What a fair split reflects
Equity between co-founders should reflect relative contribution and commitment — who is full-time vs part-time, who brings the idea, the technical build, the capital, the network, and who carries the most risk. The idea alone is worth far less than the years of execution, so ‘I thought of it’ rarely justifies a large majority. Have the honest conversation early.
Equal isn't automatically right or wrong
An equal split can be fair where contributions truly are equal — but a default 50/50 done to avoid an awkward conversation is a common mistake that causes resentment later. Whatever you agree, the real protection is vesting — so a founder who leaves early doesn’t walk away with a big unearned stake. Document the split and vesting before significant work begins.
A worked example
Example: two founders — one full-time technical, one part-time keeping a job — agree 65/35 rather than a reflexive 50/50, and put it in a founders’ agreement with 4-year vesting. When the part-time founder leaves after a year, only their vested portion stays, protecting the company. The split conversation plus vesting prevents the classic co-founder fallout. Our team can help structure and document it.