# Startup Dilution Calculator | Founder Ownership > Model up to four funding rounds with option pool top-ups and see founder and investor ownership after each round. Free startup dilution calculator. URL: https://raziel.co/tools/dilution-calculator Model up to four future rounds with option pool top-ups and see what founders and each group of investors own after every round. ## Results Founder ownership after Series B 42.1% Down from 90.0% today, a loss of 47.9 percentage points. **Founders’ stake on paper** $63,106,061 At the $150M post-money **Share of founder stake given up** 53.3% **All investors combined** 47.9% **Total raised** $43,000,000 **Last post-money valuation** $150,000,000 **Option pool at the end** 10.0% Ownership after each round 90%10% 70%10%20% 53%12%15%20% 42%10%12%16%20% TodaySeedSeries ASeries B - Founders - Option pool - Seed investors - Series A investors - Series B investors | Round | Post-money | New money | Pool top-up | Founders | | --- | --- | --- | --- | --- | | Seed | $15M | 20.0% | 2.2% | 70.0% | | Series A | $50M | 20.0% | 4.4% | 52.9% | | Series B | $150M | 20.0% | 0.5% | 42.1% | Run your cap table in Raziel Keep your cap table, investor pipeline and updates in one place before the next round. [Start free](https://app.raziel.co/sign-up) The math ## How dilution *adds up* Every priced round issues new shares. Nobody loses shares, but everyone who already owns a piece ends up with a smaller percentage of a bigger company. 1. **New investors buy their stake.** They own the raise divided by the post-money valuation (pre-money plus the raise). 2. **The option pool gets topped up.** If the existing unissued pool would end the round below the target, new pool shares are created before the round so the pool lands exactly on the target. 3. **Everyone else shrinks pro rata.** Founders, earlier investors and the old pool all scale down by the same factor, and the next round starts from there. The chart stacks each group's ownership after every round so you can watch the founders' share shrink and each new investor class appear. The worked example uses the default inputs ($3M seed, $10M Series A, $30M Series B). New investor stake = raise / (pre-money + raise) Pool top-up T = (target - pool x (1 - stake)) / (1 - stake - target) Each holder keeps = (1 - stake) / (1 + T) of their percent ### Assumptions and simplifications - Priced equity rounds only. SAFEs and notes are not converted here; include them in earlier investors or use the SAFE conversion calculator. - The pool target is the unissued pool after the round. Grants made between rounds are not modeled, so the pool only shrinks through dilution. - Existing investors are assumed not to buy into later rounds (no pro rata participation), and there are no secondary sales, down-round protections or warrants. - Founders’ stake “on paper” is ownership times the last post-money valuation, before any liquidation preferences. Worked example ### Seed: $3M on a $12M pre-money **New investor stake** $3M / $15M = 20.0% **Pool without a top-up** 10% x 80% = 8.0% **Pool top-up (as % of post)** 2.22% **Founders keep** 90% x 77.78% = 70.0% **After Series A** 52.9% **After Series B** 42.1% Founders after Series B**42.1%** ## Further reading - [Raziel Learn Understanding Option Pools and Their Impact on Early Investors](https://raziel.co/learn/option-pools-investor-equity-impact) - [Raziel Learn How Angels Should Read a Cap Table (Fully Diluted, SAFEs, Option Pool)](https://raziel.co/learn/startup-cap-table-for-angels) - [Raziel Learn Understanding Cap Tables and Their Impact on Investment Decisions](https://raziel.co/learn/understanding-cap-tables-investments) ## Frequently Asked Questions Common questions about the Dilution calculator and the math behind it. ### How much dilution is normal per round? Each round sells new investors a slice equal to the raise divided by the post-money valuation, so a round that raises $3M at a $15M post-money sells 20%. The option pool top-up comes on top of that. Rather than relying on a rule of thumb, plug in the raise and valuation you expect and see the result for each round. ### Why does the option pool top-up dilute founders but not new investors? Term sheets usually ask for the expanded pool to be created before the new money comes in, so it counts in the pre-money share count. That lowers the price per share for the new investors and leaves the whole cost of the top-up with the existing holders. This calculator models the top-up that way. ### Does dilution mean my stake is worth less? Not necessarily. Dilution lowers your percentage, but if the round is priced above the last one, each share is worth more and a smaller slice of a larger company can be worth more on paper. The calculator shows the founders’ stake at the last post-money valuation for that reason. ### Are SAFEs and convertible notes included? Not directly. If SAFEs or notes will convert at the first priced round, leave room for their expected ownership in the "earlier investors" share (100% minus founders and the pool), or use the SAFE conversion calculator first to estimate it. Anti-dilution adjustments and down rounds are not modeled. ### How do I model a round I am not sure about? Set its raise to zero and it is skipped. Every field is saved in the page URL, so you can copy the link for each scenario and compare them side by side. Related tools ## More free *calculators* [All tools](https://raziel.co/tools) - [Founders Runway Calculator Months of cash left and the date it runs out. Open calculator](https://raziel.co/tools/runway-calculator) - [Founders Option Pool Calculator How a pre-money option pool shrinks your effective valuation. Open calculator](https://raziel.co/tools/option-pool-calculator) - [Startups and SAFEs Startup Valuation Calculator Pre-money, post-money, price per share and dilution for a round. Open calculator](https://raziel.co/tools/startup-valuation-calculator)