Cofounder compatibility test: what it should measure, a free version to run together, and its limits

A cofounder compatibility test is a structured way for two people to compare how they work and what they want, before they commit to building a company together. Each person answers the same questions on their own, then you put the answers side by side and look at where they differ.

It sounds formal for something that often starts with a good coffee. But the alternative is relying on impressions, and impressions are shaped by how much you like someone. A test makes you both say specific things, such as "20 hours a week until June" or "I'd be happy with a profitable company of 15 people", that are easy to compare and hard to misremember later.

This guide covers what a compatibility test should measure, a free version you and a potential cofounder can run together, how to score it, what a mismatch means for each dimension, and the limits of any test. If you're still working out what you want in a cofounder in the first place, start with our guide on what to look for in a cofounder.

What a cofounder compatibility test should measure

Compatibility doesn't mean being alike. On some dimensions you want to be close; on others, different is better. A useful test measures seven things and treats them differently.

The pattern matters more than any single score. Two people can differ on most personality items and work very well together. Two people who differ by 25 hours a week on commitment are likely to struggle, however much they like each other.

Why test compatibility at all?

Most early conversations between potential cofounders cover the idea and each other's background. They rarely cover how many months each person can go without pay, what each would consider a good outcome, or how each reacts when a deadline slips. Those are the topics where differences cause trouble later, and they're awkward to raise without a reason.

A test gives you the reason. "Let's both fill this in and compare" is easier to say than "I'm worried you won't work as hard as me." It also helps each person answer honestly, because you write your answer before you know the other person's.

Gloria Lin, describing the process she used to find her cofounder, made the same point about her questionnaire: "It's important to do it independently as opposed to running through them together live" (First Round Review).

How to run the test together

1. Agree to do it. Suggest it after one or two good calls, before any trial project starts. Frame it as something you both do, not a screen one person runs on the other. 2. Answer separately, in writing. Give yourselves a few days. Each of you fills in the questions below in your own copy, without discussing them. 3. Swap at the same time. Send your answers to each other at an agreed hour, so neither person can adjust after seeing the other's. 4. Mark the gaps. Each of you goes through both sets and marks every item using the scoring rules further down. 5. Talk through the gaps, not the matches. Lin and each candidate covered a section or two per sitting, with "about three to five sessions total". Two or three shorter sessions work for this test. 6. Turn what's left into a trial question. Anything you can't settle in conversation becomes something to watch during a cofounder trial project.

Answer as you are now, not as you'd like to be. If a question doesn't apply yet, say so rather than guessing.

The test: questions for each dimension

The test uses three kinds of question. Numbers (hours, months, dates) are compared directly. Ratings use a 1 to 5 scale, where 1 means "not like me at all" and 5 means "very like me". Choices ask you to pick one option from a list. Write one sentence next to any answer that needs context.

These are different from interview questions. For questions to ask each other out loud, with what to listen for, see our questions to ask a potential cofounder.

1. Commitment

• Number: Hours a week I can give this now.
• Number: Hours a week I can give this in six months.
• Number: Months I can live without a salary from this company.
• Choice: What has to happen before I work on this full-time? (a) nothing, I already am (b) a specific date (c) a milestone, such as paying customers or outside money (d) I don't know yet.
• Rating: If this hasn't worked after a year, I'd still want to keep going.
• Rating: I'm also seriously considering other projects or job offers.

What a mismatch means. A gap of more than about 10 hours a week, or more than six months in runway, is worth a direct conversation. It doesn't have to end things if one person's hours rise on a known date. It usually does if one answer is "full-time now" and the other is "I don't know yet".

2. Working style

• Rating: I like a detailed plan before starting.
• Rating: I prefer to talk things through on a call rather than in writing.
• Rating: I need regular time alone, without messages, to do my best work.
• Choice: My most productive hours are (a) early morning (b) daytime (c) evening (d) late night (e) it varies.
• Choice: I'd like us to work in the same room (a) every day (b) a few days a week (c) a few days a month (d) rarely.
• Rating: I'm comfortable shipping work that's good enough and improving it later.
• Number: Hours I expect a reply to a work message to take, on a normal weekday.

