Equity split
The equity split calculator gives co-founders a starting split from what each brings, set next to an equal split.
Use it before you sign a founders' agreement, to put the reasons for an unequal split into numbers you can argue over.
Each founder is scored on five weighted factors, after Frank Demmler's Founders' Pie, and the weights are judgement you can change.
Built by the IndieHacked team
Close to an equal split
- 54.8% Founder 14.8 points above an equal split of 50%
- 45.2% Founder 24.8 points below an equal split of 50%
Next to published data
- 44.6% of two-founder teams formed in 2025 split equity equallyPublic, Carta, companies formed in 2025
- 51 / 49 median split for two-founder teams, from 57 / 43 in 2021Public, Carta, companies formed in 2025
Vesting, 4 years with a 1-year cliff
A founder who leaves in month 11 keeps nothing. At month 12 a quarter vests, then 1/48 a month.
How the numbers work
The split
Score each founder from 0 to 10 on five factors, and set how much each factor matters. A founder's points are each score times its factor's weight, added up, and their share is their points over the team's. The method is Frank Demmler's Founders' Pie Calculator, published by Carnegie Mellon's Swartz Center for Entrepreneurship, with factors chosen for a software company.
- Points
- sum of (factor weight x founder's score)
- Share
- founder's points / team's points
The weights are judgement
No study gives the right weights. Ours start with time and risk at 30%, the role from here at 25%, expertise and network at 20%, cash and assets at 15%, and the idea and work so far at 10%. They lean on what each founder does from now, because most of a young company's value is still to be built. Move them until they describe your company.
The equal split sits next to the result on purpose. YC's Michael Seibel argued in December 2015 that equal or close to equal splits should become standard. Carta found that 44.6% of two-founder teams formed in 2025 split equally, up from 34.5% in 2016, and that the median split had narrowed to 51 to 49 (June 2026).
Thomas Hellmann and Noam Wasserman found that teams splitting equally were less likely to raise money from outside investors, and that the link does not look causal: it reflects which teams choose an equal split (Management Science, 2017).
Vesting
The chart shows the schedule Michael Seibel describes as typical: 4 years with a 1-year cliff. Nothing vests before month 12, a quarter vests at month 12, then 1/48 of the stake each month until month 48. Carta found that 25% to 35% of two-founder teams formed from 2016 to 2021 had parted ways within five years, so the schedule matters more than the split's last point.
- Share vested
- 0 before month 12, then months / 48, up to 100%
Questions founders ask
How should co-founders split equity?
Start from an equal split and move away from it only for reasons each founder can name. YC's Michael Seibel argued in December 2015 that equal or close to equal splits should become standard, and founders have moved that way: Carta found 44.6% of two-founder teams formed in 2025 split equally, up from 34.5% in 2016.
Is a 50/50 split a mistake?
Not on the evidence. Hellmann and Wasserman (Management Science, 2017) found teams that split equally were less likely to raise outside money, but they read it as a sign of which teams choose equal splits, not as an effect of the split. Carta's median two-founder split for 2025 was 51 to 49.
What is a 4-year vest with a 1-year cliff?
Founders earn their shares over 4 years. Nothing vests in the first 12 months, a quarter vests at month 12, then 1/48 of the stake each month until month 48. A founder who leaves in month 11 keeps none of it.
Why vest founder shares at all?
Because teams split up. Carta found that between 25% and 35% of two-founder teams formed from 2016 to 2021 had parted ways within five years (June 2026). Vesting decides what a founder who leaves takes with them.
Where do the weights come from?
They are the team's judgement, and the page says so. The method follows Frank Demmler's Founders' Pie Calculator: rate how much each factor matters, score each founder on it and split by points. Change the weights until they describe your company.
Should the founder with the idea get more?
The idea carries the lowest default weight here, 10%, because most of the work comes after it. If the idea arrives with code, customers or a patent, score that under work so far and under cash and assets.
Is anything I type into a calculator saved or sent anywhere?
No. A calculator runs in your browser and nothing you enter leaves it. Close the page and the numbers are gone.
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