Cofounder Equity Split Calculator
Splitting equity is one of the first hard decisions cofounders make — and getting it wrong quietly damages startups for years. This calculator turns the conversation into numbers: score each founder on what actually drives a fair split, and see a defensible percentage you can both stand behind.
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Methodology
How it works
How the equity split is calculated
Each founder is scored from 0 to 10 across six contribution factors. Every factor carries a weight reflecting how much it should influence a fair split. A founder's raw score is the sum of their factor scores multiplied by each factor's weight; their equity percentage is that raw score as a share of the whole team's total.
Nothing is hidden: the weights are shown on screen and fully adjustable, and the math is simple multiplication and division. Sensible defaults are provided, but every team is different — if the idea matters far less than the work on your project, drag its weight down and the build up. That transparency is the point — the output is only useful if both founders understand and accept how it was produced.
Why time and commitment weigh the most
Across the established frameworks (Frank Demmler's "Founders' Pie" and Mike Moyer's "Slicing Pie"), the single biggest driver of fair equity is ongoing, full-time commitment — not the original idea. Ideas are cheap; years of full-time execution are not. That's why "Time & commitment" carries the highest default weight here, and "Idea & origination" carries one of the lowest.
Capital invested and risk taken (the salary and stability a founder gives up) matter too, but they're bounded — a one-time cash contribution shouldn't outweigh someone building the company day in, day out.
Treat the result as a starting point — then add vesting
Use the percentage as an informed anchor for the conversation, not a verdict. Adjust the scores together until the split reflects reality, and always put the agreed split on a vesting schedule (typically four years with a one-year cliff) so equity is earned over time, not granted upfront. Then capture it in a written cofounder agreement.
FAQ