# Pro Rata Calculator | Follow-On Check Size > Find the check that keeps your ownership in a new round, what you own if you skip, and what a partial pro rata investment gets you. Free pro rata calculator. URL: https://raziel.co/tools/pro-rata-calculator Find the check that keeps your ownership in a new round, what you will own if you skip it, and what a smaller check gets you. ## Results Pro rata check to keep 2.00% $200,000 2.00% of the $10M round, buying 0.40% of the company at $50M post-money **Ownership if you skip** 1.60% Down 0.40 points **Ownership with your check** 1.80% $100K is 50% of your pro rata **Share the round sells** 20.0% $10M / $50M post-money **Pre-money valuation** $40,000,000 **Stake at post-money if you skip** $800,000 **Stake at post-money with your check** $900,000 Includes your $100K check Your ownership after the round 2.00% 1.60% 1.80% 2.00% TodayIf you skipYour checkFull pro rata - Your ownership Track pro rata in Raziel See your ownership in every company and plan follow-on checks before the round closes. [Start free](https://app.raziel.co/sign-up) The math ## How pro rata *works* Every priced round sells a slice of the company to new money, and everyone who already owns shares gets diluted by that slice. A pro rata right lets you buy back in. 1. **Size the round.** The round sells its size divided by the post-money valuation. That is how much everyone else shrinks. 2. **Take your share of it.** Buying your current percentage of the new shares (your ownership times the round size) exactly offsets the dilution. 3. **Or write a different check.** Any check buys check divided by post-money of the company, on top of your diluted stake. Round stake = round size / post-money Pro rata check = ownership x round size Ownership if skipped = ownership x (1 - round stake) Ownership with check = ownership if skipped + check / post-money ### Assumptions and simplifications - Your pro rata check is part of the round size, not on top of it. - No option pool increase, SAFE or note conversion in the round. Those dilute you further; see the option pool and SAFE conversion calculators. - Stake values use the post-money valuation, before any liquidation preferences. Worked example ### 2% owner, $10M round at $50M post-money **Round stake** $10M / $50M = 20.0% **Pro rata check** 2% x $10M = $200,000 **If you skip** 2% x 80% = 1.60% **With a $100K check** 1.60% + $100K / $50M = 1.80% Pro rata check**$200,000** ## Further reading - [Raziel Learn How to Track Pro-Rata Rights Across a Startup Portfolio](https://raziel.co/learn/pro-rata-rights-tracking) - [Raziel Learn The Importance of Follow-on Investments in Startups](https://raziel.co/learn/importance-follow-on-investments) - [Raziel Learn How to Track Super Pro Rata Rights in a Later Round](https://raziel.co/learn/super-pro-rata-tracking) ## Frequently Asked Questions Common questions about the Pro Rata calculator and the math behind it. ### What is a pro rata right? A right, usually in a side letter or the investor rights agreement, to buy enough of a future round to keep your percentage ownership. If you own 2% and the company raises $10M, your pro rata is 2% of the round, or $200,000. ### How is the pro rata amount calculated? Your current fully diluted ownership times the size of the new round. Buying that share of the new stock exactly offsets the dilution from the round, so your percentage stays the same afterward. ### What happens if I skip my pro rata? Your ownership falls by the share of the company the round sells. A round that sells 20% of the company takes a 2% holder to 1.6%. You keep the same number of shares, and if the round is priced up they are worth more on paper. ### Should I always take my pro rata? Not automatically. Following on concentrates more money in one company at a higher price. Many investors take pro rata in the companies that are clearly working and pass on the rest. This calculator shows the ownership math; the investment decision is yours. ### Does the option pool affect my pro rata? If the round also tops up the option pool before the new money comes in, you are diluted by the pool increase as well, and your pro rata check will not fully restore your ownership. Pro rata rights are usually defined on the new securities sold, not the pool. Use the option pool calculator to see that effect. Related tools ## More free *calculators* [All tools](https://raziel.co/tools) - [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) - [Startups and SAFEs SAFE Conversion Calculator Shares and ownership when a SAFE converts in a priced round. Open calculator](https://raziel.co/tools/safe-conversion-calculator) - [Startups and SAFEs Angel Portfolio Simulator Power-law outcomes, expected returns and odds of losing money. Open calculator](https://raziel.co/tools/angel-portfolio-simulator)