What is equity dilution?
Equity dilution happens when a company issues new shares — usually to raise money or reward employees — which reduces the ownership percentage of everyone who already holds shares. Each existing slice of the pie stays the same size, but the pie itself gets bigger.
Formula:
new ownership % = shares held ÷ new total shares × 100Dilution is not inherently bad. Taking investor money in exchange for a smaller percentage of a much more valuable company is the whole point of venture financing. The real question is how much ownership is given up per dollar raised — and whether the new capital grows the company's value fast enough to more than offset the smaller slice.
A founder owning 100% of a $2M company and a founder owning 10% of a $200M company hold the same dollar amount of equity. The second founder is massively better off, because execution after each round justified the dilution many times over. This calculator lets anyone — founder, investor, employee with stock options, or curious reader — model how a specific round reshapes ownership.
How to use this calculator
- Pick a perspective. Use the selector at the top of the Quick tab: Round overview (neutral company-side view), New investor's check (sizing a new investment), or Existing shareholder (modeling dilution on an existing stake).
- Enter the pre-money valuation. The value everyone agrees the company is worth before new money comes in.
- Enter the investment amount. The total cash new investors are adding in this round.
- Add the option pool top-up if applicable. If investors require the employee-stock pool to be expanded pre-money, existing shareholders absorb that dilution.
- Read the updated ownership percentages. Results update instantly as you type.
- Switch to Advanced cap table for per-stakeholder output, or Multi-round waterfall to model cumulative dilution across several rounds.
Equity dilution examples
Example 1 — Simple seed round, no option pool
You raise $500,000 at a $2,000,000 pre-money valuation. No option pool top-up is required.
| Input | Value |
|---|---|
| Pre-money valuation | $2,000,000 |
| Investment | $500,000 |
| Post-money valuation | $2,500,000 |
| Investor ownership | 20.0% |
| Founder ownership after | 80.0% |
Example 2 — Same round, with 10% option pool shuffle
Same round as above, but investors require a 10% post-money option pool created pre-investment. Founders absorb the pool creation.
| Input | Value |
|---|---|
| Pre-money valuation | $2,000,000 |
| Investment | $500,000 |
| Target option pool | 10% (post-money) |
| Investor ownership | 20.0% |
| Option pool | 10.0% |
| Founder ownership after | 70.0% |
The 10% option pool came entirely out of the founders' share, not the investors'. That is the option pool shuffle in action.
Example 3 — SAFE converting at priced round
A $200,000 post-money SAFE at a $3,000,000 cap converts at a $5,000,000 pre-money Series A round of $2,000,000.
| Item | Value |
|---|---|
| SAFE amount | $200,000 |
| Valuation cap | $3,000,000 |
| Effective SAFE ownership (post-money SAFE) | ~6.67% |
| Series A investor ownership | ~28.6% |
| Option pool (if 10% top-up) | 10.0% |
| Founder ownership after Series A | ~54.7% |
Because the SAFE's cap ($3M) was below the Series A pre-money ($5M), the SAFE holder gets a better price per share than the Series A investors — more shares for the same $200k.
Key dilution terms explained
- Pre-money valuation
- The company's agreed value before new investor money is added. Used to set price per share.
- Post-money valuation
- Pre-money plus the new investment.
post-money = pre-money + investment. - Fully diluted shares
- The total share count if all options, warrants, SAFEs, and convertible notes were exercised or converted today. Used for all meaningful ownership math.
- Option pool / ESOP
- Shares reserved for future employee equity grants. Investors typically require a 10–15% pool before investing.
- Option pool shuffle
- Creating or expanding the option pool pre-investment, so that founders alone bear the dilution rather than splitting it with new investors.
- SAFE (Simple Agreement for Future Equity)
- A Y Combinator instrument that converts to equity at a future priced round, typically with a valuation cap and/or discount.
- Pre-money SAFE vs post-money SAFE
- Pre-money SAFEs dilute one another when multiple convert together. Post-money SAFEs lock in a fixed percentage of the post-money cap table, pushing that dilution onto founders.
- Convertible note
- Short-term debt that converts to equity at a qualified financing. Like SAFEs, has a cap and discount, but also accrues interest and has a maturity date.
- Anti-dilution provision
- A term that protects investors from dilution in a down round by adjusting their conversion price downward — either full-ratchet or (more commonly) weighted-average.
