You ran the customer interviews. Now you have pages of notes and quotes. The gap most founders fall into is between "I learned a lot" and "here is what to build." Here is how to bridge it.
The short answer
Turn interviews into requirements by finding the patterns across conversations, translating feature requests back into underlying needs, prioritizing by how painful and common each need is, then writing each as a clear requirement tied to a real user need. Solve problems, not literal requests.
Step 1: Find the patterns
Read across all your interviews and tag recurring themes: the same pain, the same workaround, the same wish, showing up again and again. A problem mentioned once is noise; one mentioned by most of your interviewees is signal. Those repeated patterns are your real requirements source.
Step 2: Translate requests into needs
Customers will ask for specific features ("I want a button that..."). Do not take these literally. Ask what need is behind the request. Often several different feature requests point to the same underlying need, which you can solve more simply than building each request. Build for the need.
Step 3: Prioritize ruthlessly
Rank needs by two things: how painful and how frequent. The needs that are both severe and common are your must-haves. Everything else is later. This is what keeps your first version small (see what belongs in your MVP).
Step 4: Write clear requirements
For each prioritized need, write what the product must do, plainly and specifically, tied back to the user need it serves. A builder should be able to read it without guessing. This is the backbone of a product requirements document.
From requirements to a running product
Requirements on paper are still just intent, and intent gets misread once building starts. The most reliable way to carry requirements into a build is to make them executable. A product simulation does that: it turns your prioritized requirements into a documented, runnable foundation, so what you learned from customers becomes a working product, not a document that drifts.
Got your requirements? Make them real. Start a project.
Frequently asked
How do I avoid building every feature customers ask for?
Customers describe problems and request features; your job is to translate requests back into the underlying need, then solve the need in the simplest way. Build for the problem, not the literal feature list.
How detailed should requirements be?
Detailed enough that a builder would not have to guess. Each requirement should tie to a real user need from your interviews and describe what the product must do, not just a vague capability.