What a mismatch means. Most working style gaps are workable once you name them. Write a rule for each gap of 3 or more, such as "decisions go in writing" or "overlap from 2 to 5 every weekday". Gaps on in-person time and reply speed are the ones that keep causing friction, so test those during the trial.

3. Ambition

• Choice: In five years, I'd like this company to be (a) a profitable business that pays us well (b) a company of 50 or more people growing fast (c) as large as it can possibly get (d) sold to a larger company (e) I'm open.
• Rating: I'd want to raise outside money if it helped us grow faster.
• Rating: I'd be happy if this became a solid, profitable company that never grew very large.
• Rating: I'd accept several years of high risk for a small chance of a very large outcome.
• Write one sentence: The outcome I'd regret.

What a mismatch means. Different answers to the five-year question are a reason to stop and talk before anything else. Ambition shapes almost every later decision: how fast to hire, whether to take outside money, how much risk to accept, when to sell. A gap here tends to resurface in each of them. If you can't describe a company you'd both be glad to have built, the rest of the test matters less.

4. Personality

These items cover broad areas that personality research commonly measures: how open you are to new ideas, how organised you are, where you get energy, how you handle disagreement and how you react to stress.

• Rating: I get restless doing the same kind of work for long.
• Rating: I keep careful track of details and deadlines.
• Rating: I get energy from meeting new people, such as customers and investors.
• Rating: I'd rather keep the peace than push a point I'm fairly sure of.
• Rating: When things go wrong, I stay calm on the outside and on the inside.
• Rating: I tell people directly when I think their work isn't good enough.

What a mismatch means. Personality differences are often useful. A founder who loves meeting people and one who loves detail cover more ground than two of either. What causes trouble is not knowing the difference: one person reads directness as rudeness, or quiet as agreement. Talk through each gap of 3 or more and agree what it means in practice. If you want a more formal measure, the International Personality Item Pool publishes personality items and scales, including measures of the five major personality factors, in the public domain (IPIP).

5. Goals

• Write one sentence: Why I want to start a company now, rather than in three years.
• Choice: In three years I expect to live in (a) the same city (b) a different city I already know (c) somewhere not yet decided.
• Rating: Big changes in my personal life are likely in the next two years (a move, a new child, caring for someone).
• Rating: The people closest to me know about this plan and support it.
• Number: The minimum monthly income I'd need once savings run out.

What a mismatch means. Goals sit outside the company but decide what each person can give to it. A planned move or a new baby isn't a problem in itself. Keeping it quiet is. Gaps here should be discussed openly and early, and anything that changes the commitment numbers should be written next to them.

6. Values

Values are hard to rate in the abstract, so this section uses short scenarios. Pick what you'd most likely do.

• Scenario: A customer offers to pay a year in advance if you promise a feature you aren't sure you can build. (a) Take it and try (b) Take it, and tell them honestly it may not happen (c) Decline until you know.
• Scenario: A supplier undercharges you by a large amount. (a) Say nothing (b) Tell them (c) Depends on the relationship.
• Scenario: A close friend asks for a job you don't think they're right for. (a) Hire them (b) Say no and explain why (c) Offer something smaller.
• Scenario: A competitor's former employee offers to share their old employer's customer list. (a) Accept (b) Decline (c) Ask a lawyer first.
• Rating: I'd turn down a large customer if their business made me uncomfortable.
• Write one sentence: Something I won't compromise on in how this company is run.

What a mismatch means. Values gaps are the most serious kind, because they show up in decisions made when the other person isn't there. You can't check every call your cofounder makes, so you have to trust the reasoning behind them. A different answer on a scenario isn't automatically a dealbreaker. A different reason often is.

7. Skills and interests

• List: The three things I'm best at that this company needs.
• List: The parts of the work I want to avoid.
• Choice: Which areas would I want to lead? (a) product (b) engineering (c) design (d) sales and marketing (e) operations (f) fundraising and finance.
• List: The industries or problems I'd happily work on for five years.
• Rating: I'd be fine if the idea changed completely, as long as we kept working together.

