Interactive Tool
Patent Term Calculator
Calculate the expiration date of a U.S. utility patent, accounting for Patent Term Adjustments (PTA), Patent Term Extensions (PTE), terminal disclaimers, and pre-GATT filing rules. All computation runs in your browser—no data is transmitted.
How U.S. Patent Terms Work
Under 35 U.S.C. § 154, a U.S. utility patent has a term of 20 years measured from the earliest non-provisional filing date. This applies to all patents filed on or after June 8, 1995 (the GATT effective date). For patents filed before that date, the term is the longer of 20 years from filing or 17 years from grant.
The filing date used for term calculation is the earliest non-provisional U.S. filing date. Provisional application filing dates do not count toward the 20-year term, though they establish priority for patentability purposes. Similarly, if the patent claims priority to a foreign application, the foreign filing date does not affect the U.S. patent term.
Patent Term Adjustment (PTA)
Congress enacted PTA provisions (35 U.S.C. § 154(b)) to compensate patent applicants for delays caused by the USPTO during prosecution. The adjustment is calculated as the sum of three categories of delay, minus any applicant-caused delay:
A Delay
Failure to take certain actions within 14 months of filing: issuing first office action, responding to replies, and granting the patent within 4 months of allowance.
B Delay
If the USPTO fails to issue the patent within 3 years of the actual filing date, each day beyond 3 years is added. Time consumed by RCEs, appeals, or interferences is excluded.
C Delay
Delays due to interference proceedings, secrecy orders, or appellate review. These are relatively uncommon.
The total PTA is printed on the front page of the issued patent. Average PTA across all USPTO grants is approximately 300–400 days, though software and biotech patents often see PTAs exceeding 1,000 days due to extended prosecution histories.
Patent Term Extension (PTE)
Under 35 U.S.C. § 156, patents covering products subject to FDA regulatory review may be extended to compensate for the time lost during the approval process. PTE is available for:
- Human drugs (new chemical entities and new formulations)
- Medical devices requiring premarket approval (PMA)
- Food additives and color additives
- Veterinary biological products
The maximum PTE is 5 years, and the total remaining patent term after extension cannot exceed 14 years from the date of FDA approval. Only one patent per product may receive an extension, and the application must be filed within 60 days of approval.
Terminal Disclaimers
A terminal disclaimer is filed to overcome an obviousness-type double patenting rejection. It limits the term of the later-filed patent to expire on the same date as the earlier related patent. This is common in patent families where multiple related applications are filed.
Important implications:
- The disclaimed patent is only enforceable while commonly owned with (or subject to an obligation of common assignment to) the reference patent.
- PTA earned by the later patent is effectively lost if the terminal disclaimer date falls before the PTA-extended expiration.
- Recent USPTO rule changes (2024) added requirements that terminal disclaimers include a provision making the disclaimed patent unenforceable if the reference patent is found invalid.
Maintenance Fees
Even if a patent has remaining term, it will expire prematurely if the holder fails to pay the required maintenance fees. U.S. utility patents require three maintenance fee payments:
| Payment Window | Due Date | Fee (Large Entity, 2026) |
|---|---|---|
| First | 3.5 years after grant | $2,000 |
| Second | 7.5 years after grant | $3,760 |
| Third | 11.5 years after grant | $7,700 |
Small entities pay 50% and micro entities pay 25% of these fees. A 6-month grace period is available with a surcharge. This calculator does not account for unpaid maintenance fees—always verify payment status on USPTO Public PAIR.