How to Find Out When a Patent Expires
Whether you're a patent attorney managing a portfolio, a competitor watching for market openings, or a manufacturer evaluating licensing risk — here's how to get the answer accurately.
Quick Answer
Enter any patent number into PatentClock's free lookup — it calculates the expiration date instantly, accounting for PTA, PTE, terminal disclaimers, and maintenance fees.
Why Patent Expiration Dates Aren't Obvious
You might think it's simple: filing date + 20 years. For patents filed after June 8, 1995, that's the starting point — but rarely the final answer.
Patent Term Adjustment
Extra days for USPTO prosecution delays
Patent Term Extension
Additional time for FDA regulatory delays
Terminal Disclaimers
Voluntary term shortening to overcome rejections
Maintenance Fees
Non-payment = early expiration (affects ~50% of patents)
Continuation Chains
Term measured from earliest priority date, not filing date
Three Ways to Find a Patent Expiration Date
PatentClock
★ RecommendedEnter any US patent number and get the calculated expiration date in seconds, with a transparent breakdown of every adjustment — PTA, PTE, terminal disclaimers, maintenance fees.
USPTO PAIR / Patent Center
The official source. Search by patent number, navigate through multiple tabs to find PTA, continuity data, maintenance fee records, and transaction history.
Google Patents
Shows an "Anticipated expiration" in the Legal Events section. Quick to check, great for reading patent text and claims.
Step-by-Step: Finding a Patent Expiration Date
Get the patent number
US utility patents are numbered sequentially (e.g., 10,234,567). Design patents start with "D" (e.g., D901,234).
Enter it into PatentClock
Go to the lookup page and type or paste the number. Any format works — with or without commas, prefix, suffix.
Review the expiration breakdown
See the base term (filing date + 20 years), PTA/PTE adjustments, terminal disclaimers, and maintenance fee status.
Check the confidence level
Green = high confidence. Yellow = some data may be incomplete. Red = manual verification recommended.
Add to your watchlist
Get automatic email alerts at 12, 6, 3, and 1 month before expiration. Never miss a deadline.
Special Cases
Design Patents
15-year term from issue date (post May 2015). No maintenance fees required.
Pre-1995 Patents
Longer of: 17 years from issue date OR 20 years from filing date.
Pharma Patents
Can receive up to 5 years PTE for FDA review delays. Check the Orange Book.
Common Mistakes
Ignoring continuity chains
A 2020 continuation of a 2012 app has term measured from 2012.
Assuming maintenance fees are paid
~50% of patents lapse early due to non-payment.
Overlooking terminal disclaimers
Can cut years off by tying term to an earlier patent.
Using Google Patents estimates
Notoriously inaccurate. Never use for legal/business decisions.
Never Miss a Patent Expiration
Free lookups, watchlist alerts, and transparent calculations — start tracking patents today.