Startup SAFE Note Dilution & Cap Table Calculator – YC Post-Money SAFE Conversion
Investment Amount / Post-Money Valuation Cap. Additional SAFEs dilute existing founders, NOT the earlier SAFE investors.
Understanding Startup SAFE Notes & Cap Table Dilution
The Simple Agreement for Future Equity (SAFE), created by Y Combinator in 2013 and updated to the Post-Money SAFE standard in 2018, is the dominant financing instrument used by early-stage tech startups to raise seed capital without the complexity and legal expenses of a negotiated priced equity round.
How Y Combinator Post-Money SAFEs Work
Unlike convertible promissory notes which accrue interest and carry maturity dates, a SAFE note is a warrant-like contract that converts into preferred shares when the company completes its next priced round (typically Series A):
- Valuation Cap: The maximum effective post-money company valuation at which the investor's money converts into equity. In a post-money SAFE, the investor's ownership is fixed at
Investment / Valuation Cap. - Founder Dilution Transparency: With post-money SAFEs, founders can calculate exactly how much equity they are selling with each signed check (e.g. $500k on a $5M cap sells exactly 10% of the company).
- Dilution Mechanics: Each new SAFE dilutes only the founders—it does not dilute previously issued post-money SAFEs.
The Option Pool Shuffle at Series A
When institutional venture capitalists lead a Series A priced round, term sheets typically mandate creating or expanding an Unallocated Employee Option Pool (usually 10% to 15%). Founders must ensure they understand whether this option pool is calculated pre-money (diluting only existing shareholders) or post-money.
Frequently asked questions
What is the difference between Pre-Money and Post-Money SAFEs?
Pre-Money SAFEs created ambiguity because an investor's ultimate ownership percentage depended on the total number of other SAFEs issued before the priced round. Post-Money SAFEs lock in ownership immediately upon signing.
Does a SAFE note carry voting rights or board seats?
No. SAFE holders do not own stock until conversion at a priced round, meaning they hold no voting rights, board governance seats, or statutory shareholder inspection rights.
What happens to a SAFE if the startup fails before Series A?
In the event of dissolution or bankruptcy, SAFE holders have liquidation preference ahead of common stockholders (founders and employees) but subordinate to bank loans and senior debt.
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