Co-founder Equity Split Calculator
Distribute startup equity across co-founders in proportion to time, money, experience, and role criticality — a starting point for your co-founder agreement.
Factor Weights
Founders (2)
Results
Equity Distribution
Factor Breakdown
Inputs & Outputs
What the calculator takes, what it returns.
- Factor weights (4 × 0–100%) — time commitment, financial investment, relevant experience, role criticality. Aim for a total of 100%; the calculator normalizes any positive total and warns when the sum exceeds 100%.
- Per-founder time commitment (0–100%) — share of dedicated working time.
- Per-founder cash invested (USD) — absolute amount; normalized across founders.
- Per-founder experience & role scores (0–100% each) — subjective scores, ideally agreed together.
- Equity percentage per founder — normalized to sum to 100%.
- Per-factor contribution breakdown — how much of each founder's share came from each of the four factors.
- Visual pie chart — for shareable alignment with co-founders.
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Dividing equity is one of the most critical conversations co-founders will have. A fair process builds a strong foundation for your partnership, while an unfair split can lead to resentment and demotivation. This calculator is designed to guide an objective discussion based on tangible contributions, helping you reach an agreement that feels right for everyone.
The Core Factors Explained
Time Commitment
This factor accounts for the time each founder dedicates to the startup. A founder working full-time is taking on more risk and has a greater opportunity cost than someone contributing part-time. Be honest about your expected commitments—is this a full-time job, a side hustle, or something in between? The equity should reflect that level of dedication.
Financial Investment
While many startups are bootstrapped, any cash invested by founders is a significant contribution that reduces risk and accelerates growth. This factor gives weight to the capital each person puts into the business. It's a tangible measure of "skin in the game" that deserves to be recognized in the equity split.
Relevant Experience
This values the unique skills, expertise, and network each founder brings. A founder with deep industry knowledge, a track record of building successful companies, or critical technical skills provides immense value beyond just their time. Consider past successes and how relevant that experience is to your startup's mission.
Role Criticality
Not all roles are created equal, especially in the early days. This factor assesses the importance of each founder's primary responsibilities. For a deep-tech startup, the CTO's role might be more critical initially than the CMO's. Discuss which roles are most vital to overcoming your first major hurdles and assign weight accordingly.
Use this tool as a starting point for a conversation, not as a final verdict. The numbers provide a logical framework, but they don't capture everything. Have an open discussion, adjust the weights based on what you collectively agree is most important for your venture, and document your agreement. A fair split is one that every founder feels good about.
FAQ
How does the equity split calculator work?
You assign weights to four contribution factors — time commitment, financial investment, relevant experience, and role criticality — then rate each co-founder on those factors. The calculator normalizes the scores and returns a suggested equity percentage per founder. The four weights should sum to 100%.
Is the suggested equity split legally binding or a final recommendation?
No. This tool is a starting point for a structured conversation between co-founders, not a legal document or final verdict. Use the output to align expectations, then formalize the agreed split in a founders' agreement with a lawyer.
Should co-founders always split equity 50/50?
Not necessarily. Equal splits are common when founders contribute comparable time, capital, experience, and risk — but they can create resentment if one founder actually carries more of the load. A deliberate split based on contributions is usually healthier than a default 50/50, even when the numbers end up close.
How should I weight the four factors (time, money, experience, role)?
There is no universal answer — the right weights depend on your stage and what the startup actually needs to succeed. A bootstrapped, pre-revenue startup often weights time commitment highest. A capital-intensive venture may weight financial investment more. Deep-tech startups frequently over-weight role criticality for the technical co-founder. Discuss and agree the weights together before rating individuals.
What about vesting? Does the calculator handle that?
No — the calculator gives you the target split. Vesting is a separate (but essential) layer on top. Standard practice is a 4-year vesting schedule with a 1-year cliff for all founders, so someone who leaves early doesn't walk away with a large block of unearned equity.
Should we leave room for an employee option pool (ESOP)?
Yes, if you plan to hire early employees or raise external capital. Most priced rounds require a 10–15% ESOP carved out before the investment, which dilutes founders. You can model the founder split here and then reserve a separate ESOP pool at cap-table setup.
How do I account for a co-founder who joined later?
Reduce their time commitment score proportionally to when they joined, and be honest about the risk they avoided by joining after the idea was validated. Some teams also apply a dynamic equity model where the split re-calibrates as contributions change over time.
My co-founder and I disagree on the split — what now?
Disagreement at this stage is valuable — it surfaces misaligned expectations before they become real problems. Go through the four factors separately, each rate all founders independently, then compare. Large gaps usually point to an unspoken assumption about roles or commitment that needs to be discussed. If you're stuck, Build Up Labs offers mentor sessions to facilitate this conversation.
Is my data saved?
Yes, locally. Your factor weights and founder inputs are stored in your browser via localStorage so the values persist if you close the tab. Nothing is sent to our servers. Use the Reset to defaults button to clear your session.