The number of products per product managers varies wildly between (and within) companies. One or two products generally seems more rational than the 10-20 that I hear for some companies. That said, here's how you find out. How many hours per week do you want a product manager focused on each activity on the Pragmatic Marketing Framework for each product?

Add it up.

Do that for all products and you'll know how many hours have been allocated.

An effective alternative is the portfolio strategy: put the products together into a family and manage them as one. Perhaps one product manager deals with development for all products while another works with sales and marketing for all of  them.  Does that work in your environment?

My Product Management Triad article may help.

Answered by Steve Johnson

There's another angle here. Think about the target market segments for each product. For instance, if a new product is coming that's going to replace two existing products, presumably the target market segment is the same, so it makes sense to group these 3 together -- and then manage them either with 1 person or a triad, depending on the time you want spent there. It's also helpful to think of product management staff by the products' revenue potential. I might have one person on staff who manages 7 or 8 products -- probably including legacy products, or 2 generations of solutions, or low revenue potential, or all serving the same group of people (or segments with a big overlap).

It's like affinity mapping for staffing -- look at all your products, and group them by the segments they serve. Consider revenue potential (this is easier if you keep an up to date business plan), and actual revenue.

Balance workload using revenue and revenue potential as a guide, and consider your general desires (which products should get the most attention, and can some be basically ignored because chances are all products are not equal). Finally, assign products according to skill sets among the team -- this is where you consider technology depth, market knowledge, and workload. By this point, you should begin to see a picture of your organizational strategy -- perhaps part of the product set will get managed in a triad, while others will be managed by individuals.

Once you have good product assignments, it's fairly easy to make adjustments by sliding one product to another owner, without disrupting the entire team.

You can set responsibilities, then tweak as you go -- if product managers are overloaded you can use the Framework to show that, and to help get justification for hiring. When you hire a new manager, you can have them dig into the strategic activites on the left-side of the Framework. When they have a good level of market knowledge, THEN have them take responsibility for the product. That way, every time you hire you increase the market-driven nature of your team.