Dilution is the reduction in an existing shareholder's percentage ownership when a company issues new shares. Every time a startup raises money, creates an employee option pool or converts SAFEs and notes into equity, founders and early shareholders own a smaller slice of the company. Dilution isn't necessarily bad: a smaller slice of a much more valuable company can be worth far more. But founders who don't understand it can end up with less ownership and control than they expected. This guide explains how dilution works, with worked examples, typical numbers per round and ways to manage it.
Dilution is the fall in existing shareholders' ownership percentage when a startup issues new shares through funding rounds, option pools, SAFEs, notes or warrants. Typical dilution is 10% to 25% per round at seed and Series A and less later. Founders often own 10% to 30% at IPO, and dilution is worthwhile when the capital raised grows the company's value faster than ownership falls.
How dilution works
Ownership is your shares divided by the total number of shares outstanding. When a company issues new shares to investors, your share count stays the same but the total rises, so your percentage falls.
Example: two founders own 5 million shares each, 10 million in total, so each owns 50%. An investor agrees to invest US$2 million at an US$8 million pre-money valuation. The post-money valuation is US$10 million, so the investor should own 20%. To achieve this, the company issues 2.5 million new shares (2.5 / 12.5 = 20%). Each founder still holds 5 million shares but now owns 40% (5 / 12.5). The price per share is US$0.80, so each founder's stake is worth US$4 million on paper, compared with nothing that could be sold before.
Our guide to post-money valuation calculation explains pre-money and post-money in more detail.
The sources of dilution
- Priced equity rounds: Seed, Series A, B and later rounds issue preferred shares to investors.
- Employee option pools: shares reserved for current and future employees; investors often require the pool to be created or expanded before their investment, so existing shareholders bear the dilution.
- SAFEs and convertible notes: these convert into shares at the next priced round, often at a discount or valuation cap, adding dilution that founders sometimes underestimate. See SAFE versus convertible note.
- Warrants and venture debt: lenders often receive warrants to buy shares; see venture debt explained.
- Acquisitions paid in stock: issuing shares to buy another company dilutes existing holders.
- Down rounds with anti-dilution protection: can shift extra dilution onto founders and common shareholders.
Typical dilution per round
Dilution varies widely, but common ranges in recent years have been:
| Stage | Typical dilution from new investors | Notes |
|---|---|---|
| Pre-seed | 5% to 15% | Often via SAFEs |
| Seed | 10% to 25% | Plus option pool creation |
| Series A | 15% to 25% | Option pool often topped up |
| Series B | 10% to 20% | Larger rounds, higher valuations |
| Series C and later | 5% to 15% | Can be lower for fast-growing companies |
The hottest AI companies have sometimes raised very large rounds with relatively little dilution because their valuations rose so quickly, while companies that struggle may give up more. Our guides to how much equity to give seed investors and pre-seed versus seed funding go deeper into early rounds.
Dilution over a startup's life: an example
Consider two founders who start with 100% between them and raise the following rounds:
- Pre-seed (SAFEs): 10% dilution. Founders now own 90%.
- Seed: 20% to investors plus a 10% option pool. Founders own about 63%.
- Series A: 20% to investors plus a 5% pool top-up. Founders own about 47%.
- Series B: 15%. Founders own about 40%.
- Series C: 10%. Founders own about 36%.
After five rounds, the founders together own roughly a third of the company. If the company is then worth US$2 billion, their combined stake is worth about US$720 million, far more than 100% of a company that never raised money and stayed small. Many successful founders own between 10% and 30% of their companies at IPO.
Option pools and the "option pool shuffle"
Investors usually want a pool of unissued options large enough to hire key employees over the next 12 to 24 months. If the term sheet requires the pool to be created before the investment, as part of the pre-money valuation, the dilution falls entirely on existing shareholders, effectively lowering the price investors pay. Founders can negotiate the size of the pool based on a realistic hiring plan rather than accepting an oversized one. Our guide to the employee option pool covers this in detail.
