How to Write a Case Study: Questions, Structure, Template

A customer case study that wins business tells one real customer’s story in a simple arc: the problem they had, why they chose you, what you did, and the measurable result. This guide gives you a process for picking the right customer, 25 interview questions that pull out the details prospects care about, a proven page structure, a fill-in template, and the legal basics for using a customer’s name and numbers in the US.

Key Takeaways

Choose customers who look like the buyers you want more of, not just your happiest customer.
A 30 to 45 minute recorded interview gives you better material than any questionnaire.
Lead with the result in the headline, then tell the story in the order problem, choice, solution, result.
Specific numbers and direct quotes carry the whole piece. Vague praise does not persuade anyone.
Get written approval, disclose any incentives, and do not present unusual results as typical.

What a Case Study Is (and Is Not)

A case study is a short, factual story about how one customer solved a specific problem with your product or service. It is longer and more detailed than a testimonial. A testimonial says “they were great.” A case study shows why, with context, steps and results a prospect can compare to their own situation.

It is also not a brochure. The customer is the hero; your business is the guide. When a prospect reads it, they should think “that company had my exact problem,” not “this vendor really likes itself.”

Good case studies do three jobs at once:

Proof: they show that your claims hold up for a real business or person.
Education: they show how the work actually happens, which reduces fear of the unknown.
Sales enablement: your team can send the right story to the right prospect at the right moment, often right after a first call.

Step 1: Pick the Right Customer

Your happiest customer is not always your best case study. Pick the customer whose story will persuade the buyers you want more of. Score candidates against these criteria:

Criterion	Why it matters	Quick test
Looks like your target buyer	Prospects trust stories from peers	Same industry, size or role as the leads you want?
Clear “before” problem	A story needs tension	Can they describe what was going wrong in one sentence?
Measurable result	Numbers make results believable	Do they have data for time, money, volume or error rates?
Enough time has passed	Results need to be real, not projected	Have they used your service for at least three to six months?
Willing to be named	Named stories are far more credible	Will they approve their name, logo and a photo?
Articulate champion	Good quotes need a good speaker	Is there one person who clearly owned the project?

If a customer scores well on four or more, ask them. If they cannot be named for legal or competitive reasons, you can still publish an anonymized version (“a 12-location dental group in Texas”), but it will carry less weight.

Step 2: Ask in a Way That Gets a Yes

Ask at a high point: right after a milestone, a renewal, or a compliment. Make it easy and specific.

“Hi Dana, thanks again for the kind words on last week’s call. Would you be open to a 30-minute interview about how the project went? We’d write it up as a short customer story, you’d review and approve every word before anything is published, and we can include a link to your business. No pressure at all if the timing isn’t right.”

Spell out the time commitment, the approval step and the benefit to them: visibility, a link, a chance to showcase their team. Some businesses offer a thank-you such as a gift card or discount. If you do, be aware that it can count as a material connection that must be disclosed (more on that below).

Step 3: Run the Interview (25 Questions)

Interview by video call and record it with permission, so you can focus on listening. Aim for 30 to 45 minutes. Ask open questions, then follow up with “Can you give me an example?” or “Roughly how much?” Those follow-ups produce the best material.

Background

Tell me about your business and your role.
How big is your team, and who are your customers?
What were your main goals at the time you found us?

The problem

What was going wrong before you started working with us?
How long had that been a problem?
What did it cost you in time, money, stress or missed opportunities?
What had you already tried, and why didn’t it work?
What finally made you decide to fix it now?

The decision

How did you find us?
What other options did you consider?
What concerns did you have before signing up?
What tipped the decision in our favor?

The solution

Walk me through how getting started went.
Who on your team was involved, and what did they do?
Was anything harder than expected? How was it handled?
Which part of our product or service do you use most?
Was there a moment you realized it was working?

The results

What has changed since you started?
Can you put a number on it: hours saved, revenue, cost, speed, errors, customer ratings?
How do you measure that, and over what period?
What has the change allowed you to do that you couldn’t before?
How does your team feel about it now?

Wrap-up

What would you tell a business owner who is on the fence?
If you had to describe us in one sentence to a peer, what would you say?
Is there anything I should have asked but didn’t?

Question 23 almost always produces your best pull quote. Question 25 regularly surfaces a detail nobody planned for.

Step 4: Structure the Story

Most strong case studies follow the same six-part structure. Readers skim, so each part should work on its own.

Headline with the result. “How a Phoenix HVAC Company Cut Missed Calls by Half in 90 Days” beats “Customer Success Story: ABC Heating.”
Summary box. Customer, industry, location, size, the challenge in one line, the solution in one line, and two or three headline results.
The challenge. One to three paragraphs describing the problem in the customer’s words, including what it cost them.
Why they chose you. A short section on alternatives considered and the deciding factor. This handles objections for future buyers.
The solution. What you actually did, step by step, including any bumps along the way. Honesty about a hiccup makes the story more believable.
The results. Numbers first, then the human side: time back, less stress, new opportunities. Close with the customer’s recommendation quote and a single call to action.

Length: 600 to 1,200 words is usually right for a web page. Also create a one-page PDF version for sales and a three-sentence version for proposals and social posts.

