Fundraising Dilution Over Rounds Calculator
See how your ownership shrinks across seed, Series A and Series B as each round sells a slice of the company.
How it works
Ownership = start × (1 − d₁) × (1 − d₂) × (1 − d₃) · dilution multiplies, it does not add
Selling 20% in one round then 18% in the next does not remove 38% of your stake — each raise takes its slice of what is left, so the effects multiply. Your holding after each round is the previous holding times (1 − equity sold). That is why founders who look up after three rounds often own far less than the sum of the percentages they sold would suggest.
Worked example
A founder owning 100% who sells 20%, then 18%, then 15% keeps 100% × 0.80 × 0.82 × 0.85 = 55.8%. The three rounds sold 53 percentage points on paper, yet the founder’s stake fell by 44.2% — the gap is the compounding of dilution.
Frequently asked questions
Why isn’t total dilution just the rounds added up?
Each round dilutes the ownership that remains after the previous round, not the original 100%. So the percentages multiply rather than add, and the combined effect is always smaller than the raw sum of the slices sold.
Does an option pool count as a round here?
Yes — enter a pool top-up as one of the rounds, since carving out new option shares dilutes existing holders just like selling equity to investors. For the option-pool mechanics specifically, use the ESOP pool refresh calculator.
How can founders limit dilution?
Raise less at higher valuations, hit milestones between rounds to lift the price, and keep option-pool top-ups sized to actual hiring needs. Pro-rata rights let early investors defend their stake but do not help founders.
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Educational estimate, not financial advice.