How to Write a Case Study for Your Small Business

A case study is a short, true account of one client's problem, the work you did and what changed, told with the client's permission. To write one, pick a client whose situation matches the buyers you want, interview them, write it up in a fixed order, check every number with them and get their written approval before you publish.

This page is about the full story. For short quotes and star ratings, see how to collect customer testimonials. For where case studies fit in your wider content, see content marketing for small business.

Pick the right client story

Choose a client who:

• looks like the buyers you want more of, in size, industry or problem;
• had a clear problem before you started;
• can describe a result in their own words, with numbers if they have them;
• is willing to be named, or to be described clearly if they'd rather stay anonymous.

Ask before you start writing. Some clients can't be named because of their own contracts or policies.

Interview the client

A 20 to 30 minute call is enough. Ask open questions and let them talk:

• What was going wrong before we started?
• What had you already tried?
• What made you decide to work with us?
• What changed after the work, and how do you know?
• What would you tell someone in your position?

Record the call with permission, or take notes and read the key quotes back to them.

Write it in a fixed order

Use the same structure every time so readers know where to look:

1. Headline: the client type and the result, in plain words.
2. The problem: what was going wrong, in the client's words where you can.
3. The work: what you did, in order, without jargon.
4. The result: what changed, with numbers the client has confirmed.
5. A quote: one or two sentences from the client.
6. Next step: how a reader can get in touch.

Aim for one or two pages. A reader should get the point from the headline and the first paragraph.

Check every number and get written approval

Only publish numbers the client has seen and agreed to. If they can't share exact figures, describe the change without them, such as "cut the time to send invoices from days to the same afternoon", rather than guessing. Send the final draft for written approval, and keep that approval with your records.

Disclose anything you gave in return

In the US, a client's account of your work can count as a testimonial. The FTC's questions and answers on its Consumer Reviews and Testimonials Rule (checked October 31, 2026) say: "A testimonial, one type of endorsement, is an advertising message that consumers are likely to believe reflects the opinions, beliefs, or experiences of a consumer or celebrity who has purchased, used, or otherwise had experience with a product, service, or business." If you gave the client a discount, a month at no charge or anything else for taking part, the FTC's guidance on its Endorsement Guides (checked October 31, 2026) says: "Even an incentive with no financial value might affect the weight or credibility of an endorsement and would need to be disclosed." Say what they received in the case study, and ask a lawyer if you're unsure.

Worked example: turning a result into a number

Sample figures, confirmed with the client before publishing: before the project, a client's office manager spent 6 hours a week preparing invoices; afterward it took 2 hours. That's 6 minus 2 = 4 hours saved a week, and over 48 working weeks, 4 × 48 = 192 hours a year. In the case study, show both the weekly and the yearly figure, and say they come from the client's own records.

Use it more than once

One approved case study can become a page on your website, a one-page PDF to send with proposals, a short section in a sales email and a slide in a pitch. Link to it from the services it describes.

Mistakes to avoid

• Publishing before the client has approved the final text.
• Rounding up results or adding numbers the client didn't give.
• Writing about yourself instead of the client's problem.
• Leaving out a discount or other incentive the client received.

When this guide isn't for you

If your clients work under strict confidentiality, such as in legal or health services, check what you're allowed to publish before you ask. This page doesn't give legal advice; ask a lawyer about permissions and disclosures.

Related Articles

• How to Collect Customer Testimonials
• Content Marketing for Small Business
• How to Get Referrals for Your Business

Frequently Asked Questions

How long should a small business case study be?

A page or two. Readers should be able to get the result from the headline and the first paragraph.

What if the client won't share exact numbers?

Describe the change in words they're comfortable with, and don't estimate figures for them.

Do I need the client's permission to publish a case study?

Yes. Get written approval of the final text, and keep it with your records.

Do I have to disclose a discount I gave for a case study?

In the US, the FTC's Endorsement Guides guidance (checked October 31, 2026) says: "Even an incentive with no financial value might affect the weight or credibility of an endorsement and would need to be disclosed." Ask a lawyer how it applies to you.