Step 5: Write It So Prospects Believe It

Use specific numbers, with context

“Saved a lot of time” persuades nobody. “Cut invoice processing from about 6 hours a week to under 2” does. Always include the timeframe and how the number was measured. If the customer only has estimates, say “roughly” or “about.” Never round up for effect.

Let the customer talk

Use two to four direct quotes, each doing a different job: one about the pain, one about the decision, one about the result, one recommendation. Light editing for grammar and length is normal, but never change the meaning, and send the final quotes for approval.

Show, don’t claim

Replace adjectives with evidence. Instead of “our amazing onboarding,” write “the team was live on day 3; the owner had budgeted two weeks.”

Write for skimmers

Subheads for each section of the structure.
Results in a bold stat line or small table.
Short paragraphs of two to four sentences.
One photo of the real customer or their location, if they agree.

A Fill-in-the-Blanks Case Study Template

Copy this into a document and fill the brackets from your interview notes.

Headline: How [Customer] [achieved result] in [timeframe]

At a glance: [Industry] | [City, State] | [Team size] | Challenge: [one line] | Solution: [one line] | Results: [stat 1], [stat 2], [stat 3]

The challenge: [Customer] is a [description]. By [year], [problem] was costing them [time/money/impact]. “[Pain quote],” says [Name, Title].

Why [Your company]: After looking at [alternatives], the team chose [you] because [deciding factor]. “[Decision quote].”

The solution: [Step 1], [Step 2], [Step 3]. [One honest bump and how it was fixed.]

The results: Within [timeframe], [Customer] [result 1], [result 2] and [result 3]. “[Result quote].”

Recommendation: “[Advice to peers quote].”

Call to action: [One next step, e.g. “Book a 20-minute call to see if we can do the same for you.”]

Worked example (illustrative)

Here is how the template might read for a fictional business. A family-owned plumbing company in Tampa with eight technicians was losing jobs because calls went to voicemail during busy mornings. The owner estimated they missed 15 to 20 calls a week. After comparing an answering service with a scheduling software tool, the company chose the software because customers could book directly online. Setup took four days; the first week produced some double-bookings until the team blocked emergency slots. Three months later, the owner reported that online bookings made up about a third of new jobs and voicemail callbacks had dropped sharply. Every number would be the customer’s own, confirmed in writing before publishing.

Legal and Ethical Basics in the US

A case study is marketing, so the Federal Trade Commission’s rules on endorsements and testimonials apply. Key points from the FTC’s Endorsement Guides Q&A for businesses:

Honest opinions only. The story must reflect the customer’s real experience and views.
Typical results. If the result is exceptional and you cannot show it is what customers generally achieve, make clear what results people can generally expect.
Material connections. If the customer received something of value, such as a discount, free service or payment, for taking part, disclose it clearly.

The FTC’s rule on consumer reviews and testimonials, which took effect on October 21, 2024, also bans fake testimonials, including ones attributed to people who do not exist or who had no real experience with the business. The FTC’s questions-and-answers page on that rule explains what is covered. Never invent a composite customer and present it as real.

Practically: get written approval of the final text, quotes, logo and photos; keep the recording and the approval email on file; and agree on how long you can use the story. Rules change and apply differently by industry (health, finance and legal services have extra restrictions), so check the official guidance or ask an attorney if you are unsure.

Where to Use Your Case Study

Publishing it on a single “Customers” page wastes most of the value. Spread it across the buyer’s path:

Sales follow-up: send the most similar story within 24 hours of a first call.
Service and product pages: add the headline stat and a link next to the relevant offer.
Proposals: include the three-sentence version and the stat line.
Email: feature one story per newsletter, told in 150 words with a link.
Social media: turn each quote and each stat into its own post.
Media pitches: a strong customer story can give a local reporter a concrete angle, with the customer’s permission.

Track which stories sales teams send most and which pages convert, then commission more stories like those.

Frequently Asked Questions

How long should a customer case study be?

For a web page, 600 to 1,200 words usually covers the full story. Keep a one-page PDF and a three-sentence summary as well, so it works in proposals and emails.

What if the customer does not have hard numbers?

Ask for reasonable estimates and label them as estimates. You can also use operational facts they can confirm, such as launch dates, team size or time to set up. Do not make up figures.

Can I write a case study without naming the customer?

Yes. Describe them by industry, size and region instead. It is less persuasive than a named story but still useful, especially in regulated industries.

Should I pay customers to take part?

A small thank-you is common, but it creates a material connection that you should disclose. Many businesses simply offer a link and exposure instead.

How many case studies do I need?

Aim for one per main customer type or service. Three to five well-matched stories usually beat twenty generic ones.

Who should write the case study?

Anyone who can interview well and write clearly. The interviewer should not be the account manager, because customers speak more freely to a neutral person.

Book Your First Interview

Pick one customer from this month who fits your target buyer, send the short request email above, and schedule 30 minutes. Use the 25 questions, fill in the template the same day while the conversation is fresh, and send the draft for approval within a week. One strong, specific story will do more for your sales than a page of generic praise.