Multi-Round Dilution Calculator
See how your ownership compounds down across every round - Seed to Series C and beyond, with option pool top-ups along the way.
Where you start
Your fully-diluted ownership today, before any of the rounds below.
Your rounds
Carved pre-money, so it dilutes existing holders only. Leave blank for none.
Carved pre-money, so it dilutes existing holders only. Leave blank for none.
Carved pre-money, so it dilutes existing holders only. Leave blank for none.
Your ownership, round by round
Each bar is your ownership after that round. The drop shows what the new investors and any pool top-up took from your slice.
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Dilution compounds - that's the part founders miss
A single round is easy to reason about: raise $5M at $20M pre, the investor owns 20%, you keep 80% of what you had. The trap is assuming the next round "costs" another 20 points. It doesn't. Dilution multiplies - it never simply adds.
The multiplying-down formula
For each round, work out the fraction of the company existing holders retain:
- Investor fraction = raise ÷ (pre-money + raise).
- Pool fraction = the new option pool, as a share of post-money (carved pre-money).
- Existing retention = 1 - investor fraction - pool fraction.
Your new ownership is your old ownership times that retention. Chain the retentions across every round and you get your final stake.
A worked example
Say you start at 40% after incorporation, then raise three times:
- Seed - $2M on $8M pre with a 10% pool: retention 70%. You go 40% → 28%.
- Series A - $10M on $30M pre with a 10% pool: retention 65%. You go 28% → 18.2%.
- Series B - $20M on $80M pre, no new pool: retention 80%. You go 18.2% → 14.6%.
You started at 40% and finished at 14.6% - keeping about 36% of your original slice. None of the individual rounds felt unreasonable; the compounding is what does the work.
Why this matters
- Raise less, less often when you can - every round you skip is a retention multiplier you keep at 1.0.
- Push pre-money - a higher pre-money shrinks the investor fraction directly, which protects every future round too.
- Right-size every pool- pool top-ups stack across rounds and hit founders alone. Asking for only what you'll grant in the next 18 months compounds in your favor.
This is an illustrative model, not financial or legal advice. It assumes standard priced rounds and pre-money pool top-ups, and does not model SAFE conversions, anti-dilution, or secondary sales.
Frequently asked questions
- How is dilution across multiple rounds calculated?
- Dilution compounds. Each priced round multiplies your ownership by the fraction of the company that existing holders keep - which is 1 minus the new investor's percentage minus any new option pool. If you keep 70% of the company after a round and 65% after the next, your ownership is multiplied by 0.70 then 0.65. Two 20% rounds don't dilute you by 40 points - they multiply down (0.8 x 0.8 = 0.64), so a 100% holder ends at 64%, not 60%.
- Why does the option pool dilute me more than the investor?
- A pre-money option pool top-up is carved out of the company's value before the new money goes in, so only existing holders pay for it. This calculator follows that convention - each round's pool percentage reduces existing-holder retention alongside the investor's stake, while the investor's percentage stays clean. That is the 'option pool shuffle,' and it repeats at every round that asks for a fresh pool.
- What does 'of your original stake, you keep' mean?
- It's your final ownership divided by your starting ownership. If you began at 40% and ended at 14.6%, you retained about 36% of your original slice - the rest went to investors and option pools across the rounds. It's a quick way to see how much of your founding position survives a full financing path.
- Does this model SAFEs, anti-dilution, or secondary sales?
- No - this is an illustrative model of standard priced rounds plus pre-money pool top-ups. It does not fold in SAFE or note conversions, anti-dilution ratchets, pay-to-play recapitalizations, or secondary sales. Those interact with the cap table in ways a single percentage can't capture. To model them precisely, build out the full cap table.
- How do I see this across every shareholder, not just me?
- This tool tracks one holder's percentage through a sequence of rounds. To project every founder, employee, and investor's ownership after each round - with real share counts, converting SAFEs, and exit waterfalls - model it on your actual cap table in Slyced.
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