Weight the future heavily
Time commitment and execution ownership receive the strongest weights because ongoing company building creates most of the future value.
Founder ownership tool
Co-founder equity split calculator
Create a discussion starting point by comparing the future contribution and risk expected from two founders.
- Free to use
- Runs in your browser
- No details saved
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Enter your assumptions
This is a structured conversation aid, not a legal, tax, or valuation conclusion.
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This is a structured conversation aid, not a legal, tax, or valuation conclusion.
How to use this tool
Use the output as a decision prompt
Founder equity is a prediction about future contribution under uncertainty. The original idea, early work, cash, expertise, and traction can matter, but most value usually depends on years of execution after the split is discussed.
Score each factor for both founders based on expected responsibility and documented contribution. The calculator normalises the weighted totals into a percentage. Use the result to surface different assumptions, then design vesting and legal documents with qualified advisers.
Method and interpretation
What the calculation is designed to show
Separate effort from assets
Prior hours are not automatically company value. Consider validated learning, usable IP, contracts, revenue, or capital that genuinely transfers.
Protect uncertainty with vesting
A percentage alone cannot handle an early departure. Obtain advice on vesting, leaver terms, approvals, share issuance, and tax.
Useful applications
When this tool can help
Revisit the calculation when assumptions or evidence change. Keep the inputs with the result so another founder or adviser can understand the reasoning.
- Prepare an equity discussion
- Compare expected founder responsibilities
- Expose disagreement about prior value
- Model a two-founder starting point
- Support a plain-language term sheet
- Identify questions for professional advisers
Questions and limitations
Understand what the result cannot decide
Is the calculator result a fair legal equity split?
No calculator can determine legal fairness. The result is a discussion aid based on your inputs. Final ownership requires judgment, due diligence, vesting, documentation, approvals, and professional legal and tax advice.
Should the idea founder receive more equity?
An idea can contribute value when supported by evidence, IP, or traction, but the future work and risk often matter more. Avoid treating the idea alone as the majority of company value.
Why does the tool use a range?
Input scores are subjective and company building is uncertain. A range communicates that the result is a negotiation starting point rather than mathematical truth.
Can I use this for three or more founders?
This version compares two founders. For a larger team, assess the same factors across everyone and obtain cap-table advice because dilution, options, vesting, and governance become more complex.
Turn analysis into a founder conversation
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Create your profile and meet founders who can challenge the assumptions with you.
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