What a mismatch means. Here you want difference in skills and overlap in interests. Two people who both want to lead product and neither wants to sell will end up with one of them doing a job they didn't choose. Two people with no interest in common will struggle to pick the next idea if the first one fails.

How to score and compare your answers

Go through every item and mark it one of three ways.

For choices and scenarios, mark "aligned" if you picked the same option, and "talk" otherwise. For written answers, read them aloud to each other and mark them together.

Then weigh the marks by dimension. A "test" on commitment, ambition, goals or values counts for much more than a "test" on personality or working style. Many pairs end up with a long list of personality differences and a short list of serious gaps, which is a good result. Decide which dimensions are your must-haves before you swap answers, and keep the list short (our guide on what to look for in a cofounder explains how to pick them).

A worked example

This example is made up to show how the scoring works. Two people, Ana and Sam, are thinking of building scheduling software for small clinics.

• Commitment. Ana: 35 hours now, 45 in six months, 12 months of runway. Sam: 15 hours now, 40 in six months once his contract ends in April, 8 months of runway. Marked "talk": the gap closes on a known date.
• Ambition. Both chose (b), a company of 50 or more growing fast. Aligned.
• Working style. Ana rated "detailed plan first" at 5; Sam at 2. Marked "test". They agreed a one-page plan per week and to watch whether it felt like too much or too little.
• Personality. Five gaps of 2 or more, mostly on energy from meeting people. They agreed Sam would lead customer calls.
• Values. Both picked (b) on the advance-payment scenario. On the friend's job, Ana chose (c), Sam chose (b). Marked "talk"; their reasons turned out close.
• Skills. Ana wants to lead product and engineering; Sam wants sales and operations. Different skills, the same interest in healthcare. Aligned.

Result: no serious gaps, one commitment gap with a date on it, and one working-style question to test in a four-week trial. That's a good reason to start the trial, not a reason to skip it.

What a mismatch means, and what to do next

A gap is information, not a verdict. After you've marked everything, each gap falls into one of four groups:

• Fine as it is. Different skills, most personality differences. Name them and move on.
• Fixable with a rule. Most working-style gaps. Agree a rule, write it down, and check after a month whether it works.
• Fixable with time. Commitment gaps with a date attached. Write the date down and check it when it arrives.
• Hard to fix. Large gaps in ambition, goals or values, or commitment with no date. These rarely close through conversation. It's kinder to both of you to say so now.

If the test shows one hard gap, talk about it before doing anything else. If it shows two or more, most pairs are better off staying in touch as friends and looking for someone who fits.

The limits of any compatibility test

A test is a useful start. It isn't a prediction, and it helps to be clear about why.

People describe who they'd like to be. Asked how they work, most people answer with their best week. Research on predicting behaviour finds that past behaviour is a strong guide to future behaviour when situations are familiar, while intentions matter more in new ones (Ouellette and Wood, 1998). Starting a company is new for most people, so stated intentions matter, but they still need checking against what each of you actually does.

Both people want it to work. Two people who like each other and like the idea tend to nudge their answers closer. Answering separately helps. It doesn't remove the pull.

It measures fit, not quality. Two people can be very compatible and both be unreliable. A test shows whether you'd work well together, not whether either of you will do the work.

Answers change. Runway shrinks, jobs change, families grow. A test from March may not describe September. Run it again after a few months, or whenever something big changes for either of you.

It only covers what it asks. No questionnaire covers everything. If something matters to you and isn't on the list, add it.

A score can't see the future. Be wary of any quiz that promises one number will tell you whether a partnership will work. A score summarises what two people said on one day.

Why a trial project still matters

A test tells you what each of you says. A trial project shows what each of you does. Lin compared answers over several sessions and still spent four months working with the person she chose before committing. Steve Blank's advice is to "date first": an intense stretch of work together, then "a provisional 30-day working period" (First Round Review).

Use the test to choose the trial's question. If working style came out as "test", design a project where you have to plan together. If commitment had a gap with a date on it, set the trial to run past that date. Our guide to running a cofounder trial project has a brief template and a four-week plan.

