The seed to Series B founder dilution map
Founders tend to model dilution one round at a time, which is why the Series B number is always a surprise. Dilution compounds: each round takes its percentage of whatever is left, not of what you started with. Step through the stages and watch it happen.
About the ranges. The per-stage figures are what published equity handbooks commonly report, not a dataset of our own — we have not run a survey. Every slider is yours to move, so the output is your assumption rather than our forecast, and real rounds vary widely by sector, geography and how competitive the raise was.
Your assumptions through Pre-seed
Added together, those percentages come to 20%. Compounded, founders are left with 80.8% rather than 80.0%. Each round takes its share of what remains, not of what you started with — which is why the gap widens with every stage.
Often SAFEs rather than a priced round, so the dilution lands later — at conversion, alongside the seed.
How much equity do founders typically give up by Series B?
Founder ownership compounds downward rather than subtracting. Published handbooks commonly report roughly fifteen to twenty-five per cent dilution per priced round, plus an option pool at each stage, so a sole founder often holds under half the company by Series B.
- Each round dilutes what remains, so four rounds of 20% leave about 41%, not 20%.
- The option pool is a second, separate dilution event at most stages.
- Ranges vary widely by sector, geography and how competitive the round was.
Why the Series B number always surprises people
Dilution multiplies, it does not add
Ask a founder what four rounds at 20% costs them and the instinctive answer is 80%. The actual answer is about 59%: each round takes a fifth of whatever is left, so 100 becomes 80, then 64, then 51.2, then 41. The intuition fails in the founder's favour early and against them late, which is exactly the wrong way round for planning purposes.
Add the option pool and the compounding runs twice per stage. A pool created at seed and topped up at Series A and B is three separate dilution events sitting alongside three investor rounds, and each one applies to a base the previous one already reduced.
The pool is the part founders forget to count
A new pool is normally carved out of the pre-money share count, which means the existing holders pay for it and the incoming investor does not. It is the single most common place a modelled round and an actual round diverge. The founder dilution calculator separates the two effects so you can see what the investor cost and what the pool cost, and the SAFE note conversion calculator handles the pre-seed case where the dilution is deferred until the paper converts.
What actually moves the number
Two things, mostly. Raising less at each stage — enough to reach the next milestone rather than the largest round on offer — and resisting pool sizes built for a hiring plan nobody has written. Neither is glamorous, and both compound in your favour across four rounds in exactly the way dilution compounds against you.
Where the standard terms come from
The pre-seed and seed end of this is largely governed by one instrument, and its mechanics are published rather than negotiated from scratch each time. Y Combinator's standard deal documents set out the post-money SAFE and how it converts, which is the step most pre-seed dilution models get wrong.
Keeping the running total honest is the part software should do. Lovie holds every round, pool top-up and outstanding SAFE against the same table, so the founder percentage on the screen is current rather than reconstructed the week before a board meeting.
Keep going
Before the round, the interactive term sheet decoder flags the clauses that change what a given valuation is actually worth. After it, AI-native vs legacy equity management covers keeping the table current without rebuilding it. The product is at Lovie CapTable.