Here is my rough & ready review of Google's Keyword Planner. The Keyword Planner is an excellent, free tool you can use to find out the monthly search volume for relevant keywords.   For more interesting online marketing tool reviews, check out my comprehensive blog post here: 

Blog post:  https://www.cgrundy.com/posts/online-marketing-tools 

Keyword Planner Review blog post:  https://www.cgrundy.com/posts/keyword-planner-review 

Slideshare:  https://www.slideshare.net/ChrisGrundy1/adwords-keyword-planner-find-search-volume-cpc-forecasts 

Youtube Video:  https://www.youtube.com/watch?v=hd1YoF_oEOw&t=1s 

Keyword Planner: https://ads.google.com/home/tools/keyword-planner/