The calculator walks you through a set of weighted questions about each co-founder's contributions: time commitment, idea origination, domain expertise, capital invested, and execution role. It scores each founder's inputs and returns a recommended equity percentage for each person.

The result is a starting point for the conversation — not a legal document. Once you've agreed on a split, the next step is to incorporate and issue shares with those percentages locked in from day one.

Most equity disputes happen because co-founders never explicitly discussed what each person was actually contributing. The factors that matter most are:

• Time commitment. A founder working full-time is contributing more than one working part-time — even if they joined at the same time. If one founder plans to go full-time immediately and another in six months, that gap should be reflected in the split.
• Idea and IP. The person who originated the core idea or contributed intellectual property at founding typically justifies a larger stake — but this factor is often overweighted. Execution matters more than the idea over time.
• Domain expertise. Technical, industry, or network expertise that is genuinely hard to replace has real equity value. A co-founder who is the only person who can build the product or open the critical customer relationships is not interchangeable.
• Capital contributed. If one co-founder is investing personal capital at founding, that contribution can be treated as equity rather than debt. Separate it from the role-based split so it doesn't distort the overall picture.
• Future responsibilities. Think about who will be doing what in 12 months, not just today. A 50/50 split that reflects equal effort now can create resentment later if roles diverge significantly.

For a deeper look at how these factors play out in practice, see our guide on founder vesting schedules and best practices.

• Equal split (50/50 for two founders, 33/33/33 for three). The most common arrangement and the simplest to agree on. It works well when both founders are contributing equally across all factors, working full-time from day one, and joining at the same time. When in doubt and contributions are genuinely equal, equal is usually right.
• Unequal split (60/40, 70/30). More appropriate when one founder is clearly the lead — the primary technical architect, the person with the network that opens the first customers, or the one who originated the core IP. A difference of 10–20 points is meaningful enough to reflect contribution without creating a dynamic where the minority founder feels like an employee.
• Weighted by contribution. Some founding teams use a point-based framework — assigning scores to each factor and converting totals to percentages. This is what our calculator does, and it's a useful method when the contributions are genuinely asymmetric or when there are three or more co-founders.

Regardless of which model you use, the most important companion decision is your vesting schedule. Agreeing on equity without vesting is how co-founder departures turn into lawsuits. The standard is a 4-year vesting schedule with a 1-year cliff — see our complete guide to founder vesting for why this matters.