What matters more than the headline number is the addressable market for your specific business. That's the segment you can realistically reach, given your geography, price point, and compliance status. For example, if you operate in a region with strict device registration, the total US market size is less relevant than the subset of compliant products you're allowed to sell.

Here's where you can put market size to work: use it to gauge whether a category is worth entering, but then drill down to your niche. Look at competitor density, average price points, and regulatory barriers. Those are the numbers that will tell you if there's room for you.

For a practical framework, check out our shop owner's checklist on gauging market size. It walks you through the questions to ask before you commit to a new product line.