How do I check if my invention is patentable before spending money?

Start with a free self-search on the USPTO's Patent Public Search tool, Google Patents, or Espacenet to see if anything close to your idea is already patented. It won't be comprehensive, but it catches obvious blockers before you spend anything. If nothing obvious turns up, a paid automated or "knockout" search ($100–$500) adds broader database coverage.

For a filing decision you're actually committing money to, a professional prior art search with a written patentability opinion ($1,000–$4,000, depending on complexity) is worth it, an attorney or search firm evaluates what you find against the legal bar for novelty and non-obviousness (35 U.S.C. §§ 102–103), which a keyword search alone can't tell you.

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