Down rounds and anti-dilution protection
A down round happens when a company raises money at a lower price per share than in a previous round. Besides the normal dilution from new shares, down rounds can trigger anti-dilution provisions that protect earlier preferred investors by adjusting the price at which their preferred shares convert into common shares.
- Broad-based weighted average: the most common and founder-friendly form; it adjusts the conversion price partially, taking into account how many new shares are issued at the lower price.
- Full ratchet: resets the earlier investors' conversion price to the new, lower price, which can cause severe dilution for founders and employees; it's rare in modern venture deals.
Companies that raised at peak 2021 valuations and later reset, such as Rapyd, illustrate how down rounds redistribute ownership. Our guides to down rounds and liquidation preferences explain how these terms interact.
Dilution versus liquidation preferences
Ownership percentages tell only part of the story. Preferred shareholders usually have liquidation preferences, the right to get their money back before common shareholders in a sale. If a company sells for less than the total invested, or below the price of later rounds, founders and employees can receive much less than their ownership percentage suggests. Miro, valued at US$17.5 billion in 2022 and agreeing to a sale at about US$1.8 billion in equity value in 2026, shows how preference stacks can determine who recovers value in a sale below the last round.
How founders can manage dilution
- Raise what you need: raising more than necessary means giving up more ownership; raising too little risks running out of money, so plan for 18 to 24 months of runway.
- Grow before raising: higher traction supports higher valuations and less dilution.
- Negotiate the option pool: size it to a real hiring plan.
- Model SAFEs and notes: calculate how they convert before signing more of them.
- Consider non-dilutive funding: grants, revenue-based financing and venture debt can fund growth without new equity; see non-dilutive funding for startups.
- Use pro rata rights strategically: founders can't usually buy into rounds, but understanding investors' pro rata rights helps predict future cap tables.
- Track your cap table: keep a fully diluted cap table up to date; see how to read a cap table.
Fully diluted ownership
When discussing ownership, investors and founders usually mean "fully diluted" ownership: the percentage you'd own if all options, warrants, SAFEs and convertible notes were converted into shares. Fully diluted figures give a more realistic view than counting only issued shares. Term sheets typically specify that valuations and ownership percentages are calculated on a fully diluted basis, including the post-money option pool.
Dilution for employees
Employees with stock options are diluted in the same way as founders. A grant representing 0.5% of the company at Series A might represent 0.3% after later rounds. That's normal, and the value of the grant can still rise if the company's valuation grows faster than dilution. Employees should ask for the number of shares outstanding on a fully diluted basis, the latest preferred share price and the 409A value to understand what their options are worth.
A quick dilution formula
To estimate your ownership after a round, multiply your current percentage by one minus the percentage sold in the round (including any option pool increase that comes out of the pre-money). For example, if you own 40% and the company sells 20% to new investors while adding a 5% pool from the pre-money, your new ownership is roughly 40% × (1 − 0.25) = 30%. Repeating this for each planned round gives a simple projection of how your stake might evolve. A spreadsheet cap table model, updated with real terms as you raise, gives more precise results, particularly once SAFEs and notes with different caps are involved.
Secondary sales don't dilute
When existing shareholders sell shares to new investors in a secondary sale or tender offer, no new shares are created, so other shareholders aren't diluted. Ownership simply moves from seller to buyer. Our guide to tender offers explains how these transactions work.
Frequently asked questions
What is dilution in a startup?
Dilution is the reduction in existing shareholders' percentage ownership when a company issues new shares, for example to investors in a funding round or to an employee option pool.
How much dilution is normal in a funding round?
Typical ranges are 10% to 25% at seed and Series A, and lower in later rounds, though it varies widely by company and market conditions.
Is dilution bad for founders?
Not necessarily. If the money raised helps the company grow its value faster than ownership falls, founders' stakes become worth more despite owning a smaller percentage.
How do SAFEs cause dilution?
SAFEs convert into shares at the next priced round, usually at a valuation cap or discount, which adds dilution on top of the new round itself.
What is anti-dilution protection?
It's a clause that adjusts earlier preferred investors' conversion price if the company later raises at a lower price, shifting some dilution to founders and common shareholders.