Practical guide
Post-money SAFE ownership: investment divided by cap
Estimate a capped post-money SAFE ownership scenario and understand why the signed instrument controls conversion.
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How is post-money SAFE ownership estimated?
For the simplified capped post-money scenario in this tool, modeled ownership equals investment divided by the post-money valuation cap. This is a planning shortcut for a specific instrument structure, not a universal conversion formula for every SAFE.
A hypothetical cap example
Assume a $500,000 investment and a $10 million post-money cap. The ratio is $500,000 ÷ $10 million = 5%. If the cap were $8 million with the same investment, the modeled percentage would be 6.25%.
Enter the investment and cap in the same currency. No currency conversion is performed. A number expressed in thousands in one field and full units in the other can produce a dramatically wrong result while still being valid arithmetic.
What the percentage represents
Y Combinator’s official materials distinguish post-money SAFEs from other instrument structures and describe conversion into shares during a priced round. The simple ratio should therefore be treated as a modeled ownership relationship under the chosen cap assumption, not as shares already issued today.
Keep the exact document version and the relevant capitalization definition with your scenario. The calculator has no fields for discounts, multiple outstanding instruments, pro rata participation, or later financing terms. It cannot infer them from investment and cap alone.
SAFE questions
Can I use a pre-money cap in this tool?
Do not assume the same shortcut applies. The input is explicitly a post-money cap. A pre-money instrument requires its own capitalization and conversion analysis.
Is the valuation cap the company’s guaranteed value?
No. The input is a contractual modeling parameter for this calculation, not a market valuation or a guaranteed exit price.
What happens after a priced round?
Later share issuance can change the final percentage. Model that separately only after understanding how the SAFE converts under the signed terms. This article uses hypothetical arithmetic and does not replace review of the financing documents.
Use the safe calculator to reproduce the scenario with your own inputs.