How to Split Equity Between Cofounders (Without Destroying the Company)

The equity conversation is the one founders dread most. It feels like putting a price on friendship. But not having it, or having it wrong, breaks more startups than bad product-market fit ever will.

The 50/50 Trap

Equal split feels fair. On day one, both of you are excited, both of you are committed, and both of you believe you will contribute equally forever. That rarely happens.

By month six, one person is coding 80 hours a week while the other is "doing business development," which mostly means reading TechCrunch and taking coffee meetings. The person doing the work starts to resent the split. The conversation gets harder every month you avoid it.

50/50 also creates deadlock. When you disagree on a big decision and nobody has a tiebreaker, nothing moves. That stalls companies.

What Should Influence the Split

The original idea matters less than people think. Ideas are cheap. Execution is everything. Do not give someone 50% because they "had the idea" while you built the product.

What actually matters: who is full-time versus part-time, who is putting in capital, relevant domain expertise and network, expected role going forward, and who could be replaced more easily. That last one is harsh but real. If the company cannot survive without the technical cofounder but could hire a replacement for the business cofounder, the split should reflect that.

Vesting Is Non-Negotiable

Whatever split you agree on, put it on a four-year vesting schedule with a one-year cliff. This is standard. Do it even between best friends. Especially between best friends.

The cliff protects everyone. If your cofounder leaves at month three, they walk away with zero instead of 6% of your company. Without a cliff, you are giving away equity to someone who contributed for a quarter and left you with the work.

You should also discuss acceleration clauses. Single trigger means vesting accelerates if the company is acquired. Double trigger means vesting accelerates only if the company is acquired AND the founder is let go. Double trigger is more common and more fair.

Realistic Examples

Have the Conversation Early

Do it in writing. Do it before you raise money. Do it before you build anything serious.

A lawyer costs $500 for a founder agreement. A lawsuit costs $50,000. And a failed cofounder relationship with no written agreement costs you the entire company.

If your relationship cannot survive an honest conversation about equity, it definitely cannot survive building a startup together. Think of it as the first real test.

Once you have agreed on terms, understand how fundraising instruments affect your ownership. And keep an eye on your runway so you know when dilution from your next round is coming.