Plan biotech startup ownership with YC deal assumptions. Adjust dilution, SAFEs, notes, and option pools. See founder outcomes before fundraising conversations begin with confidence.
| Example Item | Value |
|---|---|
| Startup Focus | Biology platform startup |
| Founder Shares | 8,750,000 |
| Advisor Shares | 200,000 |
| Issued Employee Shares | 300,000 |
| Current Option Pool Shares | 900,000 |
| YC Ownership Percent | 7% |
| Convertible Dilution Percent | 4% |
| Pre-money Valuation | $10,000,000 |
| New Cash Raised | $2,500,000 |
| Target Pool Percent | 12% |
| Final Founder Ownership | 56.84% |
| Final Investor Ownership | 20.00% |
1. Initial fully diluted shares
Initial fully diluted shares = issued shares + current unissued option pool shares.
2. YC share issuance
YC new shares = initial fully diluted shares × YC percent ÷ (1 − YC percent).
3. Convertible dilution
Convertible shares = post-YC fully diluted shares × convertible percent ÷ (1 − convertible percent).
4. Option pool refresh
Pool top-up solves the shares needed to hit the target post-round pool after financing.
5. Share price
Share price = pre-money valuation ÷ pre-money fully diluted shares.
6. New investor shares
New investor shares = new cash raised ÷ share price.
7. Final ownership
Ownership percent = stakeholder shares ÷ final fully diluted shares × 100.
Biology startups often face longer research cycles. They also need larger early teams. That makes cap table planning more important. This Y Combinator equity calculator helps founders test ownership before a financing event. It estimates how YC equity, SAFE dilution, option pool changes, and priced rounds affect the final cap table.
Many founders focus only on valuation. That is not enough. Dilution also changes control, hiring power, and future fundraising leverage. A biology company may need lab hires, regulatory talent, and platform engineers. Each hiring plan can increase the option pool. This tool shows how that pool changes founder ownership after new money arrives.
The calculator works well for biotech, diagnostics, synthetic biology, medical device software, and research platform ventures. It gives a clean estimate of fully diluted ownership. It also highlights the share price used in a priced round. That helps founders compare scenarios side by side and communicate more clearly with investors and legal teams.
The result section reports initial dilution, YC shares, convertible impact, option pool top-up, investor shares, and final ownership percentages. Founders can see whether the round still leaves enough equity for retention and later financing. That is useful when building a hiring plan, negotiating pool size, or testing whether a term sheet still supports long-term incentives.
This tool is still an estimate. Real deals may include pro rata rights, liquidation preferences, multiple SAFEs, warrants, or special conversion rules. Even so, a structured estimate is valuable. It lets biology founders move from guesswork to a repeatable model. That makes investor meetings more informed and internal planning much stronger.
It estimates post-financing ownership for a biology startup. It models founder shares, YC dilution, convertible dilution, option pool expansion, and a priced round.
No. You can use it for any startup. The YC input is simply a configurable ownership percentage within the model.
Investors often ask for a larger hiring pool before or during a round. That change dilutes existing holders, so it should be modeled clearly.
No. It is a planning tool. Final dilution depends on signed documents, security terms, board approvals, and company counsel.
Yes. This version uses a single dilution percentage for other SAFEs or notes. It is fast for scenario testing.
Share price connects valuation and share issuance. It helps you understand how many new shares investors receive in the priced round.
Yes. It is useful before recruiting scientists, engineers, or lab staff because hiring plans often require more option pool capacity.
You can extend the file by adding more founder rows or extra financing steps. The same fully diluted logic can be reused.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.