Define, scoped.
In context: Stage 05 · Define
Where the chosen, evaluated direction becomes a clear brief and a written specification you can actually build from.
Define turns a validated idea into instructions. You write the brief, fix the specification as must, should and could, set the look and finish, plan the timeline and funding, then map customer needs to engineering characteristics. Get this right and Design has something solid to work from.
What the Define stage is
Define is where a direction stops being a decision and becomes a document. By now you have chosen and evaluated one route. The job here is to write it down precisely enough that someone else could design from it: what the product must do, what it should do, what it could do if budget allows, and what it deliberately will not do. Vague intentions are cheap to hold and expensive to discover later.
For the £149 proofing box, this is the stage where I sat down with Dan and Anna Hartley in Stockport and turned “a box that proves sourdough properly” into a brief. We pinned the requirements: hold 26°C steady, no app, a ceramic body sourced from Stoke-on-Trent, UKCA and BS EN compliance, a build cost between £38 and £55. Each of those is a line someone can check against later.
What’s in this stage
Five activities take Define from a chosen direction to a brief worth designing against. Work them roughly in order.
How it fits the bigger picture
Define is Stage 05. It builds on the direction chosen and tested in Stage 04 Evaluate, and feeds the concept work of Stage 06 Design. A tight brief and a clear specification here mean Design starts from instructions rather than guesses; a loose one means every later stage inherits the ambiguity and pays for it.
What it can do
It converts a chosen direction into a written brief and specification that the design and engineering stages can be held against. Done well, it ends with requirements clear enough that two different people would build roughly the same thing from them.
What it can’t do
It can’t design the product or prove the concept works; that is Stage 06 Design and beyond. And it can’t fix a direction that should never have passed Evaluate. Define sharpens a good decision, it doesn’t rescue a bad one.
See the full 10-stage process →
Try it yourself
Take your own product idea and write three lists in an hour: what it absolutely must do, what it should do, and what it could do if there is room. Then add the one thing it will deliberately not do. That single page is the spine of a real brief.
Or run the guided version. The Free Sprint covers the early stages; the deeper define tools sit in the paid ladder. Start the Free Sprint →
— Start here → Design brief