How to Split Equity Between Co-Founders: The Complete Framework

The equity conversation is one that many founding teams avoid until it becomes unavoidable — by which point relationships are already strained. Getting ahead of it with a clear framework and the right tools is one of the best things a founding team can do in its first ninety days.

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Start with Contribution, Not Roles

The most common mistake is splitting equity by title: "I'm the CEO so I get more." Roles describe authority; they don't describe value creation. A technical cofounder writing the entire product might generate more value in year one than a business cofounder still finding product-market fit. Equity should track actual contribution — time, capital, IP, and resources — not org-chart position.

The Four Variables That Actually Drive a Fair Split

Every equity split comes down to four inputs: (1) time commitment — full-time vs. part-time, and for how long; (2) capital contributed — cash invested or assets transferred; (3) opportunity cost — what each founder is giving up to do this; (4) prior contribution — who built the prototype, who secured the first customer. Weight these honestly before opening a negotiation.

  • Time commitment — full-time vs. part-time, and for how long
  • Capital contributed — cash invested or assets transferred
  • Opportunity cost — what each founder is giving up to do this
  • Prior contribution — who built the prototype, who secured the first customer

Fixed vs. Dynamic: Choosing the Right Model

Fixed splits (60/40 or 50/50) are simple and legally clean, but they freeze the answer on day one. Dynamic splits — such as the Slicing Pie model — let equity float based on ongoing contributions, which is fairer when cofounders have different levels of availability or join at different times. Equafy supports both models and lets you combine them: lock in a base for each founder and let the rest accumulate dynamically.

Fixed splitDynamic splitEquafy
Set whenDay one, then frozenFloats with ongoing contributionsFixed base + dynamic remainder
Simple and legally cleanYesRequires ongoing trackingYes — both models combined
Handles unequal availabilityNoYesYes
Handles founders who join laterNoYesYes

The Reserved Pool: Don't Forget Future Hires

A common oversight is failing to carve out equity for future employees and advisors at the founding stage. Setting aside 10-20% before the split is negotiated means future dilution is shared equally rather than falling disproportionately on whoever holds the most equity. Equafy lets you configure a reserved pool as a separate allocation from the moment you set up your cap table.

10-20%set aside for future employees and advisors before the founder split is negotiated, so dilution is shared rather than falling on one founder.

Protect Everyone with Vesting

Whatever split you agree on, wrap it in a vesting schedule. Standard founder vesting is four years with a one-year cliff: nothing vests before twelve months, then the rest vests monthly. Vesting protects all cofounders — if someone leaves early, they don't walk away with a disproportionate chunk. Equafy manages vesting grant tracking so you always know who has vested what.

The standard founder vest

Four years with a one-year cliff: nothing vests before month twelve, then the rest vests monthly. It protects every cofounder — if someone leaves early, they don't walk away with a disproportionate chunk.

Frequently Asked Questions

Build your co-founder equity agreement on solid ground.

Equafy gives founding teams a shared, transparent cap table — with fixed allocations, dynamic contributions, and vesting built in from day one.

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