage — and see the founder dilution it creates.
How it works
Post-money = pre + investment · Existing pool (post) = existing × pre ÷ post · New pool = target − existing pool (post)
Investors usually require the option pool to equal a target share of the post-money company, and the top-up is carved out of the pre-money — so founders, not investors, bear its dilution (the "option pool shuffle"). The existing pool shrinks as a share of the enlarged company after the round, and the new shares issued make up the difference to the target. Sizing the pool to real hiring needs, rather than a round-number percentage, directly protects founder ownership.
Worked example
On an $8M pre-money with a $2M raise, post-money is $10M and the investor takes 20%. An existing 2% pool dilutes to 2% × 8 ÷ 10 = 1.6% of the post-money company. To hit a 10% target pool you issue 10% − 1.6% = 8.4% of new option shares, and that 8.4% is founder dilution.
Frequently asked questions
Why does the pool dilute founders and not investors?
Because the pool is created in the pre-money — before the new money goes in — it comes out of existing holders’ ownership. Investors negotiate this deliberately so their post-money percentage is protected from future hiring grants.
What is a typical pool size?
Seed and Series A pools commonly land between 10% and 20% of post-money, sized to cover the option grants expected before the next round. Larger pools mean more founder dilution today, so bottom-up hiring plans beat round numbers.
How is this different from a normal dilution calc?
A plain dilution calculator only tracks equity sold to investors. This one isolates the option-pool top-up: how many new reserved shares you must create to reach a target, and the founder dilution that top-up causes.
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Educational estimate, not financial advice.