Which WordPress pages should carry a calculator?
Put each calculator on the product page for its line: the life insurance calculator on your life page, the HSA comparison on your benefits page, the annuity calculators on your retirement-income page. These pages already attract people researching that product, and a calculator gives them a reason to share their numbers instead of leaving.
If you publish blog posts on coverage questions, a popup button inside the relevant post is a lighter option than a full inline calculator. Browse the calculators by line to match one to each page.