When should I file a provisional patent vs. full patent?

Hardware startup, built a novel sensor mechanism. Investors asking about IP protection. Heard about provisional patents being cheaper. When does it make sense to file provisional vs going straight to full patent?

Provisional patent basics:

- Costs: $1,500-5,000 (vs $10,000-20,000 for full utility patent)
- Gives you 12 months to file full patent
- Lets you say "patent pending"
- Establishes priority date (critical for first-to-file system)

Use provisional when: (1) need to disclose invention soon (demo day, publication), (2) want to test market before committing full patent cost, (3) still refining the invention.

filed a provisional 3 years ago. never converted to full patent because we pivoted away from that tech. saved us $15K+. that's the real benefit — it's basically an option to file a patent, not a commitment

honest question: are patents even worth it for startups? I've heard big companies just infringe anyway and dare you to sue them with your $0 budget

Fair point. Patents are worth it when: (1) you're in hardware/biotech where copying is expensive anyway, (2) investors require it (common in deep tech), (3) you're building for acquisition (acquirers pay premium for IP), (4) you're in a space with contingency-fee patent litigators.

For pure software SaaS? Usually not worth it. Trade secrets + speed to market is better strategy.

We're hardware, and sensor is hard to reverse engineer. Sounds like provisional makes sense for us since we have a demo day in 6 weeks. What should the provisional include?

Critical: provisional must fully describe the invention you want to protect. Common mistake is filing a bare-bones provisional then trying to add stuff in the full patent — those additions won't get the early priority date.

Include: detailed technical description, drawings/diagrams, all variations you can think of, how it works, how to make it. You can write it yourself but I'd recommend at least having a patent professional review it.

From the other side: we got acquired last year and our 2 patents added ~$800K to valuation according to the acquirer's IP diligence. For hardware companies pursuing acquisition, patents pay for themselves 10x.