Patent Duration Calculator
Estimate when a US utility or design patent expires based on its filing or grant date.
How this estimate is calculated
Utility patents have a term of 20 years from the earliest effective filing date. Design patents have a term of 15 years from the date of grant. The calculator adds the statutory term to the date you enter.
expiration = start date + term (20 years utility, 15 years design)
What this estimate leaves out
- Patent term adjustment for USPTO delays and patent term extension for regulatory review
- Terminal disclaimers and continuation or priority claims that change the effective filing date
- Maintenance fees, which must be paid at intervals to keep a utility patent enforceable
For an authoritative date, use the USPTO patent term calculator and the patent own front page and fee record.
Questions We Get Asked
How long does a US patent last?
A utility patent generally lasts 20 years from the earliest effective filing date, and a design patent lasts 15 years from grant. Maintenance fees and term adjustments can affect the exact end date.
Do I have to pay to keep a patent?
Utility patents require maintenance fees at roughly 3.5, 7.5, and 11.5 years after grant. Missing a fee can cause the patent to expire.
Can a patent term be extended?
Yes. Patent term adjustment compensates for certain USPTO delays, and patent term extension can add time for regulatory review of certain products.
When does the 20-year clock start?
It runs from the earliest effective filing date, which may be the filing date of a parent application in a priority chain, not necessarily the issue date.
Important: This page is published for general research and education. It is not legal advice, and it does not create an attorney-client relationship. Statutes are amended often and may contain exceptions. Because outcomes depend on your own facts, speak with a licensed attorney in your jurisdiction about your situation. See the full disclaimer.