How to use the founder equity split calculator
- Set the four weights: idea, time, cash and skills. A higher weight means that kind of contribution counts for more. The starting values are examples to change.
- Add a row for each founder and give a score for each kind of contribution. Any scale works, such as 0 to 10, as long as you use the same scale for everyone.
- In More options, enter an option pool percent if you want to set some ownership aside, and a total number of shares if you want the split as shares.
- Read the headline for the largest share, then the table for each founder's weighted points, ownership percent and shares.
Formula
points = idea x w1 + time x w2 + cash x w3 + skills x w4
ownership = points / total points x (100% - pool)
shares = total shares x ownership
Percents are rounded to hundredths with the leftover hundredths given to the largest remainders, so they always add up to exactly 100.00%. Shares are divided the same way, so every share belongs to someone.
Three founders with the example weights
With weights of 1 for idea, 2 for time, 1 for cash and 1 for skills, Ana scores 8, 9, 5 and 7, which is 8 + 18 + 5 + 7 = 38 points. Ben scores 4, 7, 10 and 6, which is 4 + 14 + 10 + 6 = 34 points. Cy scores 3, 5, 2 and 8, which is 3 + 10 + 2 + 8 = 23 points. The total is 95, so Ana holds 38 / 95 = 40.00%, Ben 34 / 95 = 35.79% and Cy 23 / 95 = 24.21%.
Setting aside a 10% option pool leaves 90% for the founders, which becomes 36.00%, 32.21% and 21.79%, with the pool at 10.00%. Over 1,000,000 shares that is 360,000, 322,100, 217,900 and 100,000. If two founders have 60 and 40 points in a single factor, the split is simply 60.00% and 40.00%.
What the weights are for
Founders often disagree about whose contribution matters most: the person with the idea, the one working full time, the one who put in money, or the one with the rare skill. Weights make that argument concrete. If time matters twice as much as cash to your group, give time a weight of 2 and cash a weight of 1, and the arithmetic follows from what you decided.
The calculator does not tell you which weights are fair. It shows what your weights produce, so you can change one number and watch the split move. Try the extremes, such as giving all the weight to time, to see how sensitive the result is. Settling the weights together, before anyone scores themselves, usually avoids the awkward part.
A formula is a starting point
Contributions are hard to compare and they change. Someone who works full time for a year will contribute more than the same person working weekends, and a score given today cannot know that. Many founders therefore agree on vesting, where shares are earned over time, and review the split when roles change. This tool does not model vesting, taxes, or the legal agreement that records who owns what. A lawyer can set that up properly.
If the company will raise money later, the split you choose now will be diluted. The Equity Dilution Calculator shows how a priced round changes each holder, and the Equity Compensation Calculator covers shares and options given to employees.
Rounding and shares
Dividing 100% among three equal founders gives 33.333 percent each, which cannot be written exactly with two decimals. The page gives the extra hundredth to the earliest of the tied founders so the total is exactly 100.00%: 33.34%, 33.33% and 33.33%. Shares are handled the same way, so the share counts always add up to the total you entered, with the pool counted as one more holder.
Assumptions and limits
- Scores and weights are zero or more, with at most three decimals. At least one weighted point must exist in total.
- The option pool is a percent of the whole company, from 0 up to but not including 100, with at most two decimals.
- Total shares, if entered, must be a whole number of 1 or more. It includes the shares of the pool.
- Nothing is stored or uploaded. Vesting, taxes and legal terms are not modeled, and the result is not legal or financial advice.
Frequently asked questions
How do I split equity between co-founders?
Agree on what matters to your group, such as idea, time, cash and skills, give each a weight, and score each founder. The calculator turns the weighted points into percentages. It shows the arithmetic of your choices and does not decide what is fair.
Is an equal split a good idea?
Some founders choose equal shares because they expect equal effort, and others prefer a split that reflects different roles. Setting every score the same in this calculator gives an equal split, so you can compare it with a weighted one before you decide.
What is an option pool?
It is a share of the company set aside for future employees or advisors. Entering a percent here reserves it first, and the founders share the rest in proportion to their points.
Why do the percents add to exactly 100?
The page divides the percentage points in whole hundredths and gives any leftover hundredths to the largest remainders. That keeps the total exact, so a three way tie shows 33.34%, 33.33% and 33.33% instead of 99.99%.