Glossary
What Is Equity Dilution?
Updated · Team Fonda
Short answer
Equity dilution is the fall in your ownership percentage that happens when your company issues new shares, usually to investors, employees or a new co-founder. You keep the same number of shares, but they become a smaller slice of a larger total.
Key takeaways
- Ownership after a round = ownership before x (1 - percentage sold in the round).
- Dilution lowers your percentage, not your share count. Whether it lowers the value of your stake depends on the price of the new shares.
- Funding rounds, option pools, SAFEs and convertible notes all dilute you, and the effects stack.
- Model dilution before you agree to a round, not after.
What equity dilution means in plain words
A company is divided into shares. Your ownership is your shares divided by all shares that exist. When the company creates new shares and gives them to someone else, the total goes up and your fraction goes down. Nobody takes shares away from you. The pie is cut into more slices.
Dilution is the normal price of bringing in money or people. The question is never whether you get diluted. It is how much you give up and what the company gets in return.
How to calculate dilution
Formula
Ownership after = your shares / (existing shares + new shares). Shortcut: ownership after = ownership before x (1 - percentage sold to new holders).
In a funding round, the percentage sold is the investment divided by the post-money valuation. If the difference between pre-money and post-money is new to you, read pre-money vs post-money valuation first, because mixing them up changes the answer.
You can test different round sizes and valuations in the free equity dilution calculator.
A worked example
This is an illustration with made-up numbers. Say you and a co-founder each hold 4,000,000 shares, so the company has 8,000,000 shares and you each own 50%. An investor offers $500,000 at a $2,000,000 pre-money valuation.
| Step | Calculation | Result |
|---|---|---|
| Post-money valuation | $2,000,000 + $500,000 | $2,500,000 |
| Investor ownership | $500,000 / $2,500,000 | 20% |
| New shares issued | 8,000,000 x 20% / 80% | 2,000,000 |
| Your ownership after | 4,000,000 / 10,000,000 | 40% |
Example only. Real rounds often add an option pool, which dilutes founders further.
Your stake went from 50% to 40%. On paper its value did not fall: 50% of a $2,000,000 company and 40% of a $2,500,000 company are both $1,000,000. The company now also has cash to grow with.
What causes dilution
- Priced funding rounds. Investors buy newly created shares at pre-seed, seed and later rounds.
- SAFEs and convertible notes. A SAFE or convertible note does not dilute you on the day you sign it. It turns into shares at the next priced round, and the dilution arrives then.
- Employee option pools. Shares set aside for future hires count against existing holders, often the founders alone.
- New co-founders and advisers. Shares granted for work rather than cash dilute you in the same way.
Why it matters for a first-time founder
You first meet dilution when you split equity with a co-founder, and again each time you raise. Rounds compound. In the example above, a second round that sells 20% would take you from 40% to 32%, not to 20%. Small-looking percentages add up across several rounds, so it pays to keep a cap table, which is the list of who owns what, from day one.
Dilution is also a reason to prove your idea before you raise. Evidence such as paying customers supports a higher valuation, which means you sell less of the company for the same money. Fonda's journey follows the same order: the Validate phase comes well before the Raise step.
Common mistakes
- Signing several SAFEs without adding them up. Each one looks small. Together they can convert into a large share of the company.
- Ignoring the option pool. Ask whether the pool is created before or after the investment, because that decides who pays for it.
- Optimizing for percentage alone. A smaller share of a funded, growing company can be worth more than a large share of one that ran out of cash.
- Guessing instead of modeling. Put each scenario in a spreadsheet or calculator before you negotiate.
Frequently asked questions
Is equity dilution bad?
Not by itself. Dilution is how a company pays for cash and talent it cannot afford otherwise. It is a bad deal when the money raised does not increase the value of the company by more than the share you gave up.
Do I lose shares when I am diluted?
No. Your number of shares stays the same. The company issues new shares to someone else, so your shares represent a smaller percentage of the total.
Can founders avoid dilution?
Only by not issuing new shares, which means funding the business from revenue or savings. That approach is called bootstrapping. Founders who raise money can limit dilution by raising only what they need and by raising after they have evidence that supports a higher valuation.
What is anti-dilution protection?
It is a term some investors negotiate that adjusts their share price if the company later sells shares more cheaply. It protects the investor, not the founder, and its details vary. Ask a startup lawyer to explain any anti-dilution clause before you sign.