When Does a Patent Expire? A Complete Guide to Patent Term

How Long Does a Patent Last?

A US utility patent generally lasts 20 years from the earliest effective filing date of the application. This 20-year term was established by the Uruguay Round Agreements Act (URAA) and applies to all utility patents filed on or after June 8, 1995.

For patents filed before June 8, 1995, the term is the longer of 20 years from the filing date or 17 years from the grant date.

What Is the Earliest Effective Filing Date?

The earliest effective filing date is the key date from which the 20-year clock starts. It is determined by looking at the chain of priority claims:

• Non-provisional applications: The filing date of the application itself, unless it claims priority to an earlier application.
• Continuation and divisional applications: The filing date of the earliest parent application in the chain.
• Applications claiming provisional priority: The filing date of the non-provisional application (not the provisional), since provisional applications do not start the 20-year clock.

For example, if a patent was granted from a continuation application filed in 2022, but the original parent was filed in 2018, the 20-year term runs from 2018.

Patent Term Adjustment (PTA)

The USPTO may grant additional days of patent term through Patent Term Adjustment when the office causes delays during prosecution. PTA is calculated under 35 U.S.C. 154(b) and includes:

• A Delay: Failure to act within 14 months of filing
• B Delay: Failure to issue a patent within 3 years of filing
• C Delay: Delays due to interference, secrecy orders, or appeals

PTA can add significant time to a patent's term. For example, if the USPTO took 6 extra months to issue a first office action, the patent could receive 180 days of additional term.

You can check PTA for any patent using the Patent Expiration Calculator.

Terminal Disclaimers

A terminal disclaimer limits a patent's term to match (or be tied to) an earlier-expiring related patent. Patent applicants file terminal disclaimers to overcome obviousness-type double patenting rejections.

When a terminal disclaimer is in effect:

• The patent expires on the same date as the reference patent
• If the reference patent is shorter than the full 20-year term, the disclaimed patent will also be shorter
• The terminal disclaimer creates an enforcement link — if the reference patent becomes unenforceable, so does the disclaimed patent

How to Calculate a Patent Expiration Date

To determine when a specific patent expires:

1. Find the earliest effective filing date by tracing the priority chain
2. Add 20 years to get the base expiration date
3. Add any PTA days granted by the USPTO
4. Check for terminal disclaimers that may cap the term
5. Verify maintenance fee payments — utility patents require maintenance fees at 3.5, 7.5, and 11.5 years after grant, or they expire early

Our free Patent Expiration Calculator automates this entire process. Enter a patent or application number and get the exact expiration date with a full breakdown of each factor.

Design Patents Are Different

Design patents have a different term:

• Filed on or after May 13, 2015: 15 years from the grant date
• Filed before May 13, 2015: 14 years from the grant date

Design patents do not require maintenance fee payments.

Why Patent Expiration Dates Matter

Understanding when a patent expires is critical for:

• Patent owners: Planning licensing strategies, enforcement timelines, and portfolio management
• Competitors: Knowing when technology becomes available for use
• Investors: Evaluating the remaining life of patent assets
• Patent attorneys: Advising clients on prosecution strategy, terminal disclaimers, and continuation filings

Check Your Patent's Expiration Date

Use the Patent Expiration Calculator to instantly calculate when any US utility patent expires. The tool shows the complete calculation with filing date, PTA, and any terminal disclaimer caps.