Dilution is the most quoted and least understood number in startup finance. Every founder can repeat the rule of thumb — expect to end up with ten to twenty percent at exit. Almost none can show the math that gets them there, or, more importantly, the two or three decisions that move the number by ten points.
This piece walks a realistic path from incorporation to Series C. The numbers are illustrative; the shape of the math is not.
Starting point: two founders, no investors
Two co-founders incorporate. They split equity sixty-forty after a short negotiation and set up a standard four-year vesting schedule on each of their grants. The initial cap table is simple: one hundred percent of the shares live with the two of them, on a four-year vest.
The first dilution event has already happened, and neither founder noticed it: the vesting itself. If either of them leaves in year one, unvested shares return to the company and effectively dilute the other founder's ownership on a fully-diluted basis. This is not usually catastrophic, but it is the first reminder that ownership on paper and ownership in practice are different objects.
The pre-seed pool: the free ten percent
Before any outside money arrives, the founders create an option pool. Ten percent is typical. The mechanics matter: pool creation dilutes only the founders, because nobody else is on the cap table yet.
Founders now own ninety percent fully diluted. The pool holds ten percent, unallocated. This is the cheapest dilution the company will ever pay, and the pool the founders will ever have the most control over.
Seed: SAFEs, notes and the first real cut
The company raises one million dollars on SAFEs at a five million dollar post-money cap, then another five hundred thousand on a second tranche at seven million. Two more hires happen, using two percent of the pool.
At this stage the fully-diluted math depends on assumptions about when the SAFEs convert. If we assume a priced round clears at exactly the cap, the seed investors take about twenty-one percent between them. Founders are now around seventy percent, the pool at eight percent (six unallocated, two granted).
The lever that mattered here: the SAFE caps. The difference between raising at a five and a seven post-money cap is about six percent of ownership, permanently. Founders who raise on 'friendly' caps to close faster pay for it forever.
Series A: the pool refresh that founders forget
The company raises eight million dollars at a thirty-two million post-money. The lead requests the option pool be topped up to twelve percent post, out of the pre-money.
This is where the math gets subtle. The eight million of new money buys twenty-five percent post-money. But the pool top-up is sized out of the pre-money, meaning the existing shareholders — founders, seed investors, pool — dilute to make room for both the new investor and the new pool. Founders end up at around forty-five percent, seed investors at fifteen, pool at twelve, lead at twenty-five, other new investors at three.
The lever that mattered here: the size of the pool refresh. Every extra point in the pool costs founders roughly point six of a point of ownership, because it comes out of the pre-money not the post-money. Fighting the pool number from twelve percent to ten percent is worth almost two points of founder ownership.
The pool refresh is the single most negotiable and least negotiated line item in a Series A term sheet.
Series B: growth-round mechanics
Twenty months later the company raises twenty million at an eighty million post-money. The pool is topped back up to ten percent post. Founders are now at around thirty percent, seed at ten, Series A lead at seventeen, other Series A at two, pool at ten, Series B lead at twenty, other Series B at eleven.
The dilution per dollar has dropped — a bigger round bought a smaller percentage — but the pool refresh still bites. The lever that mattered here: whether the company took secondaries alongside the primary. A modest founder secondary at Series B typically does not affect the round math and reduces the personal pressure to sell later. Founders who could have done it and did not are the ones who most regret it.
Series C: the shape at scale
Thirty million at a two hundred million post-money, no pool refresh needed. Founders land around twenty-four percent between the two of them — twelve to fifteen percent each, depending on the original split.
This is roughly the shape most successful startups reach: founder equity between ten and thirty percent post-Series C, with the exact number determined mostly by three levers.
The three levers that actually move the number
First, seed valuations. The single highest-leverage decision a founder makes is what they raise seed money at. Every doubling of the seed cap is roughly six to eight points of ownership at exit.
Second, pool refresh sizing. Founders lose more equity to pool refreshes than to any single investor. Fighting the refresh number is worth as much as fighting the pre-money.
Third, secondaries. Founders who take modest secondaries at B and C reduce their personal risk without materially changing the outcome. Founders who wait until exit either sell too early to a strategic or ride out an IPO with concentrated personal exposure.
Where Equavion fits
Equavion's scenario modeler runs this exact math on your live cap table. Every raise is a scenario you can build on top of the current graph, with the pool refresh, the SAFE conversion and any secondary modeled explicitly. When a term sheet arrives, you can compare it against the current baseline in seconds — not against a stale spreadsheet copy.
Takeaways
- Founder ownership at Series C is usually ten to thirty percent, and the shape is determined mostly by three levers.
- The largest lever is seed cap. Every doubling is six to eight points of ownership at exit.
- The second largest lever is pool refresh. Fight the number as hard as you fight the pre-money.
- The third lever is secondaries. Modest, boring secondaries at B and C reduce personal risk without moving the outcome.
