The short answer
Dilution is the decrease in an existing shareholder's ownership percentage when a company issues new shares, for example in a funding round, an option-pool top-up or a SAFE conversion. Your share count stays the same; your percentage falls.
- New shares reduce every existing holder's percentage.
- Dilution isn't bad by itself if the company's value grows more.
- Model rounds, option pools and SAFE conversions together.
- Price-based anti-dilution clauses are a different thing; see anti-dilution.
How it works
Ownership is your shares divided by total shares. When the company issues new shares, the denominator grows, so everyone's percentage drops unless they buy into the new round. The common sources are priced rounds, SAFE and note conversions, and new or larger option pools.
Worked example (hypothetical)
You own 6,000,000 of 10,000,000 shares: 60%. You raise $1.5M at a $6M pre-money valuation. Post-money is $7.5M, so investors get $1.5M ÷ $7.5M = 20%. The company issues 2,500,000 new shares (20% of the new 12,500,000 total). Your 6,000,000 shares are now 48%. You were diluted by 20% of your stake, but your 48% is of a company priced at $7.5M instead of $6M.
Why it matters to a pre-seed or seed founder
Early dilution compounds. Each round, pool expansion and SAFE conversion takes its share, and founders who stack several SAFEs without modeling them can be surprised at their first priced round. Decide how much you need, raise that, and model every instrument on your cap table before you sign. Our guide on how much to raise helps.
Frequently asked questions
Is dilution always bad?
No. Selling part of the company to fund growth is the point of raising. It's bad when you sell more than you need or at terms you didn't model.
Can investors avoid dilution?
Investors with pro rata rights can buy into later rounds to keep their percentage. Price-based anti-dilution clauses protect against down rounds, not ordinary dilution.
Does a SAFE dilute me?
Yes, when it converts. Post-money SAFEs make that ownership easy to calculate up front.