Get a starting point for dividing a startup between co-founders. Weight what matters (the idea, time commitment, role, risk taken and cash invested), score each founder, and see a suggested split, a factor-by-factor breakdown and a founding cap table with an option pool.
Last updated:
Number of founders
%
Set aside before splitting; 0 for none
Factor weights (how much each factor matters, total ideally 100)
%
Who came up with the idea, wrote the plan or brought patents/code
%
Full-time vs part-time, hours per week
%
CEO / CTO duties, domain expertise, key relationships
%
Salary given up, job left, personal guarantees
%
Cash put in (entered in money, shared pro rata)
Founder 1
$
Founder 2
$
Founder 3
$
Founder 4
$
Founder + pool shares, e.g. 10,000,000
Enter your values to see the result.
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How to use the Founder Equity Split Calculator
Choose the number of founders and the option pool to reserve for future employees.
Set the factor weights to reflect what matters most for your company (time and role usually matter most).
Score each founder from 0 to 10 on idea, time, role and risk, and enter the cash each has invested.
Press Calculate equity split to see each founder's percentage, shares and the factor breakdown.
Discuss and adjust the scores together, then put the agreed split on a vesting schedule.
How the weighted split is calculated
Founder share = Σ over factors (factor weight ÷ total weight × founder score ÷ sum of all founders' scores for that factor)
Example with weights idea 10, time 30, role 25, risk 15, capital 20: if Alex scores 8 on idea and the three founders' idea scores add up to 15, Alex gets 10% × 8 ÷ 15 = 5.33 points from the idea factor. Cash works the same way with dollars: $30,000 out of $50,000 invested earns 60% of the capital weight, 12 points. Adding every factor gives Alex's share of the founder stake; multiplying by (100% − option pool) gives the share of the whole company.
Suggested scoring guide
Factor
0–3
4–7
8–10
Idea & IP
Joined an existing idea
Shaped the concept and plan
Originated it and brings code, patents or customers
Time commitment
Nights and weekends, advisory
Part-time, 20–30 hours
Full-time from day one
Role & responsibility
Supporting role
Leads one function
CEO / CTO-level ownership of the company's success
Risk taken
Keeps a full salary elsewhere
Reduced income
Left a job, no salary, personal guarantees
Tips for a fair split
Agree on the weights before anyone scores, so nobody tunes the factors to favor themselves.
Score each founder separately, then compare and discuss gaps of more than two points.
Use vesting (often 4 years, 1-year cliff) and a founders' agreement so the split adjusts automatically if someone leaves.
Revisit the split only before shares are issued; after that, changes require transfers or new grants.
Frequently asked questions
How does this founder equity split calculator work?
Each factor gets a weight (for example time 30%, role 25%, capital 20%, risk 15%, idea 10%). Within each factor, its weight is shared among founders in proportion to their scores, or to their cash for the capital factor. A founder's equity is the sum of their shares across all factors, so the results always add up to 100% of the founder stake.
Should co-founders split equity equally?
An equal split is common and can be the right answer when founders start at the same time, work full time and take similar risks, because it signals partnership and avoids long negotiations. When contributions clearly differ, for example one founder is part-time or invests most of the cash, a weighted split like this one is easier to defend.
Why does the idea get a low weight?
Most of a startup's value comes from years of execution rather than the original idea, so many founders give the idea a modest weight. If the idea comes with real assets, such as working code, patents or signed customers, raise its weight or reflect those assets in the score.
What is an option pool and should founders reserve one?
An option pool is a block of shares set aside for future employees and advisers. Investors usually ask for one, often around 10% to 20%, before a seed or Series A round. Reserving it at founding shows everyone how much of the company the founders will hold after it is carved out.
What is founder vesting?
Vesting means founders earn their shares over time, typically monthly over four years with a one-year cliff, so a founder who leaves after six months does not keep a large stake. Combined with a fair split, vesting protects the remaining founders and is expected by most investors.
Should cash investment be treated as equity in the split?
Small amounts of cash used to get started are often counted as a factor in the split, as here. Larger amounts are frequently better handled as a separate investment, such as a convertible note or SAFE, or as a loan, so that cash and work are valued separately.
Is the calculator result legally binding?
No. It is a structured way to start the conversation. Record the agreed split, vesting terms and IP assignment in a founders' agreement and stock purchase documents prepared with a lawyer.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.