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Founder equity split calculator
How to divide equity between co-founders is one of the first and hardest conversations in a startup. This calculator turns the factors founders usually weigh into a starting point for that conversation, not a final answer.
Score each founder from 0 to 10 on each factor. Weights reflect how much each factor usually matters.
| Factor (weight) | ||
|---|---|---|
| Full-time commitment ×3 | ||
| Idea and early work ×1 | ||
| Domain expertise ×2 | ||
| Building the product ×2 | ||
| Sales and fundraising ×2 | ||
| Money put in ×1 |
- Founder A
- 50.6%
- Founder B
- 49.4%
How it works
Score each founder from 0 to 10 on each factor. Each score is multiplied by the factor's weight, and each founder's share of the total points becomes their suggested equity. Full-time commitment carries the most weight, because equity is mainly a reward for the years of work ahead, not for the idea.
Example: two full-time founders, one strong on the idea and product, the other on domain expertise and sales, end up close to 51% and 49%. Small differences in contribution rarely justify a large gap.
Principles that help
- Weight the future over the past: most of the work is still to come.
- Put everyone's shares on vesting, typically four years with a one-year cliff, so the split stays fair if someone leaves.
- Treat money put in separately where possible, as a loan or an investment on the same terms as outside investors.
- Agree it early and write it down: the conversation only gets harder later.
Equal or unequal?
Many investors are comfortable with equal or near-equal splits between full-time founders, because they signal partnership. Large gaps can be right when contributions really differ, for example a part-time co-founder, or one who joins much later, but they should reflect future roles, not who had the idea.
Related reading: Vesting, cliffs and ESOPs: how startup equity is earned and What is pre-seed funding? Sources, size and what investors want.
Frequently asked questions
- Should co-founders split equity equally?
- Often, if they are joining full time at the same stage with comparable roles. Otherwise, an unequal split tied to future contribution and protected by vesting is common.
- How much equity should a late co-founder get?
- Less than the original founders, reflecting the risk already taken and progress made, and always on vesting.
- What if a co-founder leaves?
- Vesting means they keep only what they have earned; unvested shares return to the company, usually under the founders' agreement.
- Should investors' money count in the split?
- Usually not. Money a founder puts in is better treated as an investment or a loan on clear terms, so the founder split reflects work.
- Do we need a founders' agreement?
- Yes. Write down the split, vesting, roles, decision-making and what happens if someone leaves, and have a lawyer turn it into a shareholders' or founders' agreement.
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All calculators →Results are estimates for planning and learning, based only on the numbers you enter. They are not financial, tax or investment advice.