🤝 Founder Equity Split Calculator
The lazy answer is a 50/50 handshake, and it wrecks more startups than any competitor does, because six months in, one person has done 80 percent of the work and resentment sets in. A fair split weighs what each founder actually brings across five things: the idea, the money, the full-time work, the expertise and network, and the risk they carry. Enter your share of each and see a split you can both defend later. This is for two co-founders (you and one partner).
Who conceived it and built the first version? Your percentage; your partner gets the rest.
Who is actually building this day to day? This is weighted the heaviest, because sweat over years dwarfs the starting gun.
Who is giving up more (a salary, savings, security) to do this?
Your equity
50%
Your partner's equity
50%
The math lands near an even split (50/50), and here that is earned, not lazy: you are contributing roughly equally across idea, money, work, expertise, and risk. Write it down anyway, with vesting, so today's fairness survives tomorrow's surprises.
Estimates for planning, not financial advice. Your real numbers will vary; that is exactly why you track them.
Does this resonate?
Getting the split right is a founder decision worth help
Equity is one of the few choices that is painful to undo. If you are standing up a business with a partner, Dee works through the real founder decisions with you before they harden.
Talk it through with Dee →Good questions about this math
Why is the full-time work weighted the most?
Because a company is built over years, not conceived in a moment. The idea matters, but ideas are cheap next to the thousands of hours of execution that turn one into a business. Weighting the ongoing work heaviest protects the person actually building, which is usually where splits go wrong.
What is vesting and why does everyone say I need it?
Vesting means each founder earns their equity over time (commonly four years with a one-year cliff) instead of owning it all on day one. It is the single most important protection in any split: if a co-founder walks after three months, vesting means they leave with a small slice, not a third of your company forever.
Is 50/50 ever right?
Yes, when two founders genuinely contribute equally across the board. The danger is not the number; it is choosing it to avoid an awkward conversation. If the honest math lands near even, a 50/50 with vesting is fine. If it does not, forcing it plants resentment that surfaces exactly when the stakes get high.
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