SAFE conversion math, without the spreadsheet
A pocket SAFE conversion calculator for founders trying to figure out where they'll land after the next priced round.
A founder closing a priced round after a SAFE has converted should not be surprised by what ends up on the cap table. The math is not difficult, but most founders only see it for the first time when their lawyer sends the closing cap table, which is too late to renegotiate.
The SAFE conversion calculator on this site is a quick first pass. It takes the valuation cap, the SAFE amount, the discount rate, the upcoming round’s pre-money and new money, and the existing share count, then computes the conversion price, the shares issued to the SAFE holder, and the resulting ownership splits.
When to use it
At three moments. First, when you sign the SAFE: run the math against the smallest priced round you can imagine raising, and see what that looks like. Second, when a priced round is being negotiated: the calculator gives you a sanity check before you accept a term sheet. Third, when the closing cap table arrives: cross-check the lawyer’s output against the tool. The numbers should match within rounding.
What it does not do
It does not handle every SAFE variant. Post-money SAFEs (the YC default since 2018) work differently from pre-money SAFEs. The tool uses a simplified post-money treatment as the default and shows the option. It does not handle MFN provisions, side letters, multiple stacked SAFEs at different caps, or pari passu issues with prior notes.
For an actual transaction, the closing cap table is the source of truth, and that calculation should be run by your counsel against the actual SAFE form and the actual round documents. The calculator is for the conversation before then.
Walter Allison is a corporate attorney in Denver. He writes here about M&A, private equity, and venture capital structure.
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