Co-Founder Equity Split Calculator
Splitting equity is one of the hardest early conversations. Score each founder on the factors that actually build the company and get a fair, defensible starting point for the discussion.
Suggested split
A starting point for the conversation — not legal advice. Vest equity over 4 years with a 1-year cliff, and put the final split in writing with a lawyer.
How the equity split is calculated
Each founder is scored 0–10 on five contribution factors — idea & IP, capital invested, time & commitment, risk taken, and skills & execution. We total each founder's scores and convert them to a percentage of the whole. It's the same weighted-contribution approach behind popular equity calculators, made adjustable so you can weigh the factors your team cares about most.
Should co-founders split equity 50/50?
Equal splits are common and often the right call when both founders join at the same time with comparable commitment — it signals trust and avoids resentment. But an equal split isn't automatically fair: a founder who brings the idea, works full-time, and puts in capital is contributing more than one joining later part-time. Use this calculator to make those differences explicit, then decide together.
Protect the split with vesting
Whatever you agree, put it on a 4-year vesting schedule with a 1-year cliff so equity is earned over time, not handed over on day one — it protects everyone if a co-founder leaves early. This tool is a starting point, not legal advice; finalize the split with a lawyer. When you're ready to launch, plan spend with our runway calculator and list your startup on Launchory. Building tools for teams? Explore HR & hiring and SaaS startups already listed.
Frequently asked questions
Exactly how is the suggested split calculated?
Each founder is scored 0–10 on five factors — idea & IP, capital invested, time & commitment, risk taken, and skills & execution — for a maximum of 50 points each. Every founder's five scores are summed, then each founder's total is divided by the sum of everyone's totals to get a percentage. Two founders who both score 40/50 get an even 50/50 split; a founder who scores 30/50 against a co-founder's 40/50 gets 30/70 ≈ 42.9%, not 50%.
What does a 50/50 split actually cost you if one founder leaves at month 9?
It depends entirely on whether the equity was subject to vesting — and this is the single biggest gap founders leave open. With no vesting, a founder who leaves at month 9 keeps their full 50% forever, for roughly 9 of the 48 months (18.75%) of the commitment implied by a standard 4-year schedule. With the standard 4-year vesting and 1-year cliff we recommend below, month 9 is before the 12-month cliff, so 0% has vested — the departing founder keeps none of the equity, and it returns to the company (or the cap table pool) instead of sitting with someone no longer working on it. That gap, 50% vs 0%, is the entire reason vesting exists.
Are the five factors weighted, or does each count equally?
Each of the five factors is scored on the same 0–10 scale and summed unweighted, so idea & IP counts for as much of the total as skills & execution by default. If your team thinks execution should count for more than the original idea, the practical way to express that with this tool is to be more generous with execution scores and stricter with idea scores — the calculator does not currently apply separate multipliers per factor.
What happens if I score every founder identically?
You get an exactly even split. If two founders both score, say, 8 on every factor, their totals are identical and each gets exactly 50.0%; with three founders all scored identically, each gets 33.3%. The calculator does not nudge toward round numbers — it reports the precise arithmetic result of the scores you enter, decimals included.
How many founders can I model, and is there a minimum?
Between 2 and 5. The tool starts with two founder cards, lets you add up to five, and will not let you remove a founder below two — a "split" needs at least two people to mean anything, and beyond five the scoring conversation usually needs a spreadsheet and a lawyer more than a calculator.
Does this calculator save my scores or send them anywhere?
No — it runs entirely in your browser with no persistence at all. There is no save button, no local storage and no server call, so refreshing or closing the tab clears everything you entered. Screenshot or write down the percentages before you navigate away if you want to keep them.
Is a calculator-suggested split legally binding?
No, and it is not meant to be. This is a structured starting point for a conversation founders often avoid having explicitly — it has no legal force until it is written into your cap table and formation documents by a lawyer. Treat the output as the opening number for a discussion, not the final word.
How does vesting actually protect the split once you agree on it?
A standard structure is 4-year vesting with a 1-year cliff: nothing vests before month 12, then roughly 1/48th of the total vests each month after that (or 1/4 per year on a coarser schedule) until the full amount vests at month 48. It protects everyone from the same failure mode — a founder who agrees to 50% and leaves after a few months walking away with equity equal to a founder who stays and builds the company for years. Put whatever split this tool suggests on a vesting schedule before you treat it as final.
How does this compare to Slicing Pie, Eqvista or other equity-split tools?
Slicing Pie tracks ongoing contributions (time, cash, ideas) dynamically and reslices equity as the company grows, which suits pre-revenue teams still figuring out who is doing what. Eqvista and similar cap-table platforms are built for managing and issuing equity once a split is decided, not for deciding it. This calculator sits earlier in that pipeline: a free, one-time, no-account tool for the specific "what is a fair starting percentage" conversation, before you move to a cap-table tool or a lawyer to formalize it.