equity
How to Split Equity Between Co-Founders
Splitting equity is one of those conversations founders put off, and it's usually the wrong thing to put off. Nobody really enjoys sitting down to decide who owns what this early. But it comes down to one honest question: does the split reflect what each person actually puts in over the life of the company, not just who had the idea first? You get there with a proper conversation, a simple way to weigh contribution, and a vesting schedule so the split on paper survives contact with reality.
Start with a conversation, not a spreadsheet
The equity split is really a conversation about expectations: who's going full time, who's taking a salary cut, who's bringing money, and who's carrying the most risk if the company fails. Skip that conversation and jump straight to a number, and you tend to bury the disagreements that come back later, usually at the worst possible time.
Talk through the uncomfortable parts early. What happens if one of you wants to leave in year two? What if one of you can't go full time for six months? What if the company pivots away from the original idea entirely? You don't need perfect answers, you just need to know you can have the conversation at all. If you can't agree on equity while you still like each other, that tells you something about the partnership.
Why an even split is common, and when it's a mistake
A 50/50 split is popular for good reasons. It signals equal partnership, it's simple, and when two founders really are joining at the same time with comparable skin in the game, it's often the right call. Plenty of founders reach for it, and the research on founding teams suggests the ones who stop to negotiate a bit more deliberately tend to be happier with it later.
The mistake is reaching for even because it's easy, when the situation isn't actually even. It's worth splitting more deliberately when:
- One founder started months or years before the other, and there's already real progress.
- One founder is going full time while the other keeps a day job for a while.
- One founder is putting in meaningful cash, not just time.
- The founders bring very different levels of relevant experience or risk.
None of these automatically means an unequal split. They just mean the split deserves a real conversation, not a reflex.
A simple framework for dividing equity
You don't need a complicated formula. You need a shared way to talk about contribution. Weigh a handful of things together and let the conversation, not the arithmetic, land on the number:
- Commitment. Who's full time, and from when? Time is the scarcest input in a startup.
- Risk. Who's giving up salary, stability, or other opportunities? Who signed the lease or the personal guarantee?
- Capital. Is anyone putting in money, and how much relative to the round they'd otherwise raise?
- Idea and early work. Who did the work that got the company to today? Weight the work, not just the spark.
- Ongoing value. Whose skills does the company most depend on over the next few years?
If you'd rather not do this by hand, the equity split calculator in the toolkit takes these same factors and gives you a starting percentage to adjust together.
Whatever it gives you is a starting point, not a verdict. Two reasonable founders can look at the same inputs and land in slightly different places. What you're after is a split you can both defend out loud a year from now.
Always put the equity on a vesting schedule
Whatever split you agree, put every founder's shares on a vesting schedule. Vesting means you earn your equity over time instead of owning all of it on day one. The standard is four years with a one year cliff: you vest nothing for the first year, then a quarter of your shares vest at the one year mark, and the rest vest monthly over the following three years. There's more on how the cliff works in founder vesting explained.
This protects everyone, including you. If a co-founder leaves after five months, vesting means they don't walk away with a quarter of the company for a few months of work, leaving the rest of you to build on a diluted cap table for years. It's not about distrust. It's the thing that lets you trust each other, because it keeps the deal fair no matter who ends up leaving.
The person most likely to resist vesting is often the one who most needs it later. If a co-founder refuses any vesting at all, treat that as a serious conversation about commitment, not a paperwork detail.
Write it down before you build
A handshake isn't a founders agreement. Once you've agreed the split and the vesting terms, put them in writing and sign them before you do any real work together. A short founders agreement should cover the equity split, vesting, what happens if someone leaves, how decisions get made, and how intellectual property is assigned to the company.
Deciding all of this while the company is still worth nothing is easy and calm. Deciding it after the company has real value, real customers, or a term sheet on the table is where friendships and companies break. Do the hard part first, while it's still the easy part.
Frequently asked questions
- Should co-founders always split equity 50/50?
- Not automatically. An even split is a fine default when founders join at the same time, take similar risk, and contribute comparable value. When those things differ a lot, have the conversation rather than defaulting to even just to avoid it.
- What is a normal vesting schedule for founders?
- Four years with a one year cliff is the common standard. Nobody keeps founder shares in the first year, and after the cliff the equity vests monthly over the remaining three years.
- Should you split equity before or after you start building?
- Agree the split and sign a founders agreement before you do significant work together. Deciding later, once there's real value on the table, is where most co-founder disputes begin.