What to look for in an online cofounder compatibility quiz

If you'd rather use an online quiz than the version above, a few checks help you judge it:

• Do both people answer? A quiz one person takes alone describes that person. Compatibility needs two sets of answers.
• Are answers private until both are done? Otherwise the second person's answers bend towards the first.
• Does it cover commitment, ambition, goals and values? A personality quiz alone misses the dimensions that cause most trouble.
• Does it show item-by-item differences? A single score hides the one gap that matters.
• Does it say what it can't do? A good tool treats its result as a starting point for a conversation.

How Foundinity measures compatibility

Foundinity runs this comparison before you meet anyone, across everyone who fits what you need.

You state what you need in a cofounder, and answer an assessment about how you work: commitment, working style, ambition, personality, goals, values, alongside your skills and interests. A multi-trait algorithm built on established psychological compatibility models ranks the people you see by compatibility on multiple dimensions around who you are and how you work. Every match then shows a compatibility breakdown of where the two of you align and where you differ.

• The breakdown is your trial's starting point. Bring the differences to your first call and design the trial around them.
• A 10-day clock on each match keeps things moving, and you book the intro call in the app.
• Your profile isn't public. Only compatible members can see it, and an "exploring" status lets you look at your own pace.
• Pricing: free to get started; Plus is $5 a week or $15 a month. See how it works.

FAQ

What is a cofounder compatibility test?

A set of questions two potential cofounders answer separately and then compare, covering commitment, working style, ambition, personality, goals, values, and skills and interests. It shows where you align, where you differ and which differences need a conversation or a trial.

How do you test cofounder compatibility?

Answer the same questions separately and in writing, swap answers at the same time, mark each item as aligned, talk or test, and discuss the gaps over two or three sessions. Then run a short trial project focused on whatever you couldn't settle in conversation.

How do I know if my cofounder is compatible?

Look for close answers on commitment, ambition, goals and values, different but complementary skills, and personality differences you both understand. Then check that what each of you said matches what you do in a few weeks of real work.

Is there a free cofounder compatibility test?

Yes. The questions on this page are free to copy and use. Each of you fills them in separately, then you compare answers using the scoring table above.

What questions are on a cofounder compatibility test?

Numbers (hours a week now and in six months, months of runway, minimum income), ratings on working style and personality, choices about the company you want to build, and short scenarios that show your values in practice.

Can a personality test tell you if you'll be good cofounders?

On its own, no. Personality is one dimension of seven, and differences there are often useful. Gaps in commitment, ambition, goals and values cause more trouble, and a personality test doesn't measure them.

Should cofounders have similar personalities?

Not necessarily. Different personalities often cover more ground, for example one person who enjoys meeting customers and one who enjoys detail. What matters is that you both know the differences and agree how to handle them.

What if our compatibility test shows big differences?

Sort them into fine as they are, fixable with a rule, fixable with time, and hard to fix. One hard gap is worth a frank conversation before anything else. Two or more usually means looking for someone else.

How long does a cofounder compatibility test take?

About 30 to 45 minutes each to answer, then two or three conversations of an hour to go through the gaps.

When should you take a compatibility test with a potential cofounder?

After one or two good calls and before a trial project. Run it again after a few months, or whenever something big changes for either of you.

Is a compatibility test enough to choose a cofounder?

No. It tells you what to talk about and what to test. You still need a few weeks of real work together and conversations with people who've worked with each of you.

Sources

• Gloria Lin, "The Founder Dating Playbook", First Round Review, 30 September 2019, checked 12 November 2026.
• First Round Review, "Looking for Love in All the Wrong Places: How to Find a Co-Founder", interview with Steve Blank, 26 January 2015, checked 12 November 2026.
• Judith A. Ouellette and Wendy Wood, "Habit and Intention in Everyday Life: The Multiple Processes by Which Past Behavior Predicts Future Behavior", Psychological Bulletin 124(1), 54 to 74, 1998; checked 12 November 2026.
• International Personality Item Pool, checked 12 November 2026.
• Foundinity features and pricing from foundinity.com, checked 12 November 2026.