Free tool · No signup
Co-Founder Equity Split Calculator
Score each founder's contribution across five dimensions, then see a suggested split and a 4-year vesting schedule.
Suggested split
Vesting schedule
After the 1-year cliff, shares vest monthly over 4 years total.
Year 0
0%
Year 1
0%
Year 2
33%
Year 3
67%
Year 4
100%
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Next step
Turn the split into an agreement
See how YC founders structure vesting, cliffs, and departures before you lock these percentages into your cap table.
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How to use this tool
Step 1
Score each dimension
Rate each founder 0–10 on idea, code, sales, capital, and operations.
Step 2
Review the split
Use the weighted scores as a starting point for the conversation.
Step 3
Set vesting
Choose a 4-year vesting schedule with a 1-year cliff.
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FAQ
Should co-founders split 50/50?
YC's default advice is yes for two equal co-founders who are both all-in. Deviations need a clear, ongoing contribution difference.
What is a 4-year vesting cliff?
Founders earn their shares over 4 years. If someone leaves before the 1-year cliff, they get nothing. This protects the company and the remaining founders.
Does this calculator replace a lawyer?
No. Use it to start the conversation, then have a lawyer draft the actual founder agreement.
Is the cofounder equity split calculator free?
Yes, free and no signup. Everything is computed locally in your browser.
Should cofounder equity ever be exactly 50/50?
Often yes, especially when both founders are full-time from day one. Use the weighted split as a conversation starter, not a verdict.
Keep reading
Playbook
YC Equity Split for Co-Founders →
Why YC pushes 50/50 splits, when to deviate, and vesting basics.
Deep dive
The $500K YC Deal →
How the standard $125K + $375K SAFE actually works.
Playbook
YC Co-Founder Matching →
How to work YC's 150K+ profile platform to find a co-founder who ships.
Deep dive
The YC SAFE, Explained →
Post-money SAFE mechanics, cap tables, and what founders actually sign.
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