Equity dilution calculator
Multi-round simulator that models SAFE stacking, option pool placement, and anti-dilution scenarios in a single flow. No signup, no upsell. Edit the worksheet below and watch founder ownership decay from 100% through every round you raise.
Round-by-round dilution worksheet
The dilution formula
Your ownership after a round equals your shares divided by the new total share count. New shares come from two places: investor purchases at the round price, and option pool top-ups placed pre-money. Add them in, watch your slice shrink.
Dilution is multiplicative
Three rounds at 20% dilution each leave founders at 51%, not 40%. Each round dilutes what you have, not what you started with. The calculator above shows the running total so you do not need to do the multiplication in your head.
Pre-money pool gotcha
A 10% pool placed pre-money typically costs founders 3 to 8 points more ownership than the same pool placed post-money. Same headline number, very different real-world impact. See /option-pool for the side-by-side.
What is normal at each stage
| Stage | Median dilution | Typical raise | Pre-money | Founders retain (median, cumulative) |
|---|---|---|---|---|
| Pre-seed | 8.5% | $0.5–2M | $3–8M | 91% |
| Seed | 13.8% | $1–4M | $8–18M | 78% |
| Series A | 17.9% | $5–15M | $25–60M | 64% |
| Series B | 14.0% | $15–40M | $80–200M | 55% |
| Series C | 11.0% | $40–100M | $250–600M | 49% |
Source: Carta Q1 2025 round-stage data, Rebel Fund 2025 seed benchmarks, PitchBook 2025 valuation tracker. Ranges round to tidy values; the calculator above runs exact math.