A cofounder equity split is one of the first proper decisions a new business has to make, and it is also the one most founders rush through fastest. I have sat across the table from enough cofounder pairs, and been one myself more than once, to know that the fifty fifty handshake feels generous in the moment and turns into a grievance about eighteen months later. It is not a moral failing. It is just what happens when a decision made on excitement gets tested by actual work.
I am not against equal splits. Sometimes they are exactly right. What I am against is picking a number because it feels awkward to negotiate with a friend, then living with the consequences for the next ten years. Equity is not a gesture of trust, it is ownership of a company you both have to build and, eventually, might both want to leave.
Why the Fifty Fifty Split Feels Fair and Usually Is Not
Fifty fifty is the default because it avoids conflict at the exact moment nobody wants conflict. You have just decided to build something together, morale is high, and sitting down to argue about percentages feels like it undermines the whole thing before it has started. So people split down the middle and move on.
The trouble shows up later, when one founder is doing sixty hour weeks and the other has kept a day job for another six months, or when one person put in the redundancy money that paid for the first year of hosting and the other put in nothing. An equal split assumes equal contribution, and contribution is almost never equal for very long, even when it starts out that way.
What Actually Belongs in the Equity Conversation
Idea Versus Execution
Having the idea is worth something, but far less than most people think. I have started four businesses now, CampSuite, Crocodile HR, Lavida and RealCube, and in every single one the idea was the cheap part. Execution, the actual building, selling and surviving, is where the value gets created. Weight the split toward the people doing the work, not the person who thought of it in the pub.
Cash Committed and Risk Taken
If one cofounder is putting in savings, remortgaging a house, or walking away from a salary while the other keeps their job on the side for a while, that is a real and different risk profile. It does not automatically mean a bigger slice, but it absolutely belongs in the conversation, out loud, not assumed and left unsaid until someone brings it up during an argument.
Time Committed, Full Time Versus Part Time
This is the one that causes the most resentment because it changes over time and nobody revisits the split when it does. A cofounder who goes full time from day one is taking on more risk and doing more hours than one easing in around a day job. If that gap is going to close later, say so and agree how. If it is not going to close, the split needs to reflect that honestly rather than pretending everyone is contributing equally because the paperwork says so.
A Framework That Beats a Handshake
The approach I actually use with people I advise, including through my business consulting work, is simple. List out the inputs that matter for your specific business: idea, initial cash, ongoing cash, full time commitment, specific skills that would otherwise cost a salary to buy in, and existing customer or network access. Score each cofounder against each input honestly, weight the inputs by how much they actually matter for your business, and let the split fall out of the maths rather than out of a feeling.
It will not produce a perfectly clean number and that is fine. What it does is force the conversation to happen properly, with the awkward bits said out loud, rather than avoided because nobody wanted to be the one who brought up money on day one. Founders who have had this conversation properly argue far less later, because there is a documented reason for the split rather than a vague sense that it was always fifty fifty and now feels wrong.
Vesting Is Not Optional, Whatever the Split You Land On
Whatever percentage you land on, do not hand over the full equity on day one. Vesting over three or four years, with a one year cliff, protects everyone, including the person who thinks they will never leave. Cofounders leave businesses for all sorts of reasons, illness, a marriage that needs a house move, simply realising this is not for them, and none of those reasons are anyone's fault.
What is a genuine problem is a departed cofounder holding a large chunk of a company they stopped working on years ago, sitting on equity that a new hire or investor now looks at and wonders why it is still there. Vesting is standard practice for a reason, and skipping it because you trust each other is exactly the mistake that trust does not protect you from.
Put It in Writing Before You Need To
The single biggest mistake is treating the equity conversation as done once you have agreed a number verbally. Get a proper shareholders agreement drafted, covering the split, the vesting, what happens on a leaver, and how future decisions get made when you disagree. It costs money you would rather spend on the product, but it costs far less than the legal bill for unwinding a fallout with no agreement in place, which I have seen happen and it is genuinely miserable for everyone involved.
This is the same discipline I write about in The 28 Day Startup, get the unglamorous foundations right before the excitement of building takes over, because the foundations are what the business stands on when things eventually get difficult. They always do at some point, and a business with a proper agreement in place handles that moment completely differently to one running on a handshake.
My Honest Take
A cofounder equity split is not a test of how much you trust each other, whatever it might feel like in the moment. It is a business decision that deserves the same rigour as any other business decision, pricing, hiring, or picking a market. Have the conversation properly, weight it by real contribution rather than by what feels least awkward to say out loud, put vesting in place, and get it written down.
Do that and the split itself matters far less than most founders think. What actually protects the relationship is not the number, it is having had the honest conversation that got you to it.
