Splitting founder equity with a model, not a fight
A weighted scoring tool that takes commitment, years, and capital contribution per founder and produces a starting-point equity split.
The cofounder equity split is one of the most consequential conversations a startup will have, and one of the most poorly handled. The default move — equal splits because it feels fair — ignores meaningful differences in commitment, time invested, and capital at risk. The result is resentment a year in, when one cofounder is full time and another is still doing consulting work on the side.
The founder equity split modeler takes the conversation out of "what feels right" and into "what does the math say". For each founder, enter three inputs: time commitment (full-time vs part-time vs advisor), years committed forward, and capital contributed. The tool weights each input, scores each founder, and produces a percentage allocation.
Why a model
The model is not the answer. The model is the conversation starter. Cofounders look at the output, react, adjust the inputs, and re-run. The conversation is now about the inputs (is your commitment really full-time? how much capital did you contribute?) rather than about who deserves what percentage in the abstract. The argument over abstractions becomes an argument over facts, which is a much better argument.
What the model does not capture
It does not capture the founder who brought the idea. Idea-as-equity is a contested topic and the tool does not take a position. If you believe the idea founder deserves a premium, add that as a separate adjustment after the model output.
It does not capture risk tolerance, network value, or domain expertise. Those are real, hard to quantify, and usually the right answer is to discuss them explicitly and apply a manual adjustment rather than to invent a number.
It does not capture vesting. The output is the allocation. Whatever you allocate, vest it over four years with a one-year cliff. The model says how much each founder gets; the vesting schedule says when.
The conversation it enables
The hardest part of the founder equity conversation is that it requires cofounders to talk about money before they have any. The model makes that conversation concrete. It forces specifics about commitment and capital, which are the things that actually predict equity fairness over time.
After the model output, write the allocation into the formation documents and move on. The right answer is the one the founders agree is fair given the facts. The model is the way to find that answer faster.
Walter Allison is a corporate attorney in Denver. He writes here about M&A, private equity, and venture capital structure.
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