You can set minimum and maximum CPM rates for both Classic Canvas and Journey Canvas campaigns. Like many settings, you can configure these fields at the canvas level, which means the same rates would apply to all creatives, tactics, steps, and paths. If you'd rather not blanket the entire canvas with the same rates, set custom rates at the campaign (Classic Canvas) or path (Journey Canvas) levels.
If you're building a new campaign or path on Classic Canvas or Journey Canvas, the workflow naturally guides you to the CPM form. Optionally, you can open an existing campaign or path and edit the form fields.
So the question is, what's the best CPM range for a campaign? The answer depends on your aims and priorities. I know that's a wishy-washy response, so let me describe some options that provide direction rather than certainty. Note that the fields mentioned below are only visible if you're running dCPM and you're not taking a margin.
Here are some suggestions that can help you formulate your thinking. These figures are discussion starting points and are not intended to represent best practices for all clients in all situations.
Here's a rule of thumb. Think about the different channels you want to access with the campaign and ask yourself, "What's the highest CPM you expect to pay among those channels?"
That's the number you should enter in the Max field. If you're buying CTV inventory, for instance, that CPM could easily be in the $20-50 range. Remember, you can override these settings at the campaign and path levels when you build the campaign. That means, for instance, you could set a native display CPM to $8 and enter a $25 CPM for CTV. FYI, you can also override these values through bid optimization.