Founder equity splits: the math that outlives the friendship
Equal is the default split for equal founders, and vesting is the rule that makes any split fair. The common mistakes, the advisor pool, and the what-ifs nobody asks during the founding week.
TL;DR: Founders who are equal in hours get equal equity — that is the default that closes the argument. Vesting is the real contract: four years, one-year cliff, written down on day one. The uneven split is earned by visibly different contributions, agreed out loud. The split should settle in one coffee; the vesting is what makes it last.
Why equal is the default
Two people, same risk, same hours, same stage — equal is not generosity, it removes the longest fight. The 60/40 split rarely survives the first year of contrasting ambition. Equal removes the game theory; the founders spend the year building instead of negotiating who deserves more.
What the split is really about
The split is a forecast of contribution, and forecasts are made before the work exists. The founder who has the idea, the one who builds, the one who sells — each expects to be the most important person in year three. Since no one can measure year three in week one, the equal default is the only forecast both can agree to with a straight face.
When uneven is honest
Uneven is fair when the record is visible: one founder brought months of customers, the other starts at week zero. Then 70/30 is not an insult, it is an accounting of the state of the company at founding time. The rule: the uneven number must be said out loud, written in a doc, and dated. Uneven splits that are whispered become clean breaks.
The clause that does more than the number
All founder equity vests: four years, one-year cliff, applied the same to everyone. The cliff handles the early-leaver: at month nine, nothing; at month fifteen, the amount already vested. The vesting handles the rest: the cap table stays clean, the company holds the unvested pool, and when the investor asks "who owns what," the table answers with math, not story.
The pools you keep separate
- The employee pool: usually ten to fifteen percent, included in the math before the round.
- The advisor pool: small grants, around one percent, on a two-year vest.
- Accelerator and board seats: minutes, not percentages.
Keeping the pools separate is the discipline that keeps the split itself honest.
The conversation nobody has
Before either party signs, walk through three scenes out loud:
- One founder leaves in month eleven.
- The product gets traction and then the market shrinks.
- Both want different things when the round comes.
The answers nobody gives — who else decides, what happens if a founder leaves, who sets the value — are the ones that decide the company later. The founders who ask these first are not the ones who end up in the spreadsheets.
The split is the one equity table you decide without lawyers in the room. The numbers that arrive with the lawyers — the term sheet and the SAFE — are where the rest gets paper via the round, and understanding the cap math is understanding which share the round leaves for you.
Frequently asked questions
What is a fair split between two cofounders?
Equal is the default when two founders join full-time at the same time: same risk, same hours, same title. Uneven is fair only when the record is visibly uneven, and even then it must be said out loud and agreed to.
What is the most common equity mistake?
Dividing equity without vesting. Equity is earned over time, not granted on day one. Without a schedule, a cofounder who leaves early takes the ownership of a company they no longer build.
What does a vesting schedule mean for founders?
Four years with a one-year cliff is the standard. Nothing vests in the first year; after that, equity vests monthly. A co-founder who leaves at month six exits with nothing, and the company keeps the ownership for the people who stay.
Do advisors get equity?
Sometimes, from a separate small pool kept outside the founder split. A typical advisor grant is around one percent, over two years of vesting. Mixing advisor shares into the founder numbers is how round-the-canvas fights begin.