- Down round
- A funding round priced at a lower valuation than the previous round. Triggers anti-dilution adjustments and hits common shareholders (founders, employees) the hardest.
- Pro-rata rights
- The right for an existing investor to buy enough shares in future rounds to maintain their current ownership percentage.
- Cap table
- The authoritative spreadsheet listing every shareholder, their share count, share class, and ownership percentage — both basic and fully diluted.
What's a normal dilution percentage?
Typical founder dilution per round, based on 2024–2025 U.S. venture market data:
| Round | Typical range | Median (2025) |
|---|---|---|
| Pre-Seed | 5–15% | ~10% |
| Seed | 15–25% | ~19% |
| Series A | 15–25% | ~20% |
| Series B | 10–20% | ~15% |
Founders completing three or more rounds typically exit with a combined 15–30% of the company. Factors that push dilution above these ranges: low valuations, large option pool top-ups, SAFEs with low caps stacked before the priced round, and down rounds.
Frequently asked questions
How do I calculate equity dilution?
Equity dilution = new shares issued ÷ (existing shares + new shares). Your new ownership % = your shares ÷ new total shares × 100. If the option pool is expanded pre-money, founders absorb that dilution in addition to the investor's share.
What is the option pool shuffle?
The option pool shuffle is when investors require the option pool to be created or expanded before their investment closes. The pool comes out of the pre-money valuation, meaning founders bear the dilution rather than splitting it with the new investors. It's one of the most commonly misunderstood terms in seed financings.
How much equity should I give investors at seed?
Typical seed-round dilution is 15–25%, with a 2025 median around 19%. Add 10% if investors require a new option pool, bringing total founder dilution to roughly 25–30% at seed. If you're asked for more than 30% at seed (excluding option pool), push back or shop the round.
Do SAFEs dilute founders immediately?
SAFEs don't dilute on the cap table the day you sign them — they convert to equity at the next priced round. But their conversion shares are calculated at signing via the valuation cap, and at a priced round those shares may dilute more than expected if the round's pre-money is significantly above the cap.
What is a post-money SAFE?
The Y Combinator post-money SAFE (2018 version) locks in a fixed percentage of the post-money cap table at the valuation cap. The investor's percentage is protected from dilution by other SAFEs converting in the same round — founders bear that dilution instead. It's simpler to model than pre-money SAFEs but typically more dilutive to founders.
How does anti-dilution protection work?
Anti-dilution protection adjusts the conversion price of preferred shares downward in a down round. Full-ratchet anti-dilution resets the investor's price to the new round's price (aggressive, rare). Weighted-average (narrow or broad-based) adjusts price based on the size of the new round — far more common.
Is 20% dilution too much for a seed round?
No. 20% is within the typical seed-round range of 15–25% and near the 2025 median of 19%. Once you include a 10% option pool top-up, combined founder dilution often reaches 28–30% at seed — still normal.
How do I avoid excessive dilution?
Raise less by being capital-efficient, negotiate higher valuations on the back of real traction, keep option pool requests reasonable (push for a pool top-up post-investment), and avoid stacking many low-cap SAFEs before a large priced round.
What happens to my equity in a down round?
New investors buy shares at a lower price than previous rounds. Common holders (founders, employees) are heavily diluted. Preferred holders with anti-dilution protection have their conversion ratios adjusted, which further dilutes common. Down rounds also often reset vesting, refresh option pools, and include pay-to-play provisions that wipe out non-participating investors.
How does a convertible note affect my cap table?
Convertible notes don't appear on the cap table until they convert at a qualified financing, usually with a valuation cap and a discount (20% is typical). At conversion they issue preferred shares and dilute all existing holders — including founders and any SAFEs converting at the same round.
What is the difference between pre-money and post-money valuation?
Pre-money is the company value before new investor money. Post-money = pre-money + investment. Investors own (investment ÷ post-money) of the company. Always confirm which valuation you're being quoted — a $10M valuation with a $2M raise is very different depending on which definition applies.
How many rounds of funding before founders are diluted below 50%?
Founders typically cross the 50% threshold between Seed and Series A. After Series B, combined founder ownership is commonly 30–45%. After Series C and later, founders often own 15–25% combined. Use the multi-round waterfall above to see your specific trajectory.