Question 1

Is 50/50 always fair?

Accepted Answer

Carta's Founder Ownership Report 2026 finds that most founding teams with more than one member do not give each founder an equal share, though the practice is becoming more common: even splits rose to 27.3% of three-founder teams last year, up from 21%, and to 16.7% of four-founder teams, up from 10.8%. Equal works when contributions genuinely are equal: same time commitment, similar skills, comparable risk. It breaks down quickly when one founder works full-time while another is part-time, or when one puts in materially more capital. Run the calculator and check how the recommendation lines up with your intuition.

Question 2

Should co-founders vest?

Accepted Answer

Yes. Always. Even between best friends. A four-year vest with a one-year cliff protects all of you if someone needs to leave. Without vesting, a co-founder who quits in month three keeps their full equity stake forever. With vesting, their unvested shares return to the pool. This is not paranoia, this is the version of fair-future-you both want.

Question 3

What if a co-founder leaves before vesting?

Accepted Answer

If you have proper vesting documented (reverse vesting agreement or share restriction agreement), their unvested shares are forfeited and either returned to the company treasury or redistributed. If you do not have vesting documented, they keep all their shares and your cap table is permanently distorted. Document vesting before you incorporate.

Question 4

What is the Slicing Pie method?

Accepted Answer

Slicing Pie is a dynamic equity split where each founder's slice grows based on tracked contributions (hours, capital, IP) until a fundraising event freezes the split. It works for very early-stage teams with uncertain contributions. It breaks down once roles solidify because the tracking overhead becomes punishing. Most successful startups end up locking in a static split early.

Question 5

How does the equity split affect my dilution later?

Accepted Answer

Your starting percentage flows directly into how dilution lands on you personally. If you have 60% and your co-founder has 40%, a Series A that takes 22% of the cap table dilutes you to 47% and them to 31%. The percentages stay proportional but the absolute drop is bigger for whoever started with more. Run your post-split numbers through the homepage calculator.

Question 6

Can I change the split later?

Accepted Answer

Yes, but it is awkward and tax-implicating. Founders sometimes redistribute equity through share buybacks, repurchases, or new grants that shift ownership. All of these have tax consequences and require legal documentation. The cleaner approach is getting the split right at incorporation. Use this calculator before you sign the founders' agreement.

Co-founder equity split calculator

Weighted contribution split

Vest, even when it feels unnecessary

What to talk through before you split

Co-founder split FAQ