The default cofounder split in early-stage startups is fifty-fifty, and most experienced investors will tell you privately that it is the single most predictable cause of preventable founder breakups. The split feels equitable on day one because the work is shared and the future is unknowable. It stops feeling equitable around month eighteen, when the work is no longer shared and the futures of the founders have diverged.
The contrarian position, which is also the empirically supported one, is that thoughtful asymmetry produces healthier companies than reflexive equality.
Why “fair” on day one isn’t fair on day 700
Founders typically split fifty-fifty because no one can prove they’ll contribute more, and proposing anything else feels like a power grab. But cofounder contributions diverge fast. One person turns out to be the visionary; the other turns out to be the operator. One puts in seventy-hour weeks; the other has young kids and works fifty. One raises the money; the other ships the product. Within two years, the gap between actual contribution and equity ownership is often dramatic.
When the gap gets large enough, the higher-contributing founder feels exploited and the lower-contributing one feels scrutinized. Neither feeling is fully wrong. The original split, designed to avoid awkwardness, has produced exactly the resentment it was supposed to prevent. By then, fixing it requires renegotiation under emotional pressure, which is when relationships actually break.
Asymmetry, properly structured, prevents the fight
The healthiest splits are unequal in a way that reflects realistic differences in contribution, risk, and role. A founder who quit a senior job to work full time deserves more equity than one who kept consulting on the side. A founder who put in real capital deserves more than one who put in zero. A founder serving as CEO with the resulting accountability arguably deserves a small premium over peers in functional roles.
The numbers don’t have to be dramatic. A 60/40 split, or a 45/35/20 across three people, signals that the founders had a real conversation about contribution and made a deliberate choice. The signal matters more than the percentages, because it sets a precedent that future contribution mismatches will be discussed rather than absorbed.
Vesting and cliffs do most of the protective work
Whatever the split, the actual safeguard is a four-year vesting schedule with a one-year cliff and clear treatment of unvested shares on departure. This is the lawyer-recommended baseline for a reason. It means that a cofounder who leaves in month nine takes no equity, and one who leaves in year two takes only what they’ve earned. Without vesting, an early breakup leaves a non-contributing founder owning a large slice of every future round.
Vesting is non-negotiable. Splits are a conversation. Equal splits without vesting are a future lawsuit dressed in optimism.
Bottom line
Equal cofounder equity is the path of least resistance and the path of greatest later regret. Have the uncomfortable conversation about contribution before you incorporate, document it, and put real vesting in place. The founders who do this stay friends.
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